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Indoor air pollution is an increasing health concern, especially in enclosed environments such as underground subway stations because of increased global usage by urban populations. This study measured the indoor air quality of underground platforms at 10 metro stations of the Taipei Rapid Transit system (TRTS) in Taiwan, including humidity, temperature, carbon monoxide (CO), carbon dioxide (CO₂), formaldehyde (HCHO), total volatile organic compounds (TVOCs), ozone (O₃), airborne particulate matter (PM 10 and PM 2.5 ), bacteria and fungi. Results showed that the CO₂, CO and HCHO levels met the stipulated standards as regulated by Taiwan's Indoor Air Quality Management Act (TIAQMA). However, elevated PM 10 and PM 2.5 levels were measured at most stations. TVOCs and bacterial concentrations at some stations measured in summer were higher than the regulated standards stipulated by Taiwan's Environmental Protection Administration. Further studies should be conducted to reduce particulate matters, TVOCs and bacteria in the air of subway stations., Competing Interests: The authors declare no conflict of interest.

Several studies have demonstrated that millions of people globally are potentially exposed to volcanic gases. Hydrogen sulfide is a typical gas in volcanic and geothermal areas. The gas is toxic at high concentrations that predominantly affects the nervous, cardiovascular, and respiratory systems. The WHO air quality guideline for hydrogen sulfide is 150 microg m(-3) (105 ppb). The northwest part of Taipei is surrounded by sulfur-rich geothermal and hot springs. Active fumaroles and bubbling springs around the geothermal area emit acidic gases. In combination with automobile emissions, the pollution of acid aerosols is characteristic of the metropolis. This study considered sulfur-rich geothermal, suburban and downtown locations of this metropolis to evaluate geothermally emitted acid aerosol and H(2)S pollution. Acid aerosols were collected using a honeycomb denuder filter pack sampling system (HDS), and then analyzed by ion chromatography (IC). Results indicated that long-term geothermal emissions, automobile emissions and photochemical reactions have led to significant variations in air pollution among regions of metropolitan Taipei. The highest H(2)S concentration was 1705 ppb in the geothermal area with low traffic density and the mean concentration was 404.06 ppb, which was higher than WHO guideline and might cause eye irritation. The SO(2) concentrations were relatively low (mean concentration was 3.9 ppb) in this area. It may partially result from the chemical reduction reaction in the geothermal emission, which converted the SO(2) gas into SO(4)(2-) and H(2)S. Consequently, very high sulfate concentrations (mean concentration higher than 25.0 microg m(-3)) were also observed in the area. The geothermal areas also emitted relatively high levels of aerosol acidity, Cl(-), F(-), PO(4)(3-), and N-containing aerosols. As a result, concentrations of HNO(3), NO(2)(-), PO(4)(3-), and SO(4)(2-) in metropolitan Taipei are significantly higher than those in other urban areas considered in other studies. These results provide evidence that geothermal emissions represent a significant source of acid aerosols in metropolitan Taipei. Therefore, in this metropolitan area, the combined health effects of air pollutants from automobiles and geothermal emissions should be particular concern., (Crown Copyright 2010. Published by Elsevier Inc. All rights reserved.)

The purpose of this study was to determine if elevated ambient exposure to incinerator generated polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) may affect birth outcomes of exposed infants born in Taipei metropolitan areas, Taiwan. The relationships between exposure to elevated PCDD/Fs concentration and various birth outcomes including birth weight, gestational age, and proportion of females were cross-sectionally assessed in 1991 (one year before the incinerator started to operate) and 1997 (five years later), respectively. We used the US EPA Industrial Source Complex Model-Sort Term modeling technique to determine the ambient PCDD/Fs concentrations in the study areas, in which 40 districts with annual averaged PCDD/Fs exposure of > or = 0.03 pg TEQ/m3 were considered as the exposed areas and another 40 districts with an estimated concentration of zero were randomly selected as reference areas. Information on birth outcomes was retrieved from the Taiwan's Birth Registry. A total of 6697 and 6282 neonates were included in the analysis for 1991 and 1997, respectively. After controlling for potential confounders, the results showed that the odds ratios (ORs) of low birth weight (< 2500 g) for higher exposures were 0.94 (> 0.05 pg TEQ/m3) and 091 (0.03-0.05 pg TEQ/m3) in 1991 and were 1.07 (> 0.05 pg TEQ/m3) and 1.06 (0.03-0.05 pg TEQ/m3) in 1997. The corresponding ORs were 1.05/0.86 (1991) and 1.12/1.22 (1997) for preterm (< 37 completed weeks of gestation), as well as 0.95/1.00 (1991) and 0.95/0.90 (1997) for female births. The above ORs were all close to unity and were statistically insignificant. When birth weight was analyzed as a continuous variable, the difference in mean birth weight between exposed group (> 0.03 pg TEQ/m3) and reference group decreased from 3.02 g in 1991 to -5.87 g in 1997. Analysis of continuous data also showed that the mean difference in gestational age between exposed and reference areas decreased from 0.05 weeks in 1991 to -0.09 week (p<0.05) in 1997. This study tends to conclude that the incinerator generated dioxin poses little effects on birth weight and female birth, but might pose small effects on gestational age. If the observed adverse effects turn out to be real, the measures now taken for improvement of abatement of waste gases seem to be a wise thing to do.

This study involved sampling over 1 year of data on exposure to acid aerosols in the geothermal area of metropolitan Taipei. The temporal and spatial variations of the concentrations of acid aerosols were assessed by sampling at three sites: A, B, and C. Results indicate that the SO2 concentrations lead the concentrations of other acid aerosols at site C because two active fumaroles surround this site. The mean SO2 concentrations at sites A, B, and C were 2.4, 2.4, and 6.2 ppb. Previous studies have found that H2S levels were highest at site C. However, the SO4(-2) and H+ concentrations among the three sites were similar. The mean aerosol SO4(-2) concentrations were 7.0, 5.7, and 5.7 microg m(-3) at sites A, B, and C, respectively; their H+ concentrations were 5.5, 4.2, and 5.4 nmol m(-3). No seasonal variations are observed for most of the acid aerosols in the geothermal area except that the types of hot spring affect the SO4(-2) concentration nearby. The different seasonal fluctuation among the sites reflect the determinant of SO4(-2) emission from different geothermal sources. Sulfur-rich aerosols and some SO2 emitted from geothermal sources are obvious. The predominance of nitrogen-containing gases (sum of NO2 + HNO2 + HNO3) over SO2 indicates the importance of the anthropogenic origin of emissions. The effect of multiple exposures to sulfur-rich aerosol (including H2S, SO2, and SO4(-2)), H+, and nitrogen-containing aerosols on the health of nearby residents warrants concern.

This study investigated the influence of petrochemical air pollution on birth weight. Birth data on 92,288 singleton infants with gestational periods of 37-44 wk born in a petrochemical industrial city (Kaohsiung, n = 31,530) with severe pollution or a nonpetrochemical industrial city (Taipei, n = 60,758) in Taiwan between 1995 and 1997 were included in this analysis. Air pollutant concentration derived from routinely monitored data showed significantly higher concentrations of SO2, O3, and PM10 in Kaohsiung. Infants with low birth weight (LBW) were significantly more prevalent in Kaohsiung (2.4%) than in Taipei (2.1%). Multivariable logistic regression analysis with adjustment for gestation age, gender, birth order, season of birth, maternal age, and maternal education further suggested that LBW risk in Kaohsiung was 13% higher than that in Taipei (odds ratio [OR] = 1.13, 95%, confidence interval [CI] = 1.03-1.24).

This retrospective cohort study investigated whether the risk of delivering full term (37-44 completed weeks of gestation) low birth weight (LBW) infants is associated with differences in exposure to air pollutants in different trimesters. Full-term infants (37 completed weeks of gestation) with a birth weight below 2500 g were classified as term LBW infants. The study infants comprised 92,288 full-term live singletons identified from the Taiwan birth registry and born in the city of Taipei or Kaoshiung in Taiwan between 1995 and 1997. Maternal exposures to various air pollutants including CO, SO2, O3, NO2, and PM10 in each trimester of pregnancy was estimated as the arithmetic means of all daily measurements taken by the air quality monitoring station nearest to the district of residence of the mother at birth. The multivariable logistic regression model with adjustment for potential confounders was used to assess the independent effect of specific air pollutants on the risk of term LBW. This study suggested a 26% increase in term LBW risk given maternal ambient exposure to SO2 concentration exceeding 11.4 ppb during pregnancy compared to low exposure (<7.1 ppb) (OR=1.26, 95% CI=1.04-1.53). Since the relative risk of term LBW was reassessed according to exposure level in each trimester, mothers exposed to >12.4 ppb of SO2 in the last trimester showed 20% higher risk (OR=1.20, 95% CI=1.01-1.41) of term LBW delivery than mothers with lower exposure (<6.8 ppb). No significant elevation ORs was observed for other air pollutants.