Search

Satisfying indoor air quality in public environments has become essential in cities. In the present study, indoor PM2.5, CO2, NO2, SO2, nicotine, and BTEX have been assessed in 12 categories of public places. The highest average concentrations of PM2.5, NO2, and SO2 were observed in waterpipe cafés (233, 29.6, and 5.1 µg/m3), whereas the lowest concentrations were found in health clubs and hospitals, respectively. Moreover, indoor BTEX concentration varied from 69.5 µg/m3 (passenger terminals) to 1739.2 µg/m3 (elderly care centers). Given nicotine, the highest concentrations were found in waterpipe cafés, ranging from approximately 11.0 to 50 µg/m3. The mean hazard quotient (HQ) and Hazard Index (HI) for benzene, toluene, ethylbenzene, and xylene were calculated in all types of public environments, and results showed that the amount of HQ and HI in none of the places was more than 1. Furthermore, the lifetime cancer risk (LTCR) exceeded the guideline threshold in hospitals, restaurants, elderly care centers, passenger terminals, movie theaters, and beauty salons. The findings of our study indicate that the indoor air quality in most public settings within Tehran city is not acceptable and necessitates appropriate management. These findings underscore the importance of monitoring indoor air quality and implementing effective strategies to mitigate exposure to air pollutants.

Understanding the mechanisms which inactivate airborne viruses is a current challenge. The composition of human respiratory aerosol is poorly understood and needs to be adequately investigated for use in aerovirology studies. Here, the physicochemical properties of porcine respiratory fluid (PRF) from the trachea and lungs were investigated both in bulk solutions and in aerosols. The mass ratio of Na:K in PRF compared with cell culture media (Dulbecco's Modified Eagle Medium, DMEM), which is frequently used in aerovirology studies, was significantly lower (∼2:1 vs ∼16:1). PRF contained significantly more potassium and protein than DMEM. PRF aerosols of all samples were similarly hygroscopic to human respiratory aerosol. PRF particles could nucleate with spatially separated crystals, indicating that the protein matrix was sufficiently viscous to prevent the complete coalescence of aqueous salts prior to efflorescence. The effects of these differences in compositions on the viability of viruses are currently not well understood. The virus suspensions in aerovirology studies need to be reconsidered to adequately reflect a real-world expiration scenario.

The impact of respiratory particle composition on the equilibrium morphology and phase are not well understood. Furthermore, the effects of these different phases and morphologies on the viability of viruses embedded within these particles are equally unknown. Physiologically relevant respiratory fluid analogues were constructed, and their hygroscopic behavior were measured using an ensemble technique. A relationship between hygroscopicity and protein concentration was determined, providing additional validation to the high protein content of respiratory aerosol measured in prior works (>90%). It was found that the salt component of the respiratory particles could crystallize as a single crystal, multiple crystals, or would not crystallize at all. It was found that dried protein particles at indoor-relevant climatic conditions could exist separately in a glassy (~77% of particles) or viscoelastic state (~23% of particles). The phase state and morphology of respiratory particles may influence the viability of embedded pathogens. We recommend that pathogen research aiming to mimic the native composition of respiratory fluid should use a protein concentration of at least 90% by solute volume to improve the representativity of the pathogen’s microenvironment.

Relative humidity (RH) can affect influenza A virus (IAV) survival. However, the mechanism driving this relationship is unknown. We hypothesized that the RH-dependent survival of airborne IAV could be predicted by the efflorescence/deliquescence divergent infectivity (EDDI) hypothesis. We determined three distinct RH response zones based on the hygroscopic growth factor of carrier aerosols. These zones were classified as the super-deliquescence zone (RH > 75%), the hysteresis zone (43% < RH < 75%), and the sub-efflorescence zone (RH < 43%). We added IAV (H3N2) to protein-enriched saline and aerosolized it into sub-efflorescence or superdeliquescence zone air, yielding aerosols in the effloresced or noneffloresced state, respectively. We then adjusted the RH to an ergonomically comfortable RH (60%). Fifteen minutes post-aerosolization, the surviving fractions (arithmetic means ± standard errors) of virus were higher in effloresced aerosols (9.5 ± 0.5%) than in non-effloresced aerosols (0.40 ± 0.05%). A virus suspension was also aerosolized directly into air within the super-deliquescence, hysteresis, and sub-efflorescence zones to assess the impact of the sudden change in RH from an initial 100% saturated RH to these zonal ranges. Fifteen minutes post-aerosolization, the surviving fractions were 3 ± 0.4%, 2 ± 0.1%, and 12 ± 2%, respectively. Survival following gradual adaptation to the hysteresis zone RH range was sustained in effloresced and reduced in the non-effloresced aerosols. The EDDI model predicted the survival of IAV under seasonal conditions, offering strategies for controlling indoor air infection.

The viability of airborne respiratory viruses varies with ambient relative humidity (RH). Numerous contrasting reports spanning several viruses have failed to identify the mechanism underlying this dependence. We hypothesized that an "efflorescence/deliquescence divergent infectivity" (EDDI) model accurately predicts the RH-dependent survival of airborne human rhinovirus-16 (HRV-16). We measured the efflorescence and deliquescence RH (RHE and RHD, respectively) of aerosols nebulized from a protein-enriched saline carrier fluid simulating the human respiratory fluid and found the RH range of the aerosols' hygroscopic hysteresis zone (RHE-D) to be 38-68%, which encompasses the preferred RH for indoor air (40-60%). The carrier fluid containing HRV-16 was nebulized into the sub-hysteresis zone (RH D) air, to set the aerosols to the effloresced/solid or deliquesced/liquid state before transitioning the RH into the intermediate hysteresis zone. The surviving fractions (SFs) of the virus were then measured 15 min post nebulization. SFs were also measured for aerosols introduced directly into the RH D zones without transition. SFs for transitioned aerosols in the hysteresis zone were higher for effloresced (0.17 ± 0.02) than for deliquesced (0.005 ± 0.005) aerosols. SFs for nontransitioned aerosols in the RH D zones were 0.18 ± 0.06, 0.05 ± 0.02, and 0.20 ± 0.05, respectively, revealing a V-shaped SF/RH dependence. The EDDI model's prediction of enhanced survival in the hysteresis zone for effloresced carrier aerosols was confirmed.

The impact of respiratory particle composition on the equilibrium morphology and phase are not well understood. Furthermore, the effects of these different phases and morphologies on the viability of viruses embedded within these particles are equally unknown. Physiologically relevant respiratory fluid analogues were constructed, and their hygroscopic behavior were measured using an ensemble technique. A relationship between hygroscopicity and protein concentration was determined, providing additional validation to the high protein content of respiratory aerosol measured in prior works (>90%). Atomic force microscopy was used to probe the viscoelasticity of deposited protein particles, and transmission electron microscopy was used to observe the morphology of dried composite protein/salt particles. It was found that dried protein particles at indoor-relevant climatic conditions could exist separately in a glassy or viscous semisolid state. A glassy protein shell could kinetically ‘freeze’ a particle at conditions more favorable for virus viability.

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has indirectly produced both positive and negative effects on the environment, particularly in terms of air quality. Our study aimed to determine these effects in the city of Tehran by comparing the ambient PM2.5 and PM10 levels recorded at 22 air quality monitoring stations during the outbreak (20 February–2 April 2020) with those from the corresponding period last year (20 February–3 April 2019). Contrary to expectation, the average concentrations of both the PM2.5 and the PM10 were markedly higher during the former, increasing by 20.5% and 15.7%, respectively, for the first month of the outbreak (20 February–19 March 2020) and by 23.5% and 20.0% for the subsequent Nowruz New Year holidays (from late March till early April), which resulted in overall increases of 20.5% and 16.5% for the entire period. The non-integrated responses to the pandemic, including the failure to close administrative centers and, in particular, the recommendation to maintain social distancing by reducing public transportation use (prompting citizens to travel by private vehicle), have worsened the ambient air quality in Tehran, providing an exceptional opportunity to evaluate the direct/indirect influence of air quality policies and emission control measures on PM2.5 and PM10. Because of the significant association between the lethality of coronavirus disease 2019 (COVID-19) and exposure to ambient air pollution, the rise in airborne PM2.5 during this outbreak may increase the mortality rate of SARS-CoV-2.

Whether virulent human pathogenic coronaviruses (SARS-CoV, MERS-CoV, SARS-CoV-2) are effectively transmitted by aerosols remains contentious. Transmission modes of the novel coronavirus have become a hot topic of research with the importance of airborne transmission controversial due to the many factors that can influence virus transmission. Airborne transmission is an accepted potential route for the spread of some viral infections (measles, chickenpox); however, aerosol features and infectious inoculum vary from one respiratory virus to another. Infectious virus-laden aerosols can be produced by natural human respiratory activities, and their features are vital determinants for virus carriage and transmission. Physicochemical characteristics of infectious respiratory aerosols can influence the efficiency of virus transmission by droplets. This critical review identifies studies reporting instances of infected patients producing airborne human pathogenic coronaviruses, and evidence for the role of physical/chemical characteristics of human-generated droplets in altering embedded viruses’ viability. We also review studies evaluating these viruses in the air, field studies and available evidence about seasonality patterns. Ultimately the literature suggests that a proportion of virulent human coronaviruses can plausibly be transmitted via the air, even though this might vary in different conditions. Evidence exists for respirable-sized airborne droplet nuclei containing viral RNA, although this does not necessarily imply that the virus is transmittable, capable of replicating in a recipient host, or that inoculum is sufficient to initiate infection. However, evidence suggests that coronaviruses can survive in simulated droplet nuclei for a significant time (>24 h). Nevertheless, laboratory nebulized virus-laden aerosols might not accurately model the complexity of human carrier aerosols in studying airborne viral transport. In summary, there is disagreement on whether wild coronaviruses can be transmitted via an airborne path and display seasonal patterns. Further studies are therefore required to provide supporting evidence for the role of airborne transmission and assumed mechanisms underlying seasonality., Graphical abstract Image 1, Highlights • Human respiratory activities generate respirable sized aerosols that are of adequate size to support an infectious virus. • Our knowledge of the properties of respiratory aerosols and their effects on the viability of viruses remains incomplete. • Environmental factors could directly affect the viability of virus on the embedded viruses in aerosols., Respiratory activities generate respirable sized aerosols; however, this does not reflect that the virus is transmittable or capable of replicating in a recipient host.

The relationship between air pollution and childhood cancer is inconclusive. We investigated the associations between exposure to ambient air pollution and childhood cancers in Tehran, Iran. This project included children between 1 and 15 years-of-age with a cancer diagnosis by the Center for the Control of Non Communicable Disease (n = 161) during 2007 to 2009. Controls were selected randomly within the city using a Geographic Information System (GIS) (n = 761). The cases were geocoded based on exact home addresses. Air pollution exposure of cases and random controls were estimated by a previously developed Land Use Regression (LUR) model for the 2010 calendar year. The annual mean concentrations of Particulate Matter ≤ 10 μm (PM10), nitrogen dioxide (NO2) and sulfur dioxide (SO2) in the locations of cancer cases were 101.97 μg/m3, 49.42 ppb and 38.92 ppb respectively, while in the random control group, respective mean exposures were 98.63 μg/m3, 45.98 ppb and 38.95 ppb. A logistic regression model was used to find the probability of childhood cancer per unit increase in PM10, NO2 and SO2. We observed a positive association between exposures to PM10 with childhood cancers. We did, however, observe a positive, but not statistically significant association between NO2 exposure and childhood cancer. Our study is the first to highlight an association between air pollution exposure and childhood cancer risk in Iran, however these findings require replication through future studies.

Laboratory-generated bioaerosols are widely used in aerobiology studies of viruses, however few comparisons of alternative nebulizers exist. We compared aerosol production and virus survival for a Collison nebulizer, vibrating mesh nebulizer (VMN), and hydraulic spray atomizer (HAS). We also measured the dry size distribution of the aerosols produced, calculated the droplet sizes before evaporation and the dry size distribution from normal saline solution. Dry count median diameters of 0.25, 0.63 and 0.76 µm were found for normal saline from the Collison nebulizer, VMN and HSA, respectively. The volume median diameters were 2.91, 3.2 and 2.43 µm, respectively. The effect of nebulization on the viability of two influenza A viruses (IAVs) (H1N1, H3N2) and human rhinovirus (HRV)-16, was assessed by direct nebulization into an SKC Biosampler. The HSA had least impact on surviving fractions (SFs) of H1N1 and H3N2 (89±5%, 94±3%), followed by the Collison nebulizer (82±2%, 82±3%). The VMN yielded SFs of 78±2% and 76±2%, respectively. Conversely, for HRV-16, the VMN produced higher SFs (86±15%). Our findings indicate that although the VMN had the greatest impact on IAV survival, it produced higher aerosol concentrations within the airborne-size range making it more suitable where high aerosol mass production is required.ImportanceViral respiratory tract infections cause millions of lost days of work and physician visits globally, accounting for significant morbidity and mortality. Respiratory droplet and droplet nuclei from infected hosts are the substantial potential carriers of such viruses within indoor environments. Laboratory-generated bioaerosols are applied in understanding the transmission and infection of viruses, simulating the physiological aspects of bioaerosol generation in a controlled environment. However, little comparative characterization exists for nebulizers used in infectious disease aerobiology, including Collison nebulizer, Vibrating mesh nebulizer, and hydraulic spray atomizer. This study characterized the physical features of aerosols generated by laboratory nebulizers, and their performance in producing aerosols at a size relevant to airborne transmission used in infectious disease aerobiology. We also determined the impact of nebulization mechanisms of these nebulizers on the viability of human respiratory viruses, including IAV H1N1, IAV H3N2 and HRV-16.

We conducted this systematic review to identify and appraise studies investigating the coronavirus disease 2019 (COVID-19) effect on ambient air pollution status worldwide. The review of studies was conducted using determined search terms via three major electronic databases (PubMed, Web of Science, and Scopus) according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) approach. A total of 26 full-text studies were included in our analysis. The lockdown measures related to COVID-19 pandemic caused significant decreases in the concentrations of PM2.5, NO2, PM10, SO2 and CO globally in the range of 2.9%–76.5%, 18.0%–96.0%, 6.0%–75.0%, 6.8%–49.0% and 6.2%–64.8%, respectively. However, O3 concentration increased in the range of 2.4%–252.3%. The highest decrease of PM2.5 was found in 16 states of Malaysia (76.5%), followed by Zaragoza (Spain) with 58.0% and Delhi (India) with 53.1%. The highest reduction of NO2 was found in Sale city (Morocco) with 96.0%, followed by Mumbai (India) with 75.0%, India with 70.0%, Valencia (Spain) with 69.0%, and Sao Paulo (Brazil) with 68.0%, respectively. The highest increase of O3 was recorded for Milan (Italy) with 252.3% and 169.9% during the first and third phases of lockdown measures, and for Kolkata (India) with 87% at the second phase of lockdown measures. Owing to the lockdown restrictions in the studied countries and cities, driving and public transit as a proxy of human mobilities and the factors affecting emission sources of ambient air pollution decreased in the ranges of 30–88% and 45–94%, respectively. There was a considerable variation in the reduction of ambient air pollutants in the countries and cities as the degree of lockdown measures had varied there. Our results illustrated that the COVID-19 pandemic had provided lessons and extra motivations for comprehensive implementing policies to reduce air pollution and its health effects in the future.

BTEX (benzene, toluene, ethylbenzene, and xylene) are a group of toxic organic compounds that exposure to them can cause adverse short and long terms health effects. We measured the levels of BTEX in the indoor and outdoor air of rural areas in Ardebil, Iran. We further assessed their health risks and determinants parameters. BTEX were sampled by drawing air through activated charcoal tubes, using low flow SKC pumps. Samples were extracted by adding carbon disulfide and analyzed by subjecting the aromatic fraction to GC-FID. The results indicated that the concentrations of BTEX in the indoor air were significantly higher than those of outdoor (p-value0.05). The mean indoor concentrations of benzene, toluene, ethylbenzene, and xylene were 41.69 ± 30.70, 96.73 ± 60.75, 38.73 ± 33.59, and 59.42 ± 35.99 μg m

The coronavirus disease 2019 (COVID-19) emerged in Wuhan city, China, in late 2019 and has rapidly spread throughout the world. The major route of transmission of SARS-CoV-2 is in contention, with the airborne route a likely transmission pathway for carrying the virus within indoor environments. Until now, there has been no evidence for detection of airborne severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and this may have implication for the potential spread of the COVID-19. We investigated the air of patient rooms with confirmed COVID-19 in the largest hospital in Iran, on March 17, 2020. To collect the SARS-CoV-2 particles, ten air samples were collected into the sterile standard midget impingers containing 20 mL DMEM with 100 μg/mL streptomycin, 100 U/mL penicillin and 1% antifoam reagent for 1 h. Besides, indoor particle number concentrations, CO2, relative humidity and temperature were recorded throughout the sampling duration. Viral RNA was extracted from samples taken from the impingers and Reverse-Transcription PCR (RT-PCR) was applied to confirm the positivity of collected samples based on the virus genome sequence. Fortunately, in this study all air samples which were collected 2 to 5 m from the patients' beds with confirmed COVID-19 were negative. Despite we indicated that all air samples were negative, however, we suggest further in vivo experiments should be conducted using actual patient cough, sneeze and breath aerosols in order to show the possibility of generation of the airborne size carrier aerosols and the viability fraction of the embedded virus in those carrier aerosols., Graphical abstract Unlabelled Image, Highlights • To address the airborne transmission mode of SARS-CoV-2 air samples were collected in the largest hospital in Iran. • Our results indicated that all collected samples were negative in terms of the viral RNA. • We did not detect any positive readings 2 m from the patients' beds.

Although the number of cholera infection decreased universally, climate change can potentially affect both incidence and prevalence rates of disease in endemic regions. There is considerable consistent evidence, explaining the associations between cholera and climatic variables. However, it is essentially required to compare and interpret these relationships globally. The aim of the present study was to carry out a systematic review in order to identify and appraise the literature concerning the relationship between nonanthropogenic climatic variabilities such as extreme weather- and ocean-related variables and cholera infection rates. The systematic literature review of studies was conducted by using determined search terms via four major electronic databases (PubMed, Web of Science, Embase, and Scopus) according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) approach. This search focused on published articles in English-language up to December 31, 2018. A total of 43 full-text studies that met our criteria have been identified and included in our analysis. The reviewed studies demonstrated that cholera incidence is highly attributed to climatic variables, especially rainfall, temperature, sea surface temperature (SST) and El Nino Southern Oscillation (ENSO). The association between cholera incidence and climatic variables has been investigated by a variety of data analysis methodologies, most commonly time series analysis, generalized linear model (GLM), regression analysis, and spatial/GIS. The results of this study assist the policy-makers who provide the efforts for planning and prevention actions in the face of changing global climatic variables.

The recently published article (https://doi.org/10.1016/j.envres.2018.11.046), authored by Mohsen Ansari and Mohammad Hassan Ehrampoush (2019), was read with keen interest and in detail. The article aimed to investigate the correlation between ambient fine particulate matter (PM2.5, particulate matter with aerodynamic diameter 2.5 μm and smaller) and meteorological parameters, such as temperature, humidity, precipitation and wind speed. Additionally, the World Health Organization AirQ + software, updated in 2016 by WHO European Centre for Environment and Health, was applied to estimate all-cause and also five specific causes of death (namely, ischemic heart disease (IHD), cerebrovascular disease (stroke), lung cancer (LC), chronic obstructive pulmonary disease (COPD) and acute lower respiratory infection (ALRI)) due to long-term exposure to PM2.5 in Tehran from for the year spanning March 2017 to March 2018. It was reported that the authors obtained hourly concentrations of ambient PM2.5 from Air Quality Monitoring Stations (AQMSs) operated by the Tehran Air Quality Control Company (TAQCC). Other required data also were gathered from governmental organizations, including the Statistical Centre of Iran (SCI), the Civil Registration Office of Tehran, and the Ministry of Health and Medical Education. We believe there are a number of controversial issues that should be brought to the attention of readers, especially within the materials and methods sections, including “Description of Study Area”, “Air Pollution Data Monitoring and Exposure Assessment” and “AirQ+ Software”; and in subsequent sections, we also highlight some issues impacting the interpretability of the article.

Numerous studies have found that risk of cardiovascular diseases is associated with increased blood levels of circulating markers of systemic inflammation. We investigated associations of acute exposure to bioaerosols (bacteria and fungi) with blood markers of inflammation and coagulation using panels of elderly subjects and healthy young adults. We conducted a panel study of 44 nonsmoker elderly subjects in a retirement communities and a panel study of 40 healthy young adults living in a school dormitory within Tehran city, Iran. Blood sample biomarkers were measured weekly over 6 weeks and including high sensitive C-reactive protein (hsCRP), tumor necrosis factor-soluble receptor-II (sTNF-RII), von Willebrand factor (vWF), white blood cells (WBC) count and interleukin-6 (IL-6). We found significant positive associations for IL-6 and WBC with exposure to Aspergillus spp. (As), Cladosporium spp. (Cl), Penicillium spp. (Pe), total fungi (TF) and Micrococcus spp. (MI); vWF with Cl and MI; sTNF-RII with Staphylococcus spp. (ST) in healthy young adults from the current-day and multiday averages. For elderly subjects, we observed significant positive associations for hsCRP, sTNF-RII and WBC with exposure to MI, but not with ST and total bacteria (TB). Our results showed the strongest significant positive associations for IL-6 with MI, ST and TB in elderly people. In addition, IL-6 was also positively associated with As, Cl and Pe in elderly. Also, the results showed that increase of vWF was significantly associated with bacterial and fungal aerosols, except Bacillus spp. (BA) at some lags in elderly subjects. Pooled results support the pivotal role of bioaerosols in increasing the level of some of inflammatory biomarkers, especially IL-6 and WBC in healthy young adults but possibly also in elderly people.

To investigate spatial inequality of ambient air pollutants and comparison of their heterogeneity and homogeneity across Tehran, the following quantitative indicators were utilized: coefficient of divergence (COD), the 90th percentile of the absolute differences between ambient air pollutant concentrations and coefficient of variation (CV). Real-time hourly concentrations of particulate matter (PM) and gaseous air pollutants (GAPs) of twenty-two air quality monitoring stations (AQMSs) were obtained from Tehran Air Quality Control Company (TAQCC) in 2017. Annual mean concentrations of PM2.5, PM10–2.5, and PM10 (PMX) ranged from 21.7 to 40.5, 37.3 to 75.0 and 58.0 to 110.4 μg m−3, respectively. Annual mean PM2.5 and PM10 concentrations were higher than the World Health Organization air quality guideline (WHO AQG) and national standard levels. NO2, O3, SO2 and CO annual mean concentrations ranged from 27.0 to 76.8, 15.5 to 25.1, 4.6 to 12.2 ppb, and 1.9 to 3.8 ppm over AQMSs, respectively. Our generated spatial maps exhibited that ambient PMX concentrations increased from the north into south and south-western areas as the hotspots of ambient PMX in Tehran. O3 hotspots were observed in the north and south-west, while NO2 hotspots were in the west and south. COD values of PMX demonstrated more results lower than the 0.2 cut off compared to GAPs; indicating high to moderate spatial homogeneity for PMX and moderate to high spatial heterogeneity for GAPs. Regarding CV approach, the spatial variabilities of air pollutants followed in the order of O3 (87.3%) > SO2 (65.2%) > CO (61.8%) > PM10–2.5 (52.5%) > PM2.5 (48.9%) > NO2 (48.1%) > PM10 (42.9%), which were mainly in agreement with COD results, except for NO2. COD values observed a statistically (P

Despite increasingly growth in waterpipe smoking in Tehran, so far no study has been conducted on the air quality of the waterpipe and cigarette cafés. Thirty-six cafés were selected and the concentration of three pollutants including formaldehyde, carbon monoxide and nicotine were measured in both indoor and outdoor air of cafés two times (week-day and weekend’s session). Air sampling was performed for 180 min for each pollutant. It was observed that the concentration of pollutants inside the cafés was higher during weekend session (with a higher number of “active waterpipe heads”) compared with findings during the week-day sessions. Furthermore, the concentration of pollutants in the indoor air of the cafés was significantly higher than that of the outdoors (p −5 and 61.2 × 10−5, 33.7 × 10−5 and 39.4 × 10−5, 271 × 10−5 and 322 × 10−5, and 4.80 × 10−5 and 5.90 × 10−5, respectively, which exceed the limit value by the U.S.EPA and WHO. The concentration of pollutants in the indoor air of smoking cafés in Tehran is significantly high, such that it can pose serious risks for the health of both personnel and customers. Therefore, decision makers are expected to enact applicable and strict policies so as to abate this public health risk.

Background Polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDFs) are highly toxic persistent organic pollutants (POPs), which can cause various health outcomes, such as cancer. As a part of the National and Sub-national Burden of Disease Study (NASBOD), we aimed to estimate dioxins and furans national emissions, identify their main sources, estimate daily intake doses, and assess their trend from 1990–2010 in Iran. Methods The Toolkit for Identification and Quantification of Releases of Dioxins, Furans and Other Unintentional POPs, which is developed by the United Nations Environment Programme (UNEP 2013), was used to estimate the emissions of PCDD/PCDFs from several sources into the air, water, land, residue, and other products. The daily intake doses were estimated using a linear regression of estimated emissions by UNEP Toolkit and average intake doses in other countries. Finally, the trend of PCDD/PCDFs emissions and daily intake doses were explored from 1990–2010. Results The total emissions were estimated as 960 g Toxic Equivalents (g TEQ) for 1990 and 1957 g TEQ for 2010 (18.2 and 26.8 g TEQ per million capita, respectively). The estimations suggest that albeit contribution of open burning to PCDD/PCDFs emissions has been declining from 1990 to 2010, it remained the major source of emissions in Iran contributing to about 45.8% out of total emissions in 1990 to 35.7% in 2010. We further found that PCDD/PCDFs are mostly emitted into the ambient air, followed by residue, land, products, and water. The daily intake doses were estimated to be 3.1 and 5.4 pg TEQ/kg bw/day for 1990 and 2010, respectively. We estimated an increasing trend for PCDD/PCDFs emissions and intake doses in Iran from 1990–2010. Conclusions The high levels of emissions, intake doses, and their increasing trend in Iran may pose a substantial health risk to the Iranian population. Further studies with more rigorous methods are recommended but this should not circumvent taking appropriate policy actions against these pollutants. Currently, Iran has no standard for dioxins and furans. Adaptation of the World Health Organization recommended guidelines might be an appropriate starting point to control dioxins and furans emissions.

The concentrations of bacterial and fungal bioaerosols were measured in a retirement home and a school dormitory from May 2012 to May 2013. In the present work, two active and passive methods were used for bioaerosol sampling. The results from the present work indicated that Bacillus spp., Micrococcus spp., and Staphylococcus spp. were the dominant bacterial genera, while the major fungal genera were Penicillium spp., Cladosporium spp., and Aspergillus spp. The results also indicated that the indoor-to-outdoor (I/O) ratios for total bacteria were 1.77 and 1.44 in the retirement home and the school dormitory, respectively; the corresponding values for total fungal spores were 1.23 and 1.08. The results suggested that in addition to outdoor sources, indoor sources also played a significant role in emitting bacterial and fungal bioaerosols in the retirement home and the school dormitory indoor.

Bioaerosol concentration was measured in wastewater treatment units in south of Tehran, the largest wastewater treatment plant in the Middle East. Active sampling was carried out around four operational units and a point as background. The results showed that the aeration tank with an average of 1016 CFU/m(3) in winter and 1973 CFU/m(3) in summer had the greatest effect on emission of bacterial bioaerosols. In addition, primary treatment had the highest impact on fungal emission. Among the bacteria, Micrococcus spp. showed the widest emission in the winter, and Bacillus spp. was dominant in summer. Furthermore, fungi such as Penicillium spp. and Cladosporium spp. were the dominant types in the seasons. Overall, significant relationship was observed between meteorological parameters and the concentration of bacterial and fungal aerosols.

In the present work, we investigated the characteristics of polycyclic aromatic hydrocarbons (PAHs) and metal(loid)s in indoor/outdoor PM10, PM2.5, and PM1 in a retirement home and a school dormitory in Tehran from May 2012 to May 2013. The results indicated that the annual levels of indoor and outdoor PM10 and PM2.5 were much higher than the guidelines issued by the World Health Organization (WHO). The most abundant detected metal(loid)s in PM were Si, Fe, Zn, Al, and Pb. We found higher percentages of metal(loid)s in smaller size fractions of PM. Additionally, the results showed that the total PAHs (ƩPAHs) bound to PM were predominantly (83-88%) found in PM2.5, which can penetrate deep into the alveolar regions of the lungs. In general, carcinogenic PAHs accounted for 40-47% of the total PAHs concentrations; furthermore, the smaller the particle size, the higher the percentage of carcinogenic PAHs. The percentages of trace metal(loid)s and carcinogenic PAHs in PM2.5 mass were almost twice as high as those in PM10. This can most likely be responsible for the fact that PM2.5 can cause more adverse health effects than PM10 can. The average BaP-equivalent carcinogenic (BaP-TEQ) levels both indoors and outdoors considerably exceeded the maximum permissible risk level of 1 ng/m(3) of BaP. The enrichment factors and diagnostic ratios indicated that combustion-related anthropogenic sources, such as gasoline- and diesel-fueled vehicles as well as natural gas combustion, were the major sources of PAHs and trace metal(loid)s bound to PM.

Background: Women in urban communities of Iran have the highest incidence rates of breast cancer (BC). The reasons behind this are not fully understood and many of the causes remain unexplained. Aims: The aim of this study was to examine the relationship between exposure of BC cases and exposure of the general population to long-term air pollutants in the Middle Eastern City of Tehran, Iran. Methods: Records of 1534 BC patients were obtained from Non Communicable Disease Center belong to Ministry of Health (with disease onset during 2008 to 2009). Thereafter, they were successfully geo-coded within Tehran megacity by Geographic Information System (GIS) Bureau of Iran’s Post Office based on their postal code. On the other hand, 3008 random cases were created within the city by a GIS. The individual long-term exposure to sulfur dioxide (SO2) and particulate matter ? 10 µm (PM10) air pollutants of all BC and random cases were estimated using land use regression models. Finally, bivariate correlations of the exposure of these groups were calculated. Results: The annual mean concentration of SO2 and PM10 in the BC cases were 62.9 parts per billion (ppb), and 97.6 µg/m3, respectively. While in our random points the mean exposures for mentioned pollutants were 54.1 ppb, and 93 µg/m3, respectively. The correlation of long-term exposure to SO2 between BC and random cases was positive and significant (r = 0.06, p = 0.019). Meanwhile, the correlation of long-term exposure to PM10 between BC and random cases was positive and significant (r = 0.05, p = 0.037).

Background: In addition to genetic factors, environmental factors, such as air pollution, may have a significant role in the etiology of childhood cancers (CCs). Aims: The aim of this study was to ...