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Background: Ambient temperature and humidity are established environmental stressors with regard to influenza infections; however, mapping disease burden is difficult owing to the complexities of the underlying associations and differences in vulnerable population distributions. In this study, we aimed to quantify the burden of influenza attributable to non-optimal ambient temperature and absolute humidity in Japan considering geographical differences in vulnerability., Methods: The exposure-lag-response relationships between influenza incidence, ambient temperature, and absolute humidity in all 47 Japanese prefectures for 2000-2019 were quantified using a distributed lag non-linear model for each prefecture; the estimates from all the prefectures were then pooled using a multivariate mixed-effects meta-regression model to derive nationwide average associations. Association between prefecture-specific indicators and the risk were also examined. Attributable risks were estimated for non-optimal ambient temperature and absolute humidity according to the exposure-lag-response relationships obtained before., Results: A total of 25,596,525 influenza cases were reported during the study period. Cold and dry conditions significantly increased influenza incidence risk. Compared with the minimum incidence weekly mean ambient temperature (29.8 °C) and the minimum incidence weekly mean absolute humidity (20.2 g/m 3 ), the cumulative relative risks (RRs) of influenza in cold (2.5 °C) and dry (3.6 g/m 3 ) conditions were 2.79 (95% confidence interval [CI]: 1.78-4.37) and 3.20 (95% CI: 2.37-4.31), respectively. The higher RRs for cold and dry conditions were associated with geographical and climatic indicators corresponding to the central and northern prefectures; demographic, socioeconomic, and health resources indicators showed no clear trends. Finally, 27.25% (95% empirical CI [eCI]: 5.54-36.35) and 32.35% (95% eCI: 22.39-37.87) of all cases were attributable to non-optimal ambient temperature and absolute humidity (6,976,300 [95% eCI: 1,420,068-9,306,128] and 8,280,981 [95% eCI: 8,280,981-9,693,532] cases), respectively., Conclusions: These findings could help identify the most vulnerable populations in Japan and design adaptation policies to reduce the attributable burden of influenza due to climate variability., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: During invasive mechanical ventilation, where medical gases are very dry and the upper airway is bypassed, appropriate gas conditioning and humidification are mandatory at all times. Results of in vitro studies suggest that dry gases may improve lung deposition during nebulization, but this has not been confirmed through in vivo studies. The objective of this study was to measure gas humidity under multiple conditions to better describe gas hygrometry when heated humidifiers are turned off., Methods: We measured, on a bench, the hygrometry of different gases at steady state: medical gases, at the Y-piece without humidifier, with the humidifier switched off, and with humidifier switched on. We measured gas humidity every 10-60 s during dynamic conditions after switching off the heated humidifier and after switching on the heated humidifier. Hygrometry was measured by using the psychrometric method with at least 3 measurements for each tested condition., Results: We performed 287 psychrometric measurements in different situations. The mean ± SD gas absolute humidity at steady state during different conditions were the following: 1.6 ± 0.2 mg H 2 O/L for the medical gases, 4.5 ± 0.9 mg H 2 O/L at the Y-piece without humidifier, 9.1 ± 0.3 mg H 2 O/L at the Y-piece with heated humidifier turned off, and 34.2 ± 2.2 mg H 2 O/L at the Y-piece with the heated humidifier turned on. During the dynamic evaluation, after turning off the humidifier, humidity was < 30 mg H 2 O/L after a few minutes, attained 15 mg H 2 O/L after 15 min, and was below 10 mg H 2 O/L after 1 h but never reached the level of dry medical gases. After turning on the heated humidifier, the gas hygrometry reached 30 mg H 2 O/L after 5 min., Conclusions: When heated humidifiers are turned off, gas humidity levels are very low but not as low as medical gases. The clinical impact of repeated shutdowns is unknown. As recommended, heated humidifiers should never be turned off during nebulization., Competing Interests: Dr Lellouche’s laboratory has received funding from Fisher & Paykel to develop an educational application (VentilO) and funded several projects of research. Mr Bouchard has disclosed no conflicts of interest., (Copyright © 2024 by Daedalus Enterprises.)

Nasopharyngeal carcinoma (NPC) has a unique geographic distribution. It is unknown whether meteorological factors are related to the incidence of NPC. To investigate the effect of ambient temperature, relative humidity (RH), and absolute humidity (AH) on the incidence of NPC, we collected the incidence rate of NPC in 2016 and meteorological data from 2006 to 2016 from 484 cities and counties across 31 provinces in China. Generalized additive models with quasi-Poisson regression and generalized linear models with natural cubic splines were employed respectively to elucidate the nonlinear relationships and specify the partial linear relationships. Subgroup and interactive analysis were also conducted. Temperature (R 2  = 0.68, p < .001), RH (R 2  = 0.47, p < .001), and AH (R 2  = 0.70, p < .001) exhibited nonlinear correlations with NPC incidence rate. The risk of NPC incidence increased by 20.3% (95% confidence intervals [CI]: [18.9%, 21.7%]) per 1°C increase in temperature, by 6.3% (95% CI: [5.3%, 7.2%]) per 1% increase in RH, and by 32.2% (95% CI: [30.7%, 33.7%]) per 1 g/m 3 increase in AH, between their the 25th and the 99th percentiles. In addition, the combination of low temperature and low RH was also related to increased risk (relative risk: 1.60, 95% CI: [1.18, 2.17]). Males and eastern or rural populations tended to be more vulnerable. In summary, this study suggests that ambient temperature, RH, and particularly AH are associated with the risk of NPC incidence., (© 2024 The Authors. International Journal of Cancer published by John Wiley & Sons Ltd on behalf of UICC.)

Background: For the reason that many studies have been inconclusive on the effect of humidity on respiratory disease, we examined the association between absolute humidity and respiratory disease mortality and quantified the mortality burden due to non-optimal absolute humidity in Guangzhou, China., Methods: Daily respiratory disease mortality including total 42,440 deaths from 1 February 2013 to 31 December 2018 and meteorological data of the same period in Guangzhou City were collected. The distributed lag non-linear model was used to determine the optimal absolute humidity of death and discuss their non-linear lagged effects. Attributable fraction and population attributable mortality were calculated based on the optimal absolute humidity, defined as the minimum mortality absolute humidity., Results: The association between absolute humidity and total respiratory disease mortality showed an M-shaped non-linear curve. In total, 21.57% (95% CI 14.20 ~ 27.75%) of respiratory disease mortality (9154 deaths) was attributable to non-optimum absolute humidity. The attributable fractions due to high absolute humidity were 13.49% (95% CI 9.56 ~ 16.98%), while mortality burden of low absolute humidity were 8.08% (95% CI 0.89 ~ 13.93%), respectively. Extreme dry and moist absolute humidity accounted for total respiratory disease mortality fraction of 0.87% (95% CI - 0.09 ~ 1.58%) and 0.91% (95% CI 0.25 ~ 1.39%), respectively. There was no significant gender and age difference in the burden of attributable risk due to absolute humidity., Conclusions: Our study showed that both high and low absolute humidity are responsible for considerable respiratory disease mortality burden, the component attributed to the high absolute humidity effect is greater. Our results may have important implications for the development of public health measures to reduce respiratory disease mortality., (© 2021. The Author(s).)

This study analyzed the spread and decay durations of the COVID-19 pandemic in different prefectures of Japan. During the pandemic, affordable healthcare was widely available in Japan and the medical system did not suffer a collapse, making accurate comparisons between prefectures possible. For the 16 prefectures included in this study that had daily maximum confirmed cases exceeding ten, the number of daily confirmed cases follow bell-shape or log-normal distribution in most prefectures. A good correlation was observed between the spread and decay durations. However, some exceptions were observed in areas where travelers returned from foreign countries, which were defined as the origins of infection clusters. Excluding these prefectures, the population density was shown to be a major factor, affecting the spread and decay patterns, with R 2 = 0.39 ( p < 0.05), respectively, approximately corresponding to social distancing. The maximum absolute humidity was found to affect the decay duration normalized by the population density ( p < 0.05), respectively, approximately corresponding to social distancing. The maximum absolute humidity was found to affect the decay duration normalized by the population density ( R < 0.05). Our findings indicate that the estimated pandemic spread duration, based on the multivariate analysis of maximum absolute humidity, ambient temperature, and population density (adjusted 2 > 0.36, p < 0.05). Our findings indicate that the estimated pandemic spread duration, based on the multivariate analysis of maximum absolute humidity, ambient temperature, and population density (adjusted R 2 = 0.53, p -value < 0.05), could prove useful for intervention planning during potential future pandemics, including a second COVID-19 outbreak.

Purpose: Recent studies have determined that ambient humidity plays a more important role in aerobic performance than dry-bulb temperature does in warm environments; however, no studies have kept humidity constant and independently manipulated temperature. Therefore, the purpose of this study was to determine the contribution of dry-bulb temperature, when vapor pressure was matched, on the thermoregulatory, perceptual and performance responses to a 30-min cycling work trial., Methods: Fourteen trained male cyclists (age: 32 ± 12 year; height: 178 ± 6 cm; mass: 76 ± 9 kg; [Formula: see text]: 59 ± 9 mL kg -1  min -1 ; body surface area: 1.93 ± 0.12 m 2 ; peak power output: 393 ± 53 W) volunteered, and underwent 1 exercise bout in moderate heat (MOD: 34.9 ± 0.2 °C, 50.1 ± 1.1% relative humidity) and 1 in mild heat (MILD: 29.2 ± 0.2 °C, 69.4 ± 0.9% relative humidity) matched for vapor pressure (2.8 ± 0.1 kPa), with trials counterbalanced., Results: Despite a higher weighted mean skin temperature during MOD (36.3 ± 0.5 vs. 34.5 ± 0.6 °C, p < 0.01), none of rectal temperature (38.0 ± 0.3 vs. 37.9 ± 0.4 °C, p = 0.30), local sweat rate (1.0 ± 0.3 vs. 0.9 ± 0.4 mg cm -2  min -1 , p = 0.28), cutaneous blood flow (283 ± 116 vs. 287 ± 105 PU, p = 0.90), mean power output (206 ± 37 vs. 205 ± 41 W, p = 0.87) or total work completed (371 ± 64 vs. 369 ± 70 kJ, p = 0.77) showed any difference between environments during the work trial. However, all perceptual measures (perceived exertion, thermal discomfort, thermal sensation, skin wettedness, pleasantness, all p < 0.05) were affected detrimentally during MOD compared to MILD., Conclusion: In a warm and compensable environment, dry-bulb temperature did not influence high-intensity cycling performance when vapor pressure was maintained, whilst the perceptual responses were affected.

Background: Climatic factors affect the survival and transmissibility of respiratory viruses causing influenza-like illness (ILI), and we hypothesized that changes in absolute humidity and temperature may affect long-term trends of ILI incidence rate in temperate countries. We tested this hypothesis using ILI and meteorological time series in the Netherlands for the period 1970-2016., Methods: We described the long-term trends of ILI incidence, absolute humidity and temperature; modelled the association between climatic factors and ILI activity using negative binomial regression models; and assessed the strength of the association between the seasonal average absolute humidity (or temperature) and ILI incidence rate using the Spearman's rank correlation coefficient., Results: The ILI incidence rate declined from 1970 and reached a minimum in the season 2002-03, but started to increase again from the season 2003-04 onwards. In the negative binominal regression models, the weekly ILI count was inversely associated (p < 0.001) with 0- and 1-week lagged absolute humidity and temperature. After three decades of rising absolute humidity and temperature (1970-2000), the early 2000s represented a trend-reversal point for the climatic time series. The seasonal average ILI incidence rate and absolute humidity (or temperature) were strongly (inversely) correlated., Conclusions: Our findings suggest that climate change may have played a role in the long-term trends of ILI incidence rates in the Netherlands, as we were able to show that lower humidity and temperature in a given week were associated with higher ILI incidence in the next week, there was a clear time point reversal in climatic parameters and ILI rates in the 2000s, and the average annual ILI incidence was inversely related to average annual temperatures and humidity., (Copyright © 2018. Published by Elsevier Inc.)

Background: During extracorporeal membrane oxygenation for ARDS, a range of 1-4 mL/kg predicted body weight tidal volume (V T ) is commonly used. We explored whether such a low V T could be adequately delivered by ICU ventilators, and whether such low V T s prevent the heated humidifier (HH) from reaching the recommended target of 33 mg/L absolute humidity (AH)., Methods: We attached a lung model to 5 ICU ventilators set in volume controlled mode and body temperature and pressure saturated. We ran 2 protocols over a 100-280 mL V T range used with adult or neonatal breathing circuit at a breathing frequency (f) of 15 (f15) or 30 (f30) breaths/min. In the first protocol, with the HH off, V T was measured with a dedicated data logger and expressed in body temperature and pressure saturated. The relationships of measured V T to set V T were studied, and the relative error in V T was analyzed within its 10% boundaries. In the second protocol, the HH was on, and we measured AH using a psychrometric method. The relationship of AH to set V T was analyzed with linear regression., Results: For the 5 ventilators used, the slope (95% CI) between measured V T versus set V T averaged 0.93 (0.92-0.93), 0.93 (0.93-0.94), 0.91 (0.90-0.91), and 0.91 (0.90-0.91) mL/mL for adult and neonatal circuits at f15 and f30, respectively ( P < .05 vs 1 in each instance), indicating a systematic under-delivery of V T . The V T relative error fell within the ±10% accuracy range for only 2 ventilators with adult circuits at f15 and f30. AH increased linearly with V T . The recommended target of 33 mg/L AH was reached with all of the ventilators for the adult circuit at f30 only. The minimum volume that met the recommended threshold for AH was 100, 150, 190, 160, and 100 mL for the G5, Carestation, PB980, Servo-U, and V500 ventilators, respectively, at f30., Conclusion: Low V T was systematically under-delivered by modern ICU ventilators by roughly 7-9%. To meet the recommended target of 33 mg/L AH, adult circuit at f30 should be used., (Copyright © 2018 by Daedalus Enterprises.)

The emergence of avian influenza A(H7N9) virus poses a pandemic threat to human beings. It was proposed that meteorological factors might be important environmental factors favoring the occurrence of H7N9 infection, but evidence is still inadequate. In this study, we aimed to investigate the independent and interactive effects of ambient temperature (TM) and absolute humidity (AH) on H7N9 infection risks in China. The individual information of all reported H7N9 cases and daily meteorological data in five provinces/municipality (Zhejiang, Jiangsu, Shanghai, Fujian, and Guangdong) in China during 2013-2016 were collected. We employed a case-crossover study design, in which the 7-10days before the onset date of each H7N9 case was defined as the hazard period, and 4weeks before the hazard period was taken as the control period. The average levels of meteorological factors were calculated during the hazard and control periods. A Cox regression model was used to estimate the independent and interactive effects of TM and vapor pressure (VP), an indicator of AH, on H7N9 infection risks. A total of 738 H7N9 cases were included in the present study. Significantly nonlinear negative associations of TM and VP with H7N9 infection risks were observed in all cases, and in cases from northern and southern regions. There were significant interactive effects between TM and VP on H7N9 infection risks, and the risks of H7N9 infection were higher in cold-dry days than other days. We further observed different risky windows of H7N9 infection in the northern (TM: 0-18°C, VP: 313mb) and southern areas (TM: 7-21°C, VP: 3-17mb). We concluded that ambient temperature and absolute humidity had significant independent and interactive effects on H7N9 infection risks in China, and the risks of H7N9 infection were higher in cold-dry days. The risky windows of H7N9 infection were different in the northern and southern areas., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The spatio-temporal distribution of influenza is linked to variations in meteorological factors, like temperature, absolute humidity, or the amount of rainfall. The aim of this study was to analyse the association between influenza activity, and meteorological variables in Spain, across five influenza seasons: 2010-2011 through to 2014-2015 using generalized linear negative binomial mixed models that we calculated the weekly influenza proxies, defined as the weekly influenza-like illness rates, multiplied by the weekly proportion of respiratory specimens that tested positive for influenza. The results showed an association between influenza transmission and dew point and cumulative precipitation. In increase in the dew point temperature of 5 degrees produces a 7% decrease in the Weekly Influenza Proxy (RR 0.928, IC: 0.891-0.966), and while an increase of 10 mm in weekly rainfall equates to a 17% increase in the Weekly Influenza Proxy (RR 1.172, IC: 1.097-1.251). Influenza transmission in Spain is influenced by variations in meteorological variables as temperature, absolute humidity, or the amount of rainfall., Competing Interests: The authors declare no conflict of interest.

Both temperature and humidity may independently or jointly contribute to the risk of human rhinovirus (HRV) infections, either through altered survival and spread of viruses in the environment or due to changes in host susceptibility. This study examined the relationship between short-term variations in temperature and humidity and the risk of HRV infections in a subarctic climate. We conducted a case-crossover study among conscripts (n = 892) seeking medical attention due to respiratory symptoms during their military training and identified 147 HRV cases by real-time PCR. An average temperature, a decline in daily ambient temperature and absolute humidity (AH) during the three preceding days of the onset (hazard period) and two reference periods (a week prior and after the onset) were obtained. The average daily temperature preceding HRV infections was -9.9 ± 4.9 °C and the average AH was 2.2 ± 0.9 g/m³. An average (odds ratios (OR) 1.07 (95% confidence interval (CI) 1.00-1.15)) and maximal (OR 1.08 (1.01-1.17)) change in temperature increased the risk of HRV infections by 8% per 1 °C decrease. An average (OR 1.20 (CI 1.03-1.40)) and maximal decrease (OR 1.13 (CI 0.96-1.34)) in AH increased the risk of HRV infection by 13% and 20% per 0.5 g/m³ decrease. A higher average temperature during the three preceding days was positively associated with HRV infections (OR 1.07 (CI 1.00-1.15)). A decrease rather than low temperature and humidity per se during the preceding few days increases the risk of HRV infections in a cold climate. The information is applicable to populations residing in cold climates for appropriate personal protection and prevention of adverse health effects., Competing Interests: The authors declare no conflict of interest.

Background: High-flow nasal cannula (HFNC) therapy provides better humidification than conventional oxygen therapy. To allay loss of vapor as condensation, a servo-controlled heating wire is incorporated in the inspiratory tube, but condensation is not completely avoidable. We investigated factors that might affect condensation: thermal characteristics of the inspiratory tube, HFNC flow, and ambient temperature., Methods: We evaluated 2 types of HFNC tubes, SLH Flex 22-mm single tube and RT202. Both tubes were connected to a heated humidifier with water reservoir. HFNC flow was set at 20, 40, and 60 L/min, and FIO2 was set at 0.21. Air conditioning was used maintain ambient temperature at close to either 20 or 25°C. We weighed the tubes on a digital scale before (0 h) and at 3, 6, and 24 h after, turning on the heated humidifier, and calculated the amount of condensation by simple subtraction. The amount of distilled water used during 24 h was also recorded., Results: At 25°C, there was little condensation, but at 20°C and HFNC flow of 20, 40, and 60 L/min for 24 h, the amount of condensation with the SLH was 50.2 ± 10.7, 44.3 ± 17.7, and 56.6 ± 13.9 mg, and the amount with the RT202 was 96.0 ± 35.1, 72.8 ± 8.2, and 64.9 ± 0.8 mg. When ambient temperature was set to 20°C, condensation with the RT202 was statistically significantly greater than with the SLH at all flow settings (P < .001)., Conclusions: Ambient temperature statistically significantly influenced the amount of condensation in the tubes., (Copyright © 2016 by Daedalus Enterprises.)

Background: Experimental and ecological studies have shown the role of climatic factors in driving the epidemiology of influenza. In particular, low absolute humidity (AH) has been shown to increase influenza virus transmissibility and has been identified to explain the onset of epidemics in temperate regions. Here, we aim to study the potential climatic drivers of influenza-like illness (ILI) epidemiology in Vietnam, a tropical country characterized by a high diversity of climates. We specifically focus on quantifying and explaining the seasonality of ILI., Methods: We used 18 years (1993-2010) of monthly ILI notifications aggregated by province (52) and monthly climatic variables (minimum, mean, maximum temperatures, absolute and relative humidities, rainfall and hours of sunshine) from 67 weather stations across Vietnam. Seasonalities were quantified from global wavelet spectra, using the value of the power at the period of 1 year as a measure of the intensity of seasonality. The 7 climatic time series were characterized by 534 summary statistics which were entered into a regression tree to identify factors associated with the seasonality of AH. Results were extrapolated to the global scale using simulated climatic times series from the NCEP/NCAR project., Results: The intensity of ILI seasonality in Vietnam is best explained by the intensity of AH seasonality. We find that ILI seasonality is weak in provinces experiencing weak seasonal fluctuations in AH (annual power <17.6), whereas ILI seasonality is strongest in provinces with pronounced AH seasonality (power >17.6). In Vietnam, AH and ILI are positively correlated., Conclusions: Our results identify a role for AH in driving the epidemiology of ILI in a tropical setting. However, in contrast to temperate regions, high rather than low AH is associated with increased ILI activity. Fluctuation in AH may be the climate factor that underlies and unifies the seasonality of ILI in both temperate and tropical regions. Alternatively, the mechanism of action of AH on disease transmission may be different in cold-dry versus hot-humid settings., (Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.)

Influenza viruses cause much winter-time morbidity and death in temperate regions. We still do not understand why 'flu is more common in winter. Since the 1960s, investigators have studied the role of relative humidity and temperature on viral survival, transmission and infection rates but results have demonstrated only inconclusive trends. Over the past few years however, a series of exciting studies have instead focussed on absolute humidity and demonstrated highly significant correlations with viral survival and transmission rates in both laboratory and epidemiological models. Here we review the evidence for a causal association between absolute humidity and 'flu transmission and outline how this could lead to a new approach to curbing this and perhaps other viral epidemics in the winter months., (Copyright © 2015. Published by Elsevier Ltd.)

Background: Because noninvasive ventilation (NIV) delivers medical gas at high flow, inadequate humidification may cause oral dryness and patient discomfort. Heated humidification can be used during NIV, but little has been reported about the effects on the hygrometric conditions inside an oronasal mask and oral dryness during 24 hours on NIV., Methods: We measured absolute humidity (AH) inside oronasal masks on subjects with acute respiratory failure during 24 hours on NIV. A single-limb turbine ventilator and oronasal mask with an exhalation port were used for NIV. Oral moistness was evaluated using an oral moisture-checking device, and 3 times during the 24 hours the subjects subjectively scored the feeling of dryness on a 0-10 scale in which 10 was the most severe dryness., Results: Sixteen subjects were enrolled. The mean ± SD AH inside the mask was 30.0 ± 2.6 mg H2O/L (range 23.1-33.3 mg H2O/L). The median oral moistness was 19.2% (IQR 4.4-24.0%), and the median oral dryness score was 5.5 (IQR 4-7). AH and inspired gas leak correlated inversely, both within the subjects (r = -0.56, P < .001) and between the subjects (r = -0.58, P = .02). AH and oral moistness correlated within the subjects (r = 0.39, P = .04). Oral breathing was associated with reduced oral moistness (P = .001) and increased oral dryness score (P = .002)., Conclusions: AH varied among the subjects, and some complained of oral dryness even with heated humidifier. Oral breathing decreased oral moistness and worsened the feeling of dryness.

Pulse-jet cartridge filters are widely used in industrial dust removal. However, the accumulation of highly sticky dust can cause irreversible blockage of cartridges. This is primarily due to the humidity of the air on the cleaning performance of the filter cartridge. Therefore, this article proposed a new method to solve it by changing the injection air source (nitrogen, compressed air after suction dryer treatment and compressed air after cold dryer treatment), the influence of humidity on system strength and dust residues was assessed. We define absolute humidity above 10 g m−3 as a high humidity condition and vice versa as a low humidity condition. The conclusions are that the injection effect only considers the water content of the injection air source: nitrogen > compressed air after suction dryer treatment > compressed air after cold dryer treatment. In low humidity conditions, the injection air source is the main influence factor, plus the water content of the injection air source, the greater the resistance of the system and the dust residues. In high humidity conditions, the humidity of the air is the most important influence. When the gas-solid concentration and filtration wind speed are constant, the system strength and dust residues increase with the increase in humidity. This study provides new ideas and reliable data sources for the industrial collection of adhesive dust. [ABSTRACT FROM AUTHOR]

Background: At high ambient temperatures in ICU rooms, the humidification performances of heated-wire humidifiers are significantly reduced, with delivered gas humidity well below 30 mg H2O/L, which leads to an increased risk of endotracheal occlusions, subocclusions, or mucociliary dysfunction. The objective of the study was to evaluate the humidity delivered at the Y-piece with new-generation heated-wire humidifiers with advanced algorithm (FP950 [Fisher & Paykel Healthcare, Auckland, New Zealand] and VHB20 [Vincent Medical, Inspired, Hong Kong]) while varying ambient temperatures. Methods: We measured, on the bench, the hygrometry of inspiratory gases delivered by a new generation of heated-wire humidifiers (i) FP950, (ii) VHB20 and a previous generation of heated-wire humidifiers, (iii) MR850 (Fisher & Paykel) with the usual settings (37°C at the chamber/40°C at the Y-piece), (iv) MR850 with no temperature gradient (40°C/40°C), and (v) MR850 with the automatic compensation algorithm activated. Hygrometry was measured with the psychrometric method after 1 h of stability while varying the room temperature from 20 to 30°C. Results: Two hundred ninety-four hygrometric bench measurements were performed at steady state for the different tested conditions. With the new heated-wire humidifiers (FP950 and VHB20), gas humidity delivered remained > 30 mg H2O/L in all tested conditions, even at high ambient temperatures (>25°C). With previous generations of heated-wire humidifiers (MR850), at high ambient temperature, humidity delivered was adequate in only 26% (11/42) of the measurements when the usual settings were used (37°C/40°C) and 30% (11/37) with automatic compensation. When no temperature gradient was set (40°C/40°C), humidity delivered was > 30 mg H2O/L in 91% (30/33) of the measurements at a high ambient temperature. With an ambient temperature < 25°C, almost all devices and settings provided adequate humidity. Conclusions: The new FP950 and VHB20 heated-wire humidifiers by using advanced algorithms demonstrated stable performance while varying the ambient temperature by 20-30°C, better than the previous generation of heated humidifiers when ambient temperatures were high. [ABSTRACT FROM AUTHOR]

To assess the impact of absolute humidity on influenza transmission in Beijing from 2014 to 2019, we estimated the influenza transmissibility via the instantaneous reproduction number (Rt), and evaluated its nonlinear exposure-response association and delayed effects with absolute humidity by using the distributed lag nonlinear model (DLNM). Attributable fraction (AF) of Rt due to absolute humidity was calculated. The result showed a significant M-shaped relationship between Rt and absolute humidity. Compared with the effect of high absolute humidity, the low absolute humidity effect was more immediate with the most significant effect observed at lag 6 days. AFs were relatively high for the group aged 15–24 years, and was the lowest for the group aged 0–4 years with low absolute humidity. Therefore, we concluded that the component attributed to the low absolute humidity effect is greater. Young and middle-aged people are more sensitive to low absolute humidity than children and elderly. [ABSTRACT FROM AUTHOR]

Maintaining a constant drying rate during the drying process is difficult in organic solvents with high evaporation rates. The liquid supply method was adopted in this study to evaluate the drying characteristics during a constant drying rate period. Accordingly, the effect of the absolute humidity of water vapor on the drying characteristics was examined. With an aqueous ethanol solution, the water vapor in the drying gas dissolves in the liquid phase on the material surface, and the gas-liquid equilibrium governs the drying characteristics. With n-hexane, the water vapor in the drying gas condenses on the surface of the drying material. Although water does not dissolve in the liquid phase, it affects the drying characteristics. [ABSTRACT FROM AUTHOR]

This study aimed to quantify the exposure-lag-response relationship between short-term changes in ambient temperature and absolute humidity and the transmission dynamics of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Japan. The prefecture-specific daily time-series of newly confirmed cases, meteorological variables, retail and recreation mobility, and Government Stringency Index were collected for all 47 prefectures of Japan for the study period from 15 February 2020 to 15 October 2022. Generalized conditional Gamma regression models were formulated with distributed lag nonlinear models by adopting the case-time-series design to assess the independent and interactive effects of ambient temperature and absolute humidity on the relative risk (RR) of the time-varying effective reproductive number (Rt). With reference to 17.8 °C, the corresponding cumulative RRs (95% confidence interval) at a mean ambient temperatures of 5.1 °C and 27.9 °C were 1.027 (1.016–1.038) and 0.982 (0.974–0.989), respectively, whereas those at an absolute humidity of 4.2 m/g3 and 20.6 m/g3 were 1.026 (1.017–1.036) and 0.995 (0.985–1.006), respectively, with reference to 10.6 m/g3. Both extremely hot and humid conditions synergistically and slightly reduced the Rt. Our findings provide a better understanding of how meteorological drivers shape the complex heterogeneous dynamics of SARS-CoV-2 in Japan. [ABSTRACT FROM AUTHOR]

With the increasing severity of the malignant tumors situation worldwide, the impacts of climate on them are receiving increasing attention. In this study, for the first time, all-malignant tumors were used as the dependent variable and absolute humidity (AH) was innovatively introduced into the independent variable to investigate the relationship between all-malignant tumors and meteorological factors. A total of 42,188 cases of malignant tumor deaths and meteorological factors in Wuhu City were collected over a 7-year (2014–2020) period. The analysis method combines distributed lagged nonlinear modeling (DLNM) as well as generalized additive modeling (GAM), with prior pre-analysis using structural equation modeling (SEM). The results showed that AH, temperature mean (T mean) and diurnal temperature range (DTR) all increased the malignant tumors mortality risk. Exposure to low and exceedingly low AH increases the malignant tumors mortality risk with maximum RR values of 1.008 (95% CI: 1.001, 1.015, lag 3) and 1.016 (95% CI: 1.001, 1.032, lag 1), respectively. In addition, low and exceedingly low T mean exposures also increased the risk of malignant tumors mortality, the maximum RR was 1.020 (95% CI: 1.006, 1.034) for low T mean and 1.035 (95% CI: 1.014, 1.058) for exceedingly low T mean. As for DTR, all four levels (exceedingly low, low, high, exceedingly high, from low to high) of exposure increased the risk of death from malignant tumors, from exceedingly low to exceedingly high maximum RR values of 1.018 (95% CI: 1.004, 1.032), 1.011 (95% CI: 1.005, 1.017), 1.006 (95% CI: 1.001, 1.012) and 1.019 (95% CI: 1.007, 1.031), respectively. The results of the stratified analysis suggested that female appear to be more sensitive to humidity, while male require additional attention to reduce exposure to high level of DTR. [ABSTRACT FROM AUTHOR]

New Findings: What is the central question of this study?What are the independent effects of air temperature and humidity on performance, physiological and perceptual responses during endurance exercise?What is the main finding and its importance?When examined independently, elevated air temperature increased heat strain and impaired aerobic exercise performance, but to a lesser extent than has been reported previously. These findings highlight the importance of absolute humidity relative to temperature when exercising or working under severe heat stress. Many studies have reported that ambient heat stress increases physiological and perceptual strain and impairs endurance exercise, but effects of air temperature per se remain almost unexamined. Most studies have used matched relative humidity, thereby exponentially increasing absolute humidity (water content in air) concurrently with temperature. Absolute (not relative) humidity governs evaporative rate and is more important at higher work rates and air temperatures. Therefore, we examined the independent effects of air temperature and humidity on performance, thermal, cardiovascular and perceptual measures during endurance exercise. Utilizing a crossover design, 14 trained participants (7 females) completed 45 min fixed‐intensity cycling (70% V̇O2peak${\dot V_{{{\rm{O}}_{\rm{2}}}{\rm{peak}}}}$) followed by a 20‐km time trial in each of four environments: three air temperatures at matched absolute humidity (Cool, 18°C; Moderate, 27°C; and Hot, 36°C; at 1.96 kPa, air velocity ∼4.5 m/s), and one at elevated humidity (Hot Humid, 36°C at 3.92 kPa). Warmer air caused warmer skin (0.5°C/°C; P < 0.001), higher heart rate (1 bpm/°C; P < 0.001), sweat rate (0.04 l/h/°C; P < 0.001) and thermal perceptions during fixed‐intensity exercise, but minimally affected core temperature (<0.01°C/°C; P = 0.053). Time‐trial performance was comparable between Cool and Moderate (95% CI: –1.4, 5.9%; P = 0.263), but 3.6–6% slower in Hot (95% CI: ±2.4%; P ≤ 0.006). Elevated humidity increased core temperature (P < 0.001), perceived temperature and discomfort but not skin temperature or heart rate, and reduced mean blood pressure (P = 0.046) during fixed‐intensity exercise. Elevated humidity impaired time‐trial performance by 3.4% (95% CI: ±2.2%; P = 0.006). In conclusion, these findings quantify the importance of absolute humidity alongside air temperature when exercising under severe heat stress. [ABSTRACT FROM AUTHOR]

As the climate continues to change, suicide is becoming more frequent. In this study, absolute humidity (AH) was included for the first time and Wuhu, a typical subtropical city along the Yangtze River, was taken as the research object to explore the impact of suicide death risk on meteorological factors. The daily meteorological factors and suicide mortality data of Wuhu city from 2014 to 2020 were collected. Guided by structural equation model (SEM), a time series analysis method combining distributed lag nonlinear model (DLNM) and generalized additive model (GAM) was adopted. To investigate the correlation among different populations, we stratified age and gender at different meteorological levels. A total of 1259 suicide deaths were collected in Wuhu. The results indicated that exceedingly low and low levels of AH short-term exposure increased suicide mortality, with the maximum effect occurring at lag 14 for both levels of exposure, when the relative risk (RR) was 1.131 (95% CI: 1.030, 1.242) and 1.065 (95% CI: 1.006, 1.127), respectively. Exposure to exceedingly high and exceedingly low levels of temperature mean (T mean) also increased suicide mortality, with maximum RR values of 1.132 (lag 14, 95% CI: 1.015, 1.263) and 1.203 (lag 0, 95% CI: 1.079, 1.340), sequentially. As for diurnal temperature range (DTR), low-level exposure decreased the risk of suicide, while high-level exposure increased this risk, with RR values of 0.955 (lag 0, 95% CI: 0.920, 0.991, minimum) and 1.060 (lag 0, 95% CI: 1.018, 1.104, maximum), sequentially. Stratified analysis showed that AH and DTR increased the suicide death risk in male and elderly people, while the risk effect of T mean have no effect on young people only. In summary, male and elderly people appear to be more vulnerable to adverse weather effects. [ABSTRACT FROM AUTHOR]

Animals breeding in nest‐boxes experience nesting environments in which they did not originally evolve. Despite the central importance of nesting microclimate for offspring fitness, little is known about the thermal properties of human‐provided nest sites compared to natural ones. In particular, comparisons with offspring in the nest are lacking. Here, we compare microclimate (temperature and absolute humidity) from the onset of breeding, thus starting with nest‐site choice and ending with the post‐fledging stage, quantified in natural cavities and nest‐boxes used by several species of hollow‐nesting birds in a temperate deciduous forest. We confirm that across all nesting stages, nest‐boxes were thermally unstable when compared to natural cavities, with higher temperature maximums, larger amplitudes and worse insulation from maximum ambient temperatures relative to natural cavities. Surprisingly, as average humidity of natural cavities was previously shown to be higher than in nest‐boxes, in the presence of actively thermoregulating young, nest‐boxes were more humid than natural cavities. When offspring were in the nest, internal microclimatic shifts were mitigated three times more effectively in natural cavities than in nest‐boxes (in terms of mean daily differences from ambient temperature). Artificial cavity microclimate is likely to amplify the adverse effects of projected temperature increases by compromising thermoregulation of developing animals. We stress that conservation efforts should focus on the protection of areas offering natural breeding‐hollows to reduce the potential impacts of climate change on breeding animals. [ABSTRACT FROM AUTHOR]

BACKGROUND: Under-humidification and associated complications may occur with heated humidifiers. Hygrometric performances of heated wire humidifiers are reduced by high ambient and high outlet ventilator temperatures. Currently, there is no reliable monitoring tool to evaluate humidification performances of heated wire humidifiers in the daily practice. We sought to demonstrate the relation between humidity delivered by heated wire humidifiers and different parameters that could be used to monitor humidity of gas delivered to subjects. METHODS: On a bench test, we measured heater plate temperature, inlet chamber temperature, and delivered humidity with MR850 system. Temperature displayed on the humidifier was also recorded. The measurements were performed at different ambient temperatures and five minute ventilation levels (5, 7.5, 10, 12.5, 15 L/min). Inlet chamber temperatures varied from 20-40° C. In each condition, hygrometric measurements with the psychrometric method were performed at steady state. RESULTS: We performed 279 measurements at steady state including all conditions. We found a good correlation between heater plate temperature and absolute humidity delivered (R² = 0.82). This relationship was hardly affected by ambient temperature, but minute ventilation had more effect. For different minute ventilations, the correlation between heater plate temperature and absolute humidity delivered was very good with coefficient of determination R² from 0.87-0.98. Heater plate temperature > 62° C was a good predictor of absolute humidity delivered > 30 mg H2O/L (area under the curve = 0.96, sensibility 79%, specificity 94%). No correlation existed between humidity delivered and the outlet chamber temperature (displayed on the humidifier). CONCLUSIONS: In this bench study, we have shown a good correlation between heater plate temperature and humidity delivered with a heated wire humidifier. This means that a "hidden" hygrometer is built into the heated wire humidifier. Heater plate temperature should be used as a surrogate of humidity to improve the humidification monitoring. [ABSTRACT FROM AUTHOR]

Until now, we have no thorough understanding the role of absolute humidity on influenza activity, especially in tropical and subtropical areas. In this study, we investigated the relationship between absolute humidity and influenza activity in seven municipalities/provinces covering different climatic zones in China. Weekly meteorological data and influenza surveillance data in seven provinces/municipalities in China were collected from January 2012 to December 2019. A distributed lag nonlinear model was adopted to investigate the association between absolute humidity (AH) and influenza activity in each study site. Then, seven study sites were grouped into three regions: northern, intermediate, and southernmost regions. A multivariate meta-analysis was applied to estimate the exposure-lag-response associations in three regions. The province-specific or municipality-specific curves appeared to be nonlinear, and the association between influenza activity and AH varied across regions. In Beijing and Tianjin, located in northern China, the cumulative relative risks (RRs) increased as weekly average AHmean fell below 3.41 g/m3 and 6.62 g/m3. In Guangdong and Hainan, located in southernmost China, the risk of influenza activity increased with rising average AHmean with 16.74 g/m3 and 20.18 g/m3 as the break points. In Shanghai, Zhejiang, and Chongqing, the relationship between weekly average AHmean and influenza could be described as U-shaped curves, with the lowest RRs when weekly average AHmean was 11.95 g/m3, 11.94 g/m3, and 15.96 g/m3, respectively. Meta-analysis results showed the cumulative RRs significantly increased as weekly average AHmean fell below 3.86 g/m3 in the northern region, whereas significantly increased as weekly average AHmean rose above 18.46 g/m3 and 15.22 g/m3 in intermediate and southernmost regions, respectively. Both low and high AH might increase influenza risk in China, and the relationship varies geographically. Our findings suggest that public health policies for climate change adaptation should be tailored to the local climate conditions. [ABSTRACT FROM AUTHOR]

BACKGROUND: High-flow nasal cannula (HFNC) is increasingly used for the management of respiratory failure. Settings include FIO2, total gas flow, and temperature target. Resulting absolute humidity (AH) at the nasal cannula may affect clinical tolerance, and optimal settings with respect to hygrometry remain poorly documented. METHODS: A bench study was designed to assess AH delivered by 4 HFNC devices (Optiflow, Airvo 2, Precision Flow, and Hydrate) according to flow, ambient temperature, and other available settings. Clinical tolerance of different levels of hygrometry (20, 30, and 40 mg H2O/L) was evaluated in 15 healthy volunteers. RESULTS: With FIO2 set at 1.0, normal ambient temperature, and settings made accordingly to the manufacturers' recommendations, mean ± SD AH was 42.2 ± 3.1, 39.5 ± 1.8, 35.7 ± 2.0, and 32.9 ± 2.7 mg H2O/L for the Airvo 2, Optiflow, Hydrate, and Precision Flow, respectively, (P < .001). AH dropped from -3.5 to -10.7 mg H2O/L (P <. 001) with high ambient temperature, except for the Precision Flow. Increasing flow did not significantly affect AH except for the Precision Flow (from 36.4 ± 1.6 to 29.8 ± 0.2 mg H2O/L at 10 and 40 L/min, respectively, [P < .001]). The lowest AH was encountered with the Optiflow set with noninvasive ventilation (NIV) mode, without compensation algorithm, and at high ambient temperature (14.2 ± 1.5 mg H2O/L). In studied subjects, AH significantly affected breathing comfort, reduced from 7.0 ± 1.0 to 3.0 ± 2.0 at 40 and 20 mg H2O/L, respectively, (P < .001). Comfort was similar at 30 and 40 mg H2O/L. CONCLUSIONS: When used according to manufacturer's recommendations and at normal ambient temperature, all the HFNC devices evaluated achieved satisfactory hygrometric output with respect to breathing comfort evaluated in healthy subjects (≥ 30 mg H2O/L). Substantial differences exist between devices, and optimal knowledge of their working principles is required as inappropriate usage may dramatically alter efficacy and clinical tolerance. [ABSTRACT FROM AUTHOR]

The Brazilian Cerrado is a global biodiversity hotspot with notoriously high rates of native vegetation suppression and wildfires over the past three decades. As a result, climate change can already be detected at both local and regional scales. In this study, we used three different approaches based on independent datasets to investigate possible changes in the daytime and nighttime temperature and air humidity between the peak of the dry season and the beginning of the rainy season in the Brazilian Cerrado. Additionally, we evaluated the tendency of dew point depression, considering it as a proxy to assess impacts on biodiversity. Monthly increases of 2.2−4.0℃ in the maximum temperatures and 2.4−2.8℃ in the minimum temperatures between 1961 and 2019 were recorded, supported by all analyzed datasets which included direct observations, remote sensing, and modeling data. The warming raised the vapor pressure deficit, and although we recorded an upward trend in absolute humidity, relative humidity has reduced by ~15%. If these tendencies are maintained, gradual air warming will make nightly cooling insufficient to reach the dew point in the early hours of the night. Therefore, it will progressively reduce both the amount and duration of nocturnal dewfall, which is the main source of water for numerous plants and animal species of the Brazilian Cerrado during the dry season. Through several examples, we hypothesize that these climate changes can have a high impact on biodiversity and potentially cause ecosystems to collapse. We emphasize that the effects of temperature and humidity on Cerrado ecosystems cannot be neglected and should be further explored from a land use perspective. [ABSTRACT FROM AUTHOR]

As a basis for the electrical tomography of laboratory-scale rock samples (~ 10 cm), we developed a procedure for stable, multi-point, electrical measurement on rock samples that is effective even at high contact and sample resistance. Electrodes were strongly attached to the surface of high-resistivity rock using conductive and adhesive epoxy. Sustained current injection for long periods into high-resistance rocks was fulfilled using a constant direct current source with high internal resistance. Accurate voltage measurement across the high-resistance rock was accomplished by differential measurement using two high input resistance voltmeters. Measurements of high resistance also require a stable measurement environment: the temperature and humidity in the laboratory were controlled using an air conditioner, a humidifier, a dehumidifier, and a vinyl tent. Signal noise arising from human activities was eliminated by the remote operation of the measuring equipment and switching terminal. The proposed measurement procedure was evaluated in terms of the stability and accuracy of measured values and its applicability to electrical tomography. To assess measurement stability, we performed multiple measurements of a dry granite sample at various levels of absolute humidity. Our procedure recorded highly reproducible measurements under each humidity condition. The observed changes in measured values with absolute humidity indicate the importance of stabilising the temperature and humidity conditions in the laboratory. Applying our technique to multiple plastic samples with known resistivity confirmed its accuracy. To evaluate its applicability to electrical tomography, we measured the potential distribution on a dry granite surface in response to an injected current using a simple 40-electrode array. The potential distribution measured by our procedure agreed well with that predicted by forward modelling, demonstrating the robustness of our procedure in array measurements, and thus indicating its potential applicability to tomographic measurements for a variety of targets even under severe conditions including the relative dryness of ambient humidity. [ABSTRACT FROM AUTHOR]

Background: The human skin is greatly affected by external factors such as UV radiation (UVR), ambient temperature (T), and air humidity. These factors oscillate during the year giving rise to the seasonal variations in the skin properties. The aim of this study was to evaluate the effect of seasons, environmental T, relative and absolute humidity on the skin parameters of Caucasian women, perform a literature review and discuss the possible factors lying behind the found changes. Materials and Methods: We measured stratum corneum (SC) hydration, transepidermal water loss (TEWL), sebum level, erythema index, and elasticity parameters R2 and R7 on the forehead and the cheek of Caucasian women from the Czech Republic throughout the year. We also performed a non‐systematic literature review focused on the seasonal variations in these skin parameters. Results: We confirmed a well‐documented low SC hydration and sebum production in winter. In spring, we found the lowest TEWL (on the forehead) and the highest SC hydration but also the highest erythema index and the lowest elasticity presumably indicating skin photodamage. For most of the skin parameters, the seasonal variations probably arise due to a complex action of different factors as we extensively discussed. Conclusion: The data about the seasonal variations in the skin parameters are still highly inconsistent and further studies are needed for better understanding of the normal skin changes throughout the year. [ABSTRACT FROM AUTHOR]

The variations of the concentration and characteristics of particulate matter (PM) are influenced by several factors, such as emission sources and meteorological conditions. In this study, fine particles (PM2.5) and ultrafine particles (PM0.1) were simultaneously collected during summer and winter in Hanoi, Vietnam, to clarify the behavior of PM0.1 (which is rarely observed in this region) by characterizing the chemical components of each particle size in order to clarify particle formation and growth in two seasons with different humidity. The results showed that organic carbon (OC) and elemental carbon (EC) were the major compounds in both size ranges of PM, accounting for up to 56% and 80% of the analyzed components in PM2.5 and PM0.1, respectively. Secondary organic carbon (SOC) accounted for 36–41% and 37–47% of the total OC in PM2.5 and PM0.1, respectively, indicating an important contribution of secondary sources to OC. The strong correlations between water-soluble organic carbon (WSOC) and both sulfate (SO42−) and nitrate (NO3−) showed that photochemical reactions contributed considerably to WSOC formation. Furthermore, the correlations between absolute humidity and other chemical components suggest that the PM2.5 collected in Hanoi was formed by secondary processes in the aqueous phase on the aerosol surface. In contrast, no correlation was found between the relative humidity and other chemical components. These observations indicate that particle growth is dependent on the number of water molecules above a certain level under drizzle-like weather conditions particular to the study region, whereas occasional heavy rain during the sampling period might have hindered those processes. [ABSTRACT FROM AUTHOR]

• The relation of relative humidity and temperature can be expressed as: Q = A 1 - A 2 1 + e d x ζ (a + A e - t b ) + A 2. • The charge-to-mass ratio of sulfur decreased with increases in absolute humidity. • Humidify sulfur better eliminate static electricity than raising absolute humidity. The accumulation of static electricity is a big headache in the industry of sulfur ultrafine pulverization, as the fluidized sulfur powder charged with electricity will change the flow behavior, causing particles aggregation and lowered pulverization efficiency, which will impede the pneumatic transmission and collection system or even trigger the fire blast. In order to effectively reduce the accumulation of static electricity in the dry pulverization process of sulfur, LNI-330A impact mill was utilized to prepare −200-mesh sulfur powder, aiming to explore the influence of absolute humidity and wet basis moisture content on charge-to-mass ratio of the sulfur powder. The results show that the charge-to-mass ratio of sulfur powder decreased with the increase of the absolute humidity, and the formula implying the relation of the charge-to-mass ratio with relative humidity and the temperature was converted: Q = A 1 - A 2 1 + e d x ζ (a + A e - t b ) + A 2. Increased wet basis moisture content could also lower the charge-to-mass ratio, e.g. raising the wet basis moisture content of sulfur powder from 0 to 1.469% could lower the charge-to-mass ratio by 80.91%, and direct humidification of sulfur could better lower the charge-to-mass ratio of sulfur powder than increasing absolute humidity. This study provides a feasible method for reducing of static electricity in the process of the ultrafine pulverization to promote safety and pollution reduction in chemical engineering production. [ABSTRACT FROM AUTHOR]

The impact of grass fires on environment and grass ecosystems is mainly negative. The fire hazard of herbaceous plants causes the occurrence and spread of fires in herbaceous ecosystems. Various indicators, in particular the humidity of the combustible material, the selfignition temperature, etc., can estimate it. These indicators depend on the type of plants and the natural conditions that determine the properties of the combustible materials. The goal of the research is to determine the fire hazard indicators of five the most widespread herbaceous plants in Ukrainian ecosystems (Festuca arundinacea, Festuca pratensis, Elymus repens, Phleum pretense and Trifolium arvense) and to substantiate these indicators due to results of thermogravimetric analysis and values of absolute humidity and self-ignition temperature. Within 5 days, the absolute humidity of the samples as well as the self-ignition temperature were determined by weight method and using the OTP testing device. Complex thermal analysis of samples was also perform using a Q-1500D derivatograph. The results of the research show that absolute humidity and selfignition temperature of certain types of plants specify differences in their fire-fighting properties. According to the results of complex thermal analysis for each plant species, three stages occur at different temperatures: evaporation of free and bound water, self-ignition of samples and combustion of carbonized residue. The maximum exothermic effect for each plant was characterized by different value of temperature, as well as ash residue, which impedes the combustion process. [ABSTRACT FROM AUTHOR]

This paper presents the results of identifying the transient response of a relative air humidity sensor. It is shown that the capacitive relative humidity sensor is an integrated microprocessor system that performs joint processing of the readings of the absolute humidity sensor and the temperature sensor. A mathematical model of the relative humidity measurement process is proposed. The transient responses of the absolute humidity sensing element and the temperature sensor are specified under the assumption that they correspond to first-order aperiodic factors. Based on the relationships of thermodynamics, Arden Buck equation, and given transient functions, analytical dependencies are obtained to identify the parameters of the transient response of the capacitive relative humidity sensor. The results of several field experiments are processed and analyzed in accordance with the proposed mathematical model. The effect of anomalous sensor readings is revealed and consists in the fact that with simultaneous stepwise changes in humidity and temperature, the sensor records a change in relative humidity with the opposite sign. It has been established that the cause of the anomalous results of relative humidity measurements is the presence of a large difference between the response time constant of the absolute humidity sensing element and that of the temperature sensor. Measures are proposed to prevent anomalous results of relative humidity measurements. [ABSTRACT FROM AUTHOR]

The vertical distribution of vegetation types along an elevational gradient in mountain areas largely depends on the elevational changes in air temperature and humidity. In this study, we presented the seasonal and diurnal variations in the elevational gradients of air temperature and humidity on the southern and northern slopes in the middle Tianshan Mountain Range using data collected throughout the year via HOBO data loggers. The measurements were conducted at 12 different elevations from 1548 to 3277 m from September 2004 to August 2005. The results showed that the annual mean air temperature decreased along the elevational gradients with temperature lapse rates of (0.71±0.20)°C/100 m and (0.59±0.05)°C/100 m on the northern and southern slopes, respectively. The annual mean absolute humidity significantly decreased with increasing elevation on the northern slope but showed no significant trend on the southern slope. The annual mean relative humidity did not show a significant trend on the northern slope but increased with increasing elevation on the southern slope. The mean air temperature lapse rate exhibited significant seasonal variation, which is steeper in summer and shallower in winter, and this value varied between 0.37°C/100 m and 0.75°C/100 m on the southern slope and between 0.30°C/100 m and 1.02°C/100 m on the northern slope. The mean absolute and relative humidity also exhibited significant seasonal variations on both slopes, with the maximum occurring in summer and the minimum occurring in winter or spring. The monthly diurnal range of air temperature on both slopes was higher in spring than in winter. The annual range of air temperature on the southern slope was higher than that on the northern slope. Our results suggest that significant spatiotemporal variations in humidity and temperature lapse rate are useful when analyzing the relationships between species range sizes and climate in mountain areas. [ABSTRACT FROM AUTHOR]

Rock resistivity measurements under non-wet conditions are essential for interpreting subsurface shallow resistivity structure. This study investigated the resistivity of rock samples collected from several locations around the Nakadake craters of Aso Volcano, Japan. The resistivity of rock samples exhibited a logarithmically linear relationship with changes in absolute humidity, corresponding to possible seasonal variations and correlating with the porosity of rocks. As the samples maintained an identical cylindrical shape and size, the observed variations in humidity were unrelated to the external surface area but were caused by the internal pore structure of rocks. Furthermore, the external surface area of homogeneous granite was artificially varied using slits and its measured resistivity did not vary in the presence of slits. The measured distribution of electrical potential was well explained by a homogeneous model, and less so by a two-layer model, indicating that the region of resistivity change was not restricted to the surface of the sample, but rather covered the entire sample. Further, changes in resistivity in response to absolute humidity were caused by the adsorption of water molecules onto minerals at internal pore surfaces, as evidenced by the measured temporal scale of resistivity change based on a simple concentration–diffusion process of gaseous water molecules caused by humidity changes in the external environment. These findings imply significant variations in the resistivity of shallow subsurfaces owing to humidity changes; thus, the consideration of humidity is important for the interpretation of subsurface shallow resistivity structures. • Resistivity of granite and Aso volcanic rock under non-wet conditions were measured. • Resistivity showed a logarithmically linear relationship with humidity changes. • Changes in resistivity caused by the adsorption of water molecules onto minerals. • Humidity fluctuations can cause variations in the resistivity of shallow subsurfaces. • Humidity should be considered for understandings of subsurface shallow structures. [ABSTRACT FROM AUTHOR]

Abstract A pulse-jet bag filter, representative of those implemented in waste incineration plants for flue gas treatment, was studied at laboratory scale to evaluate the influence of air humidity on the filtration performance. Several cycles of clogging/unclogging were performed with non-hygroscopic submicronic particles with a nanosized fraction with on-line cleaning at operating conditions as similar as possible to those found in the flue gas treatment of waste incineration plants (150 °C – 73 g/m3 of absolute humidity), and in dry conditions (150 °C). The results revealed a significant influence of air humidity on the bag filter performance: faster increase of bag filter pressure drop during clogging in presence of humidity due to water capillary condensation, lower efficiency of particulate cake unclogging and better collection efficiency of particles between 110 and 300 nm in diameter. Highlights • Air humidity significantly affects the particulate cake resistance to airflow. • Capillary condensation is the main reason to the formation of compact dust cake. • Cleaning system is less efficient in the presence of significant air humidity. • Collection efficiency increases with humidity for particle sizes higher than 110 nm. [ABSTRACT FROM AUTHOR]

The occurrence of influenza in different climates is shown to be associated with multiple meteorological factors. Incidence of influenza has been reported to increase during rainy seasons in tropical climates and during dry, cold months of winter in temperate climates. This study was designed to explore the role of absolute humidity (AH), relative humidity (RH), temperature, and wind speed (WS) on influenza activity in Toronto area, Ontario, Canada. Environmental data obtained from four meteorological stations in Toronto area, for the period of January 1, 2010 to December 31, 2015, were linked to patient's influenza data obtained for the same locality and period. Data were analyzed using correlation, negative binomial regressions with linear predictors and splines to capture the non-linear relationship between exposure and outcomes. Our study found a negative association of both AH and temperature with influenza A and B viruses. Effect of RH in influenza A and B was controversial Temperature fluctuation was associated with increased influenza B virus. Influenza virus was less likely to be detected from community patients than those tested as part of an institutional outbreak investigation. This could be more indicative of nosocomial transmission, rather than climactic factors. The non-linear nature of the relation between influenza A virus and temperature and influenza B virus and AH, RH and temperature could explain the complexity and variation between influenza A and B viruses. Predicting influenza activity is important for the timing of disease prevention and control measures as well as for resource allocation. [ABSTRACT FROM AUTHOR]

• Switching impulse discharge experiments of rod-plane air gaps with different front times and absolute humidity are carried out. • Corrected U 50% of different front times when considering atmospheric parameters and absolute humidity. • Analyzed the main influencing factors of air gap discharge time under different conditions. In long-distance transmission lines, the switching overvoltage waveform differs from that of ordinary lines. The wave front time is primarily distributed above 1000 μs. And the switching overvoltage waveform has an important influence on the design of external insulation. This paper aims to deeply study the effect of various factors on the discharge of air gaps under the long front switching impulse voltage. This paper selects three kinds of rod-plane air gaps, and the switching impulse discharge experiments with different front lengths and absolute humidity under positive polarity are carried out. The effects of front time T f , absolute humidity h , and gap distance d on the discharge characteristics of the air gap are analyzed. The results show that the U 50% of an air gap is positively correlated with absolute humidity, front time, and gap distance. When considering the additional influence of humidity, the humidity additional influence factor c and the atmospheric parameter influence index n at different front times are almost unchanged. With the increase in gap distance, the influence of front time on U 50% is more obvious. With the growth of the operating wave front time, the rising rate of U 50% tends to slow down. The discharge time of the air gap under different conditions is mainly determined by the front time. The research results can provide a theoretical and experimental reference for the influence of front time T f and atmospheric parameters on the discharge characteristics of air gaps under long front switching impulse. [ABSTRACT FROM AUTHOR]

Range performance of a thermal imaging system is characterised by the prevailing atmospheric condition present at that time. There are two dominant parameters that limit the range performance of any thermal imaging systems i.e. ambient temperature and relative humidity. In the present work, comparative study of acquisition range performance of thermal imaging system operating in the long wavelength infrared (LWIR) and medium wavelength infrared (MWIR) and spectral bands has been presented as a function of absolute humidity (AH) which is responsible for attenuation of IR radiation due to water vapour molecules present in path length. Presentation of acquisition range as function of AH leads to a single range performance table/graph for thermal imaging system under consideration for predefined visibility, target size, ambient temperature, target to background temperature difference and relative humidity. This table/graph can be used to predict detection, recognition and identification ranges for any set of combination of air temperature and relative humidity. The approach presented in this paper is versatile and has been illustrated through comparative performance analysis of LWIR and MWIR thermal imaging systems based on 640 x 512 staring focal plane array having identical design parameters in terms of resolution. It has been shown that MWIR performance is superior to LWIR beyond a crossover value of AH(T) even though MRTD of MWIR sensor is inferior to that of LWIR sensor at all spatial frequencies. Study has been carried out both for clear atmosphere and hazy conditions. [ABSTRACT FROM AUTHOR]

This study was to evaluate the effect of absolute humidity ( AH), a combined factor of temperature and relative humidity ( RH), on inactivation of avian influenza viruses ( AIVs) on surfaces. Suspensions of the H9N2 or H6N2 AIV were deposited onto carrier surfaces that were either porous (pine wood) or non-porous (stainless steel, synthetic rubber and glass). The inoculated carriers were incubated at 23, 35 or 45°C with 25% or 55% RH for up to 28 days. After incubation, virus was recovered and quantified by chicken embryo assays. The time required to obtain a log10 reduction in virus infectivity (D-value) was estimated using a linear regression model. At AH of 5.2 g/m3 (23°C & 25% RH), both viruses survived up to 14 days on the porous surface and for at least 28 days on the non-porous surfaces. The corresponding D-values for H9N2 and H6N2 were 1.49 and 6.90 days on the porous surface and 7.81 and 12.5 days on the non-porous surfaces, respectively. In comparison, at AH of 9.9 g/m3 (35°C & 25% RH) or 11.3 g/m3 (23°C & 55% RH), the D-values for H9N2 and H6N2 dropped to ≤0.76 day on the porous surface and to ≤1.81 days on the non-porous surfaces. As the AH continued to rise from 11.3 to 36.0 g/m3, the D-value for both viruses decreased further. The relationship between D-value and AH followed a form of y = ax− b for both viruses. The D-values for H9N2 virus were significantly lower ( P < 0.05) than those for H6N2 virus. Exposure to ammonia gas at concentrations of 86 and 173 ppm did not significantly alter test results. The findings give evidence that increasing the AH in poultry buildings following an outbreak of disease could greatly reduce the length of time required for their decontamination. [ABSTRACT FROM AUTHOR]

An expression is obtained for the energy band bending eφ on the surface of the SnO film in the clean air + hydrogen mixture. It is assumed that the value of eφ depends not only on the surface charge density of adsorbed oxygen ions O, but also on the negative charged hydroxyl groups (OH). The results of the analysis of the dependences of eφ on the hydrogen concentration $$ {\mathrm{n}}_{{\mathrm{H}}_2} $$ and the absolute humidity of the gas mixture obtained during the operation of the sensor in the thermo-cyclic mode are presented. A method for the determining $$ {\mathrm{n}}_{{\mathrm{H}}_2} $$ in the examined gas mixture is proposed. The method based on the dependence of eφ on the hydrogen concentration established during the calibration of the sensor is proposed. The dependences of the energy band bending on the SnO surface at $$ {\mathrm{n}}_{{\mathrm{H}}_2} $$ = 0 and the conductivity of the sensor on its temperature during the heating period are discussed. [ABSTRACT FROM AUTHOR]

BACKGROUND: High-flow nasal cannula (HFNC) therapy provides better humidification than conventional oxygen therapy. To allay loss of vapor as condensation, a servo-controlled heating wire is incorporated in the inspiratory tube, but condensation is not completely avoidable. We investigated factors that might affect condensation: thermal characteristics of the inspiratory tube, HFNC flow, and ambient temperature. METHODS: We evaluated 2 types of HFNC tubes, SLH Flex 22-mm single tube and RT202. Both tubes were connected to a heated humidifier with water reservoir. HFNC flow was set at 20, 40, and 60 L/min, and F... was set at 0.21. Air conditioning was used maintain ambient temperature at close to either 20 or 25°C. We weighed the tubes on a digital scale before (0 h) and at 3, 6, and 24 h after, turning on the heated humidifier, and calculated the amount of condensation by simple subtraction. The amount of distilled water used during 24 h was also recorded. RESULTS: At 25°C, there was little condensation, but at 20°C and HFNC flow of 20, 40, and 60 L/min for 24 h, the amount of condensation with the SLH was 50.2 ± 10.7, 44.3 ± 17.7, and 56.6 ± 13.9 mg, and the amount with the RT202 was 96.0 ± 35.1, 72.8 ± 8.2, and 64.9 ± 0.8 mg. When ambient temperature was set to 20°C, condensation with the RT202 was statistically significantly greater than with the SLH at all flow settings (P < .001). CONCLUSIONS: Ambient temperature statistically significantly influenced the amount of condensation in the tubes. [ABSTRACT FROM AUTHOR]