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Abstract Air pollution exposure has been linked to various diseases, including dementia. However, a novel method for investigating the associations between air pollution exposure and disease is lacking. The objective of this study was to investigate whether long-term exposure to ambient particulate air pollution increases dementia risk using both the traditional Cox model approach and a novel machine learning (ML) with random forest (RF) method. We used health data from a national population-based cohort in Taiwan from 2000 to 2017. We collected the following ambient air pollution data from the Taiwan Environmental Protection Administration (EPA): fine particulate matter (PM2.5) and gaseous pollutants, including sulfur dioxide (SO2), carbon monoxide (CO), ozone (O3), nitrogen oxide (NOx), nitric oxide (NO), and nitrogen dioxide (NO2). Spatiotemporal-estimated air quality data calculated based on a geostatistical approach, namely, the Bayesian maximum entropy method, were collected. Each subject's residential county and township were reviewed monthly and linked to air quality data based on the corresponding township and month of the year for each subject. The Cox model approach and the ML with RF method were used. Increasing the concentration of PM2.5 by one interquartile range (IQR) increased the risk of dementia by approximately 5% (HR = 1.05 with 95% CI = 1.04–1.05). The comparison of the performance of the extended Cox model approach with the RF method showed that the prediction accuracy was approximately 0.7 by the RF method, but the AUC was lower than that of the Cox model approach. This national cohort study over an 18-year period provides supporting evidence that long-term particulate air pollution exposure is associated with increased dementia risk in Taiwan. The ML with RF method appears to be an acceptable approach for exploring associations between air pollutant exposure and disease.

Daytime and nighttime period sampling programs were carried out using a versatile air pollutant system to collect fine (PM2.5) and coarse (PM2.5-10) particulates simultaneously at a traffic intersection near Hung-Kuang University (Taichung) during October and November 2012. Concentrations of the toxic metals in the PM2.5 and PM10 particulates were analyzed by Inductively Coupled Plasma with Atomic Emission Spectroscopy. The results indicate that the average metallic element concentrations for Zn, Cu, Cr, Mn, Fe, Pb, and Cd in the PM2.5 particles were 291, 168, 53, 37, 458, 34, and 8 ng m-3 during the daytime, respectively. The corresponding average metallic element concentrations for Zn, Cu, Cr, Mn, Fe, Pb, and Cd in the PM2.5 particles were 312, 165, 50, 36, 456, 49, and 7 ng m-3 during the nighttime, respectively. For PM2.5-10 particles, the respective concentrations were 75, 31, 9, 8, 163, 6, and 1.3 ng m-3 during the daytime; they were respective 38, 38, 12, 12, 165, 9, and 1.5 ng m-3 during the nighttime. [ABSTRACT FROM AUTHOR]

The main purpose for this study is to observe the seasonal and month variations for particulates-bound mercury Hg(p) in total suspended particulates (TSP) concentration, dry deposition at five characteristic sampling sites during years of 2009-2010 in central Taiwan. The results show that the highest and lowest monthly average particulates-bound mercury Hg(p) concentrations in TSP were occurred in Dec. and Oct. at Gao-mei (wetland), Chang-hua (downtown) and He-mei (residential) sampling site. In addition, the results show that the highest and lowest monthly average particulates-bound mercury Hg(p) dry deposition was occurred in Feb. and Oct. at Quan-xing (industrial) sampling site. This study reflected that the mean highest particulates-bound mercury Hg(p) concentrations in TSP and mean highest particulates-bound mercury Hg(p) dry deposition were occurred at Gao-mei (wetland) and Quan-xing (industrial). However, the mean lowest particulates-bound mercury Hg(p) concentrations in TSP and mean lowest particulates-bound mercury Hg(p) dry deposition were also occurred at Gao-mei (wetland). Regarding seasonal variation, the order of mean-particulates-bound mercury Hg(p) concentrations in TSP in winter and spring were Gao-mei (wetland) > Quan-xing (industrial) > Bei-shi (suburban/coastal) > Chang-hua (downtown) > He-mei (residential). Finally, the order of mean-particulates-bound mercury Hg(p) dry deposition in fall, spring and summer were Quan-xing (industrial) > Bei-shi (suburban/coastal) > Chang-hua (downtown) > He-mei (residential) > Gao-mei (wetland). [ABSTRACT FROM AUTHOR]

The possibility of using Bidens pilosa L. var. radiate Sch leaves as environmental indicators of metallic element pollution has been investigated. Samples were analyzed with respect to the following pollutants: Zn, Mn, Cu, Ni, Pb, Cd, Cr, Fe, Ca, and Mg by using inductively coupled plasma atomic emission spectrometry. The results obtained on the metallic elements had the following average composition order: Ca > Mg > Fe, Mn > Zn > Cu > Ni > Pb > Cr > Cd for plant B. pilosa L. var. radiate Sch. at HK sampling site. In addition, the metallic elements had the following average composition order: Ca > Mg > Fe > Mn, Zn > Cu > Ni > Pb > Cr > Cd for plant B. pilosa L. var. radiate Sch. at TMP sampling site. Finally, the metallic elements had the following average composition order: Ca > Mg > Fe > Zn > Mn > Cu > Pb > Ni > Cr > Cd for plant B. pilosa L. var. radiate Sch. at LH sampling site. The seasonal average composition for metallic elements Mg, Fe, and Pb were ranked highest at HK sampling site in winter. In addition, seasonal average composition for metallic elements Mn, Zn, and Cd were ranked highest at TMP sampling site in winter. Finally, seasonal average composition for metallic elements Mg, Fe, and Cu were ranked highest at LH sampling site in spring. [ABSTRACT FROM AUTHOR]

In this study, plates for downward flux and upward flux were used to measure atmospheric dry deposition fluxes for particulate mass and polycyclic aromatic hydrocarbons (PAHs) in TERC (Tsukuba), Japan. Ambient particles concentrations were also collected using a high-volume air sampler, and ambient particle size distributions between 0.01 μm and 13.1 μm were measured using a low-pressure cascade impactor to characterise the PAHs levels and dry deposition. The results indicated that the average cumulative fraction of dry deposition flux for particles and PAHs which attached with them was caused by the particle size of greater than 1.2-6.3 μm (97%). [ABSTRACT FROM AUTHOR]

Atmospheric aerosol particles and metallic concentrations, ionic species were monitored at the Experimental harbor of Taichung sampling site in this study. This work attempted to characterize metallic elements and ionic species associated with meteorological conditions variation on atmospheric particulate matter in TSP, PM2.5, PM2.5–10. The concentration distribution trend between TSP, PM2.5, PM2.5–10 particle concentration at the TH (Taichung harbor) sampling site were also displayed in this study. Besides, the meteorological conditions variation of metallic elements (Fe, Mg, Cr, Cu, Zn, Mn and Pb) and ions species (Cl−, NO3 −, SO4 2−, NH4 +, Mg2+, Ca2+ and Na+) concentrations attached with those particulate were also analyzed in this study. On non-parametric (Spearman) correlation analysis, the results indicated that the meteorological conditions have high correlation at largest particulate concentrations for TSP at TH sampling site in this study. In addition, the temperature and relative humidity of meteorological conditions that played a key role to affect particulate matter (PM) and have higher correlations then other meteorological conditions such as wind speed and atmospheric pressure. The parameter temperature and relative humidity also have high correlations with atmospheric pollutants compared with those of the other meteorological variables (wind speed, atmospheric pressure and prevalent wind direction). In addition, relative statistical equations between pollutants and meteorological variables were also characterized in this study. [ABSTRACT FROM AUTHOR]

This study monitored atmospheric pollutants during high wind speed (> 7 m s−1) at two sampling sites: Taichung Harbor (TH) and Wuci traffic (WT) during March 2004 to January 2005 in central Taiwan. The correlation coefficient ( R 2) between TSP, PM2.5, PM2.5−10 particle concentration vs. wind speed at the TH and WT sampling site during high wind speed (< 7 m s−1) were also displayed in this study. In addition, the correlation coefficients between TSP, PM2.5 and PM2.5−10 of ionic species vs. high wind speed were also observed. The results indicated that the correlation coefficient order was TSP > PM2.5−10 > PM2.5 for particle at both sampling sites near Taiwan strait. In addition, the concentration of Cl−, NO3 −, SO4 2−, NH4 +, Mg2+, Ca2+ and Na+ were also analyzed in this study. [ABSTRACT FROM AUTHOR]

Aerosol samples for dry deposition and total suspend particulates (TSP) were collected from August to November of 2003 in central Taiwan. Ion chromatography was used to analyze the related water-soluble ionic species (Cl−, NO3 −, SO4 2−, Na+, NH4 +, K+, Mg2+ and Ca2+). The results obtained in this study indicated that the ambient air particulate mass concentrations in the daytime period (averaged 975.4 μg m−3) were higher than the nighttime period (averaged 542.1 μg m−3). And the daytime dry deposition fluxes (averaged 58.12 μg m−2 sec−1) were about 2.2 times as that of nighttime dry deposition fluxes (averaged 26.54 μg m−2 sec−1) of the downward dry deposition. The average values downward and upward of dry deposition fluxes for the weekend period were almost higher than the weekday period for either daytime or nighttime period. Furthermore, the average daytime dry deposition fluxes (averaged 26.37 μg m−2 sec−1) were also about 2.3 times as that of nighttime dry deposition fluxes (averaged 11.52 μg m−2 sec−1). Moreover, the results also indicate that SO4 2− and Ca2+ have higher average composition for total suspended particulates in the daytime period while Ca2+, SO4 2−, and Na+ have the higher average composition for total suspends particulates in the nighttime period. [ABSTRACT FROM AUTHOR]

In addition to determining the concentration and metallic constituents of particulate matter at Taichung Harbor in central Taiwan, this study attempts to characterize the mass, metallic elements, composition and concentrations of total suspended particulates (TSP), fine particles and coarse particles. Statistical approaches, such as the Spearman tests, were also adopted to determine the seasonal variations of concentrations of these pollutants. Experimental results indicate that the mean TSP, fine particulate and coarse particulate concentrations in spring and winter are higher than in summer and autumn on the western coast of central Taiwan. Spearman statistical analysis of metallic elements Mn and Pb showed high concentration coefficients for fine and coarse particulates on the western coast of central Taiwan. The order of mean metallic concentrations in TSP, coarse particulates and fine particles was Fe>Zn>Mg>Cu>Cr>Mn>Pb in TSP, Fe>Cu>Zn>Mg>Mn>Pb>Cr in coarse particulates and Fe>Cu>Mg>Pb>Zn>Mn>Cr in fine particulates. [ABSTRACT FROM AUTHOR]

The purpose of this study was to characterize metallic elements associated with atmospheric particulate matter in total suspended particulate (TSP), fine particles (particle matter with an aerodynamic diameter of <2.5 μm, PM2.5) and coarse particles (particle matter with an aerodynamic diameter of 2.5–10 μm, PM2.5–10), at high wind speed (wind speed >6 m/s) at Taichung Harbor (TH) and Wuci traffic (WT) in central Taiwan from March to December 2004. The correlation coefficient (R2) between TSP, coarse, fine particulate concentrations versus wind speed at the TH and WT sampling site during high wind speed (>6 m/s) are shown in this study. In addition, the correlation coefficients between TSP, coarse and fine particles of metallic species versus high wind speed were also observed. The results indicated that the correlation coefficient order was TSP> voarse>fine for particles at both sampling sites during high wind speed (>6 m/s) near central Taiwan. In addition, the concentrations of Fe, Zn, Mn, Cu, Pb, Cr, Mg for TSP, coarse and fine particulates were also analysed in this study. [ABSTRACT FROM AUTHOR]

A micro-orifice uniform deposit impactor (MOUDI) and a nano-MOUDI were used to measure the atmospheric coarse (PM2.5-10), fine (PM2.5), ultrafine (PM0.056-1) and nano (<0.056 μm) particle concentrations at a traffic sampling site in central Taiwan during the winter period from November 2004 to January 2005. Meanwhile, concentrations of major ionic species (Cl-, NO-3, SO2-4, NH+4, Na+, K+, Ca2+ and Mg2+) were also extracted from various particle size modes (nano, ultrafine, fine and coarse) and analysed by ion chromatography (DIONEX-100). The mass size distribution of ambient suspended particles exhibited two modes. The size ranges of the particles at these two particle size modes were between 1.0 and 1.8 μm and 3.2 and 5.6 μm, respectively. The average mass media aerodynamic diameter (MMAD) of suspended particles was 0.99 μm in this study. In addition, statistical methods, such as correlation coefficient and principal component analysis, were also used to identify the possible pollutant source for various particles size modes (nano, ultrafine, fine and coarse) during the winter months at a traffic sampling site in central Taiwan. [ABSTRACT FROM AUTHOR]

A micro-orifice uniform deposit impactor (MOUDI) and a nano-MOUDI were used to measure the atmospheric coarse (PM2.5–10), fine (PM2.5), ultrafine (PM0.056–1) and nano (>0.056 μm) particle concentrations and size distributions at a traffic sampling site in winter in central Taiwan, from November 2004 to January 2005. Concentrations of metallic elements (Fe, Mg, Cr, Zn, Pb, Cu) and major ion (SO2-4, NO-3, NH+4) in particles of various sizes (nano, ultrafine, fine and coarse) were measured. Ambient air particulates generally exhibited a bimodal size distribution in the range 0.056–10 μm. The results show that the concentrations followed the order, Fe > Mg > Cr > Zn > Pb > Cu in PM10, fine, ultrafine and nano-sized particles. Moreover, the data showed that the average metallic elements Fe and Zn have similar concentration distributions: the concentration decreased as the particle size fell in the nano size range. [ABSTRACT FROM AUTHOR]

Anthropogenic acid precursor emissions in Asia are increasing at a significant rate and this is expected to continue for the next several years. This paper comprises of studies that included sulfate, nitrate and ammonium around Asian countries (China, Korea, Japan and Taiwan) in recent years. The paper also provides the water-soluble ionic fine and coarse particulate concentrations in these Asian countries in recent years. Fine and coarse particulates in Taiwan (Kaohsiung and Talchung) and China (Nanjing and Shanghai) were found to have higher sulfate (average 18.68 and 15.75 μg/m3) and nitrate (average 12.77 and 7.71 μg/m3) concentrations than any other Asian country. The average sulfate concentrations for Japan and Korea were 7.31 and 5.84 μg/m3, respectively. The average nitrate concentrations for Japan and Korea were 6.73 and 4.65 μg/m3, respectively during the years 1998–2001. The different sample collection devices, analysis methods and pollutant concentrations are discussed in this study. The purpose of this study is to arrange the atmospheric water-soluble ionic species (SO42- and NO3-) investigations in the Asian region. The data obtained here can also help to understand the sources, concentrations, phase distribution and health impact of atmospheric water-soluble ionic species (SO42- and NO3-) in other Asian regions. [ABSTRACT FROM AUTHOR]

The characterization for watersoluble species of dry deposition flux, total suspended particulate (TSP), fine particle (particle matter with aerodynamical diameter 2.5 μm, PM2.5), coarse particle (particle matter with aerodynamical diameter 2.5–10 μm, PM2.5–10), and dry deposition velocity were studied at Taichung Harbor sampling sites of central Taiwan during February–August 2004. The average downward dry deposition flux, TSP, PM10 concentrations obtained in Taichung Harbor were about 0.51, 0.3, and 3.4 times more than those values obtained by traffic sampling site in central Taiwan. Average dry deposition velocity for mass, Cl–, NO3–, SO42–, Na+, NH4+, Mg2+, and Ca2+ were 9, 3.8, 0.3, 0.25, 0.46, 0.18, 0.51 and 2.28 cm respectively at the harbor sampling site. In general, average particle mass dry deposition velocity was about 1.8 times more than those values obtained at the traffic sampling site. Chemical analysis, also indicated that three major soluble inorganic species concentrations (sulfate+nitrate+ammonium) accounted for 59.8% and 80.6% of the PM2.5 and PM2.5–10 mass concentrations, respectively at the Taichung Harbor sampling site. [ABSTRACT FROM AUTHOR]

The concentrations of polycyclic aromatic hydrocarbons in the atmosphere were measured simultaneously at Tzu Yun Yen temple and Tung Hai University pastureland in Taichung, central Taiwan. At both sites, 24 h samplings were performed between August 2001 and December 2001. The results indicated that high molecular mass polycyclic aromatic hydrocarbons are predominant at the Tzu Yun Yen temple sampling site. Moreover, the PM2.5 (fine particulate) fraction of total polycyclic aromatic hydrocarbons was higher than that of the PM2.5-10 (coarse particulate) fraction by a factor of about 1.48 at the temple sampling site. This ratio was 1.24 for the pastureland environment. [ABSTRACT FROM AUTHOR]

Atmospheric acid aerosols were sampled by two annular denuder systems (ADS) and a micro-orifice uniform deposit impactor (MOUDI) at a traffic site in central Taiwan. Theoretical analysis showed that the relative artifact for HNO[sub3] gas sampling was about 0.53 when the initial HNO3 concentration was under 0.2 µg/m³ and should be considered carefully. The concentrations of gaseous acid at the traffic sampling site were higher than those in the other study. The size distributions of acid aerosols were unimodal for C1-, NO2- and NO3-, and bimodal for SO42-. The dominant acid ions in particles less than 18 µm were SO42-, NO3-, NO2- and C1-. [ABSTRACT FROM AUTHOR]

Two sampling sites in central Taiwan, at Hungkuang University (HKU) and Tunghai University (THU), were chosen to contrast the content of polycyclic aromatic hydrocarbons (PAHs) in the atmosphere from November 2000 to April 2001. PAHs that arise from incomplete combustion of organic materials, especially fossil fuels, are the major toxic pollutants in central Taiwan. This study aimed to analyse PAHs, by using a PS-1 sampler and a gas chromatograph/mass selective detector (GC/MSD), and to identify the major sources of PAHs. At the HKU sampling site, the primary emission sources are probably vehicles and coal burning, and vehicular emissions are the primary contributor at the THU sampling site. [ABSTRACT FROM AUTHOR]

Ambient particulate measurements were carried out using TE-PUF sampling and a Universal Air Sampler between 8 March and 25 April 2001 at Taichung. Samples were collected every 6 hours beginning at 0100 LST (Local Standard Time) each day at two sites, one at a university campus and the other at a roadside. Chemical species (CI-, NO3-, SO4[2,-], Na+, NH4+,K+, Mg+,Ca[2,+],Fe, Zn, Pb, Ni) were analysed simultaneously. The main sources at the campus sampling site were identified as soil dust re-suspension, sea salt spray, secondary aerosols and zinc-related industry, and those at the traffic sampling site as soil dust re-suspension, sea salt spray, secondary aerosol and fuel combustion. The diurnal variation of all the chemical species' concentrations were also measured. The meteorological conditions and the pollutant emission sources near the sampling sites are likely impact factors. These results also showed that the short-term diurnal variation of the concentrations of chemical species in the ambient suspended particulates is useful to identify the sources and modes of formation of the particulates. [ABSTRACT FROM AUTHOR]

Concentrations of ambient suspended particulates were measured at Tzu Yun Yen temple (120°, 34', 10" E; 24°, 16', 12" N), using a Universal sampler and dry deposition plates. The temple is a characteristic incense-burning and semi-open sampling site. PM[sub2.5] concentrations for Period 1 (average 90 µg/m³) were higher than those for Period 2 (average 70 µg/m³). Results for average PM[sub2.5-10] concentrations showed equal distributions in Period 1 and Period 2. Average ratios of PM[sub2.5]/PM[sub10] were higher in Period 1 (74%) than Period 2 (71%). In addition, the suspended particulate (PM[sub10]) elements concentrations during Zhong Yuan Jie, and the first and 15th days of nong li for each month (Chinese lunar calendar) were all higher than during non-Zhong Yuan Jie and non-first and non-15th days. Furthermore, the dry deposition velocities of manganese in fine particulates (PM[sub2.5]) and suspended particulates (PM[sub10]) were 1.43 and 0.75 cm/s, respectively, and the dry deposition velocities of cadmium in fine particulates (PM[sub2.5]) and suspended particulates (PM[sub10]) were 1.86 and 0.99 cm/s, respectively. [ABSTRACT FROM AUTHOR]

Presents a study of total suspended particle (TSP) concentration, dry deposition and wind speed at the Experimental Farm of Thunghai University in Taiwan. Method used to measure the concentrations of chemical species in the atmosphere and deposited on surfaces; Relationship between TSP concentration, dry deposition flux and average wind speed; Deposition fluxes and deposition velocities for metal elements at farm and campus sampling sites.

Aerosol samples were collected by total suspended particulate (TSP) and dry deposition plate (downward, upward) from August to November in 2003 in central Taiwan. The particulate metallic elements (Fe, Pb, Zn, Cu, Mg and Mn) were also measured in this study during the summer and autumn periods of 2003. The results obtained in this study indicated that the ambient air particulate mass concentrations in the daytime period (averaged 975.4 μg/m3) were higher than the night-time period (averaged 542.1 μg/m3). And the downward dry deposition fluxes (averaged 58.12 μg/m2-sec) were about 2.2 times that of upward dry deposition fluxes (averaged 26.37 μg/m2-sec) in the daytime period. Furthermore, the average downward dry deposition fluxes (averaged 26.54 μg/m2-sec) were also about 2.3 times that of upward dry deposition fluxes (averaged 11.52 μg/m2-sec) in the night-time period. Moreover, the average downward dry deposition fluxes are greater than the upward dry deposition fluxes for all the heavy metals in either daytime or night-time period. In addition, the deposition velocity for mass, metallic elements (Fe, Pb, Zn, Cu, Mg and Mn) during daytime and night-time period were also calculated. In addition, the average TSP composition (mg/g) in the daytime period of the metallic elements (Fe, Pb, Zn, Cu, Mg and Mn) is 1.73, 0.26, 1.16, 0.28, 0.43 and 0.12 mg/g, respectively. And the average TSP composition in the night-time period of the metallic elements (Fe, Pb, Zn, Cu, Mg and Mn) is 3.02, 0.33, 1.57, 0.41, 0.58 and 0.13 mg/g, respectively at traffic sampling site of central Taiwan. [ABSTRACT FROM AUTHOR]

Focuses on a study which measured atmospheric total suspended particulate concentrations and metallic element concentrations in an urban sampling site of Taiwan. Methods; Results and discussion; Conclusion.

Discusses factors attributed to the concentration of various types of air pollutants in central Taiwan between 1998 and 2001. Indications of levels of chloride, nitrate sulfate and ammonium; Control of acidic and secondary aerosol; Assays on the organic extracts of airborne particulates.

Air quality inside Asian temples is typically poor because of the burning of incense. This study measured and analyzed concentrations of fine (PM2.5) and coarse (PM2.5-10) particulate matter and their metal elements inside a temple in central Taiwan. Experimental results showed that the concentrations of metals Cd, Ni, Pb, and Cr inside the temple were higher than those at rural, suburban, urban, and industrial areas in other studies. Three theoretical parent distributions (lognormal, Weibull, and gamma) were used to fit the measured data. The lognormal distribution was the most appropriate distribution for representing frequency distributions of PM10, PM2.5, and their metal elements. Furthermore, the central limit theorem, H-statistic-based scheme, and parametric and nonparametric bootstrap methods were used to estimate confidence intervals for mean pollutant concentrations. The estimated upper confidence limits (UCLs) of means between different methods were very consistent, because the sample coefficient of variation (CV) was <1. When the sample CV was >1, the UCL based on H-statistical method tended to overestimate the UCLs when compared with other methods. Confidence intervals for pollutant concentrations at different percentiles were evaluated using parametric and nonparametric bootstrap methods. The probabilities of pollutants exceeding a critical concentration were also calculated. [ABSTRACT FROM AUTHOR]

Investigates the ambient suspended particles and related chemical composition during the period of 1998-2001 in Taichung, Taiwan. Mass concentrations; Chemical species concentrations; Diurnal variation of suspended particles at the sampling site; Comparison of suspended particles collected in other sites around the world.