Effects of long-term exposure to ambient fine particulate air pollution on all-cause mortality in Taiwan.

According to the US Environmental Protection Agency's Integrated Science Assessment (ISA), there is a causal relationship between fine particulate matter (PM2.5) exposure and increased mortality rates. A similar association was also reported by the International Agency for Research on Cancer (IARC). While many studies are available on this relationship between PM exposure and elevated mortality frequency in Europe and North America, there are limited investigations in Asia. Thus, the aim of this study was to perform an ecological investigation to determine the relationship between exposure to ambient PM2.5 levels and all-cause mortality in 66 in Taiwan municipalities. To undertake this investigation, annual PM2.5 levels and age-standardized all-cause mortality rates were calculated for male and female residents of these areas from 2010 to 2020. Weighted-multiple regression analyses were used to obtain adjusted risk ratio (RR) controlling for possible confounding by urbanization level, physician density, and annual mean household income. Annual PM2.5 levels of each municipality were divided into tertiles. Data demonstrated that men residing in areas with intermediate tertile PM2.5 levels (21.06 to 27.29 µg/m3) and the highest tertiles levels (27.30-33.11 µg/m3) exhibited adjusted RRs of 1.06 (95% CI = 1.03-1.08) and 1.13 (95% CI = 1.10-1.16), respectively. Women in these locations displayed a similar risk, 1.03 (0.99-1.06) and 1.07 (1.04-1.11), respectively. These findings indicate that ambient exposure to PM2.5 increased risk for all-cause mortality rates in both men and women in Taiwan during this time period.

Health benefits of reducing ambient levels of fine particulate matter: a mortality impact assessment in Taiwan.

While numerous studies have found a relationship between long-term exposure to airborne fine particulate matter (PM2.5) and higher risk of death, few investigations examined the contribution that a reduction of exposure to ambient PM2.5 levels might exert on mortality rates. This study aimed to collect data on changes in annual average ambient levels of PM2.5 from 2006 to 2020 and consequent health impact in public health in 65 municipalities in Taiwan. Avoidable premature mortality was used here as an indicator of adverse health impact or health benefits. Annual PM2.5 levels were averaged for the years 2006, 2010, and 2020. In accordance with World Health Organization (WHO) methodology, differences were estimated in the number of deaths attributed to ambient PM2.5 exposure which were derived from concentration-response data from prior epidemiological studies. PM2.5 concentrations were found to have been decreased markedly throughout Taiwan over the two-decade study. As the PM2.5 concentrations fell, so was the health burden as evidenced by number of deaths concomitantly reduced from 22.4% in 2006 to 8.47% in 2020. Data demonstrated that reducing annual mean levels of PM2.5 to PM10 ug/m3 was associated with decrease in the total burden of mortality, with a 2.22-13.18% fall in estimated number of PM2.5-related deaths between 2006 and 2020. Based upon these results, these declines in ambient PM2.5 levels were correlated with significant improvement in public health (health benefits) and diminished number of deaths in Taiwan.

Risk of death from liver cancer in relation to long-term exposure to fine particulate air pollution in Taiwan.

According to the International Agency for Research on Cancer (IARC), airborne fine particulate matter (PM2.5), which is categorized as a Group I carcinogen, was found to lead to predominantly lung as well as other cancer types in humans. Hepatocellular carcinoma (HCC) is endemic in Taiwan where it is the second and fourth foremost cause of cancer deaths in men and women, respectively. Taiwan's mortality rates for liver cancer vary considerably from one region to another, suggesting that the environment may exert some influence on deaths attributed to liver cancer. The aim of this investigation was to perform an ecologic study to examine the possible link between ambient PM2.5 levels and risk of liver cancer in 66 in Taiwan municipalities. To undertake this investigation, annual PM2.5 levels and age-standardized liver cancer mortality rates were calculated for male and female residents of these areas from 2010 to 2019. Data were tested using weighted-multiple regression analyses to compute adjusted risk ratio (RR) controlling for urbanization level and physician density. Annual PM2.5 levels of each municipality were divided into tertiles. The adjusted RRs for males residing in those areas with intermediate tertile levels (21.85 to 28.21 ug/m3) and the highest tertiles levels (28.22-31.23 ug/m3) of PM2.5 were 1.29 (95% CI = 1.25-1.46) and 1.41 (95% CI = 1.36-1.46), respectively. Women in these locations shared a similar risk, 1.32 (1.25-1.4) and 1.41 (1.34-1.49), respectively. Evidence indicated that PM2.5 increased risk of mortality rates attributed to liver cancer in both men and women in Taiwan.

The impacts of reduction in ambient fine particulate (PM2.5) air pollution on life expectancy in Taiwan.

Fine particulate matter, particles less than 2.5 um in diameter (PM2.5), is an important environmental human health factor to consider. The long- and short-term influence of PM2.5 on health has been extensively studied in relation to many health outcomes, although few investigations examined the consequences of chronic ambient PM2.5 on life expectancy, which constitutes an important gauge of public human health status. Therefore, the aim of this study was to investigate the effects of reducing ambient PM2.5 levels in Taiwan on life expectancy there from 2000 to 2020. Officially reported island-wide annually average concentrations of ambient PM2.5, county-level life expectancies, and demographic and socioeconomic and proxy variable were collected for the prevalence of smoking from various national public agencies and organizations, since variables these might potentially confound life expectancy results. The relationship between changes in ambient PM2.5 levels and life expectancy were determined using linear regression. Data demonstrated that counties with greater reductions in ambient PM2.5 concentrations were associated with higher life expectancies. Adjusting for alterations in demographic and socioeconomic variables and proxy parameter, the prevalence of smoking data from a multiple regression model, it was found that a 0.3-year rise in life expectancy was noted for each 10 ug/m3 decrease in PM2.5 in those counties. Our findings show that reducing ambient PM2.5 levels play an important role for prolongation of life expectancy in Taiwan.

Ambient ozone exposure and hospitalization for substance abuse: A time-stratified case-crossover study in Taipei.

A number of studies investigating the possibility that air pollutant exposures increases the risk of adverse effects on mental health including frequency of suicide and depression, is a major growing public health concern. Human data demonstrated that exposure to various ambient air contaminants including ozone (O3) adversely affected nervous system functions. It is also well-established that substance abuse produces central nervous system dysfunctions with resultant increase in suicide rates. However, the role of substance abuse in combination with O3 exposure on mental health remained to be determined. The aim of this investigation was to conduct a time-stratified case-crossover study to examine the possible correlation between short-term ambient O3 exposure and daily hospital admissions for substance abuse, including alcohol dependence syndrome and non-dependent abuse of drugs, in Taipei from 2009 to 2013. In our single pollutant model, a 35% rise in interquartile (IQR) O3 levels on cool days and a 12% elevation on warm days was associated with increase in mental health hospitalizations. In our two-pollutant models, O3 remained significantly associated with elevated number of hospitalizations after adding any one of possible air pollutants, PM10, PM2.5, SO2, NO2, and CO, to our model on cool and warm days. Data suggested that temperature may affect the association between outdoor ambient air O3 exposure and enhanced risk of hospitalization for substance abuse. Further study is needed to better understand these findings.

Association between fine particulate air pollution and the risk of death from lung cancer in Taiwan.

Airborne fine particulate matter (PM2.5) has been classified as a Group I carcinogen leading to lung cancer in humans by the International Agency for Research on Cancer (IARC). In Taiwan, where there is a growing incidence of this disease, lung cancer is currently the leading cause of cancer-associated deaths in women and second leading cause of deaths in men. Because tobacco use is rare in Taiwan, especially amongst women, the high incidence of this type of cancer was suggested to be attributed to the other external contaminants, including airborne PM2 pollution. In this ecologic study, a possible association between ambient air PM2.5 exposure and likelihood of death attributed to lung cancer was examined in Taiwan in 66 municipalities. Annual PM2.5 levels and age-standardized lung cancer mortality rates for male and female residents were calculated for years 2010 to 2019. Weighted-multiple regression was applied to analyze our data, adjusting for level of urbanization and physician density. For males, the adjusted risk ratios (RRs) for lung cancer mortality were 1.01 for municipalities with PM2.5 levels 21.85-28.21 ug/m3 and 1.07 for municipalities with 28.22-31.23 ug/m3, compared to those with the lowest PM2.5 levels. For females, these adjusted RRs were 0.99 and 1.06, respectively. Data demonstrated an association between chronic exposure to high levels of PM2.5 and increased likelihood of death attributed to lung cancer for both men and women in Taiwan. Further studies are needed to explore the relationship between PM2.5 air pollution exposure and risk of lung cancer histologic subtype.

Effects of the implementation of a mass rapid transit system on mortality rates attributed to cardiorespiratory complications in Taipei.

Although Taipei City has encountered a fall in ambient air pollutant levels since 1996, the year its mass rapid transit (MRT) system commenced operation, no apparent study investigated changes in risks of death attributed to respiratory, cardiovascular, and cerebrovascular diseases in Taipei during this 23-year period. In order to examine the relationship between MRT and occurrence of respiratory and cardiovascular illnesses attributed to air contaminants, exposure over the 23 year duration was subdivided into the following periods: reference period 1 (1992-1995); period 2 (1996-2004), a time when there was a total track length of 67 km; period 3 (2005-2015), when the total track length was lengthened to 131.1 km; and period 4 (2016-2020), when it was further extended to 146.2 km. Taichung City, no MRT system, was used as an external reference population. The effect of Taipei's MRT system on rates of cause-specific death rates was analyzed using robust generalized Poisson regression models. After adjusting for age-standardized rates (ASRs), a decrease in relative risks (RRs) was found for non-trauma death and respiratory disease from periods 2 to 4. Even though the RRs were greater than 1.0 for cardiovascular and cerebrovascular diseases for periods 2 to 4, a downward trend was still noted in these RRs in Taipei. These findings suggest a relationship exists between air pollutant exposure and mortality. In addition, data demonstrated that implementation of the MRT in Taipei exerted beneficial health effects as evidenced by lower mortality rates.

Relationship between fine particulate air pollution and hospital admissions for depression: a case-crossover study in Taipei.

There are few apparent studies regarding the association between fine particulate matter (PM2.5) air pollution and development of depression. Data obtained from epidemiological studies are inconsistent and controversial. The aim of this case-crossover study was to examine the association between short-term exposure to PM2.5 alone and in combination with other pollutants and frequency of hospitalizations for depression from 2009 to 2013 in Taipei, Taiwan. In the single pollutant model without adjustment for other pollutants, 17% and 4% increase in admissions attributed to depression correlated with interquartile range (IQR) rise in PM2.5 levels was noted on warm and cool days, respectively. Data were also analyzed using two-pollutant models and it was found that on warm days, the association continued to be significant after including one of the following pollutants: sulfur dioxide (SO2), nitrogen dioxide (NO2), ozone (O3) or carbon monoxide (CO). On cool days, the significance was lost. In conclusion, the relationship between ambient outdoor PM2.5 exposure and rates of hospitalization for depression appeared to be temperature dependent in Taipei. Further research is needed to verify these observations as well as to distinguish the relative contributions of PM2.5 and temperature to development for hospital admissions for depression.

Change in risk of hospital admissions for ischemic heart disease after the implementation of a mass rapid transit system in Taipei.

Numerous epidemiologic studies demonstrated an association between an increase in levels of fine particles (particulate matter less than 2.5 um in diameter, PM2.5) and elevation in the number of hospital admissions for cardiovascular diseases. Air pollution levels including PM2.5 clearly decreased in Taipei City after the mass rapid transit (MRT) system began operations in 1996. The aim of this study was to investigate the extent of changes in the risk of daily hospital admissions for ischemic heart disease (IHD) over a 17-year period after the installation of a MRT system in Taipei. The full study was divided into Period 1 (1997-2000), total track length 65.1 km; Period 2 (2001-2008), total track length 75.8 km; and Period 3 (2009-2013), total track length 121.3 km. A time-stratified case-crossover analysis was conducted to estimate relative risk (RR) of hospital admissions for IHD for each 10 ug/m3 increase in PM2.5 for different periods. On cool days, the associated RR of IHD for Period 3 was consistently lower compared to period 2 in both our single- and two-pollutant models. However, the daily risk for IHD admissions was found to be significantly higher for period 3 compared to period 2 in our single-pollutant model and in our two-pollutant models (PM2.5+ SO2) on warm days. The basis for this difference is unknown. Data suggests that an MRT system may provide substantial health benefits, a finding that may be helpful to urban communities, urban planners, and public health specialists.

Association between ozone air pollution levels and hospitalizations for depression in Taipei: a time-stratified case-crossover study.

Epidemiologic studies reported an association between exposure to ambient air pollutants and increased mortality rate attributed to suicide and suicide attempts. The investigation sought to determine whether there is an association between short-term ambient ozone (O3) level exposure and daily hospital admissions for depression in Taipei from 2009 to 2013 using a time-stratified case-crossover design. In our single-pollutant model (with no adjustment for other pollutants), the % increase in daily hospital admissions for depression was 12% on warm days and 30% on cool days, per interquartile range (IQR) rise in O3 levels, respectively. Ozone levels were significantly correlated with daily number of depression admissions both on warm and cool days. In our two-pollutant models, O3 levels remained significant after adjusting for other air pollutants, including particulate matter (PM10, PM2.5), sulfur dioxide (SO2), nitrogen dioxide (NO2), and carbon monoxide (CO) both on warm and cool days. Although O3 levels tended to be higher on warm days, admissions for depression were higher on cool days, suggesting that the relationship between O3 concentrations and depression may be affected by temperature. Further study is needed to better understand these findings.

High correlation between human rhinovirus type C and children with asthma exacerbations in Taiwan.

BACKGROUND/PURPOSES: Human rhinovirus type C (HRV-C) has been associated with asthma exacerbation (AE) in children in several countries. However, in Taiwan the association between HRV, especially HRV-C, and AE in children has yet to be elucidated. We sought to investigate the prevalence of respiratory viruses in children with acute lower respiratory tract infection (ALRTI) in Taiwan and the association between different types of HRV and AE in children. METHODS: This prospective study was conducted from 2011 to 2013, and enrolled children with ALRTI, including an asthma exacerbation group (AE; n = 28) and a Non-asthma group (n = 66). Viruses were detected by culture, reverse transcription-polymerase chain reaction, and molecular sequencing of nasopharyngeal swabs. RESULTS: The prevalence of identified respiratory viruses was 78.6% in the AE group and 65.2% in the Non-asthma group. The prevalence rates of HRV and HRV-C were significantly higher in the AE group than in the Non-asthma group (67.9% vs. 33.3% in HRV, p = 0.002; and 50% vs. 15.2% in HRV-C, p < 0.001). Among the children with HRV, the prevalence of HRV-C (68.4%) was higher than that of the other types of HRV (31.6%, including HRV-A 26.3%, and HRV-B 5.3%) in the AE group but not in the Non-asthma group (40.9% vs. 59.1%). CONCLUSIONS: HRV is the most predominant viral infection responsible for pediatric AE in Taiwan, and HRV-C is responsible for more of these exacerbations than HRV-A or HRV-B.

Ambient Air Pollution and Hospital Admissions for Peptic Ulcers in Taipei: A Time-Stratified Case-Crossover Study.

Very few studies have been performed to determine whether there is a relationship between air pollution and increases in hospitalizations for peptic ulcer, and for those that have occurred, their results may not be completely relevant to Taiwan, where the mixture of ambient air pollutants differ. We performed a time-stratified case-crossover study to investigate the possible association between air pollutant levels and hospital admissions for peptic ulcer in Taipei, Taiwan. To do this, we collected air pollution data from Taiwan's Environmental Protection Agency and hospital admissions for peptic ulcer data for the years 2009-2013 from Taiwan's National Health Insurance's research database. We used conditional logistic regression to analyze the possible association between the two, taking temperature and relative humidity into account. Risk was expressed as odds ratios and significance was expressed with 95% confidence intervals. In our single pollutant model, peptic ulcer admissions were significantly associated with all pollutants (PM10, PM2.5, SO2, NO2, CO, and O3) on warm days (>23 °C). On cool days (<23 °C), peptic ulcer admissions were significantly associated with PM10, NO2, and O3. In our two-pollutant models, peptic ulcer admissions were significantly associated NO2 and O3 when combined with each of the other pollutants on warm days, and with PM10, NO2, and O3 on cool days. It was concluded that the likelihood of peptic ulcer hospitalizations in Taipei rose significantly with increases in air pollutants during the study period.

Fine particulate air pollution associated with increased risk of hospital admissions for hypertension in a tropical city, Kaohsiung, Taiwan.

The aim of this study was to assess whether a correlation exists between fine particles (PM2.5) levels and number of hospital admissions for hypertension in Kaohsiung, Taiwan. Hospital admission frequency and ambient air pollution data were obtained for Kaohsiung for 2009-2013. A time-stratified case-crossover method was used to estimate relative risk for hospital admissions, controlling for weather, day of the week, seasonality, and long-term time trends. Odds ratios and 95% confidence intervals were calculated for a 10 µg/m3 increment of PM2.5 for lags from days 0 to 6. Data showed no significant associations between PM2.5 levels and number of hypertension-related hospital admissions on warm days (>25°C). However, on cool days (<25°C), a significant positive association was found with frequency of hypertension admissions in the single-pollutant model (without adjusting for other pollutants) with a 10 µg/m3 rise in PM2.5 on day of admission (lag 0) associated with a 12% increase in number of admissions for hypertension. In the two-pollutant model, the association of PM2.5 with rate of hypertension hospitalizations remained significant after including SO2 or O3 on lag day 0. Data demonstrate that an association between short-term exposure to PM2.5 and elevated risk of hypertension-related hospital admissions may exist in Kaohsiung, Taiwan, a tropical city.

Farming and mortality rates attributed to non-Hodgkin's lymphoma in Taiwan.

Previous studies suggested an elevated risk of non-Hodgkin's lymphoma (NHL) among farmers. To date, no apparent study examined the association between farming and NHL in Asian countries. The aim of this study was to investigate whether farmers in Taiwan exhibited an increased risk of mortality attributed to NHL. To this end, a mortality odds ratio (MOR) study was conducted to estimate the relative risk of mortality attributed to NHL for farmers in Taiwan. Data on the decedents enrolled in this investigation were derived from the death certificate database for the period 1997-2009. The study group comprised individuals who died from NHL and who were 50 years or older. The control group consisted of subjects who died from all other causes, excluding cancers, in the corresponding age group. Multiple logistic regression analysis was performed to compute the MOR, with adjustments for gender, age at death, year of death, marital status, and urbanizational levels. Among 32,456 deceased farmers, 205 died due to NHL. Farmers were found to have a nonsignificantly higher MOR than nonfarmers. This risk estimate is similar to estimates in previous meta-analyses. The MOR for NHL was higher among farmers who died 65 years or older than among those who died at younger ages. The findings indicate that farming in Taiwan may increase the risk of death attributed to NHL. Exposure to pesticides might be an influential factor contributing to high risk of mortality attributed to NHL among farmers and therefore needs to be further investigated.

Short-term effects of fine particulate air pollution on hospital admissions for hypertension: A time-stratified case-crossover study in Taipei.

This study was undertaken to determine whether there was a correlation between fine particle (PM2.5) levels and hospital admissions for hypertension in Taipei, Taiwan. Hospital admissions for hypertension and ambient air pollution data for Taipei were obtained for the period from 2009 to 2013. The relative risk of hospital admissions was estimated using a case-crossover approach, controlling for weather variables, day of the week, seasonality, and long-term time trends. For the single pollutant model (without adjustment for other pollutants), the risk of hospital admissions for hypertension was estimated to increase by 12% on warm days (>23°C) and 2% on cool days (<23°C), respectively. There was no indication of an association between levels of PM2.5 and risk of hospital admissions for hypertension. In two-pollutant model, PM2.5 remained nonsignificant after inclusion of any of the other air pollutants (SO2, NO2, CO, or O3) both on warm and cool days, but a numerically greater response was seen on warm days. Data thus indicate that in Taipei, hospital admissions for hypertension occur as a consequence of factors not related to ambient air exposure.

Short-Term Effect of Coarse Particles on Daily Mortality Rate in A Tropical City, Kaohsiung, Taiwan.

Many studies examined the short-term effects of air pollution on frequency of daily mortality over the past two decades. However, information on the relationship between exposure to levels of coarse particles (PM(2.5-10)) and daily mortality rate is relatively sparse due to limited availability of monitoring data and findings are inconsistent. This study was undertaken to determine whether an association exists between PM(2.5-10) levels and rate of daily mortality in Kaohsiung, Taiwan, a large industrial city with a tropical climate. Daily mortality rate, air pollution parameters, and weather data for Kaohsiung were obtained for the period 2006-2008. The relative risk (RR) of daily mortality occurrence was estimated using a time-stratified case-crossover approach, controlling for (1) weather variables, (2) day of the week, (3) seasonality, and (4) long-term time trends. For the single-pollutant model without adjustment for other pollutants, PM(2.5-10) exposure levels showed significant correlation with total mortality rate both on warm and cool days, with an interquartile range increase associated with a 14% (95% CI = 5-23%) and 12% (95% CI = 5-20%) rise in number of total deaths, respectively. In two-pollutant models, PM(2.5-10) exerted significant influence on total mortality frequency after inclusion of sulfur dioxide (SO(2)) on warm days. On cool days, PM(2.5-10) induced significant elevation in total mortality rate when SO(2) or ozone (O(3)) was added in the regression model. There was no apparent indication of an association between PM(2.5-10) exposure and deaths attributed to respiratory and circulatory diseases. This study provided evidence of correlation between short-term exposure to PM(2.5-10) and increased risk of death for all causes.

Association between Fine Particulate Air Pollution and Daily Clinic Visits for Migraine in a Subtropical City: Taipei, Taiwan.

This study was undertaken to determine whether there was an association between fine particle (PM2.5) levels and daily clinic visits for migraine in Taipei, Taiwan. Daily clinic visits for migraine and ambient air pollution data for Taipei were obtained for the period from 2006-2011. The odds ratio of clinic visits was estimated using a case-crossover approach, controlling for weather variables, day of the week, seasonality, and long-term time trends. Generally, no significant associations between PM2.5 levels and migraine visits were observed on cool days. On warm days, however, for the single pollutant model (without adjustment for other pollutants), increased clinic visits for migraine were significantly associated with PM2.5 levels, with an interquartile range (IQR) rise associated with a 13% (95% CI = 8%-19%) elevation in number of migraine visits. In bi-pollutant model, PM2.5 remained significant after the inclusion of sulfur dioxide (SO2) or ozone (O3) on warm days. This study provides evidence that higher levels of PM2.5 increase the risk of clinic visits for migraine in Taipei, Taiwan.

Short-term effects of fine particulate air pollution on hospital admissions for respiratory diseases: a case-crossover study in a tropical city.

This study was undertaken to determine whether there was a correlation between fine particles (PM2.5) levels and hospital admissions for respiratory diseases in Kaohsiung, Taiwan. Hospital admissions for respiratory diseases including pneumonia, asthma, and chronic obstructive pulmonary disease (COPD) and ambient air pollution data for Kaohsiung were obtained for the period 2006-2010. The relative risk (RR) of hospital admissions for respiratory diseases was estimated using a case-crossover approach, controlling for weather variables, day of the week, seasonality, and chronic time trends. For the single-pollutant model (without adjustment for other pollutants), increased number of admissions for respiratory diseases were significantly associated with higher PM2.5 levels only on cool days (<25°C), with an interquartile range rise associated with a 50 (95% CI% = 45-55%), 40% (95% CI = 25-58%), and 46% (95% CI = 36-57%) elevation in frequency of admissions for pneumonia, asthma, and COPD, respectively. In the two-pollutant models, PM2.5 levels remained significant even controlling for sulfur dioxide, nitrogen dioxide, carbon monoxide, or ozone on cool days. This study provides evidence that higher levels of PM2.5 increase the risk of hospital admissions for respiratory diseases in Taiwan.

The effects of fine particulate air pollution on daily mortality: a case-crossover study in a subtropical city, Taipei, Taiwan.

This study was undertaken to determine whether there was an association between PM2.5 levels and daily mortality in Taipei, Taiwan, the largest metropolitan city with a subtropical climate. Daily mortality, air pollution, and weather data for Taipei were obtained for the period from 2006-2008. The relative risk of daily mortality was estimated using a time-stratified case-crossover approach, controlling for weather variables, day of the week, seasonality, and long-term time trends. For the single pollutant model, PM2.5 showed association with total mortality both on warm (>23 °C) and cool days (<23 °C). There is no indication of an association between PM2.5 and risk of death due to respiratory diseases both on warm and cool days. PM2.5 had effects on the risk of death from cardiovascular diseases only on cool days. In the two-pollutant models, PM2.5 remained effects on the risk of mortality for all cause and cardiovascular disease after the inclusion of SO2 and O3 both on warm and cool days. This study provides evidence that short-term exposure to PM2.5 increased the risk of death for all cause and cardiovascular disease.

Short-term effect of fine particulate air pollution on daily mortality: a case-crossover study in a tropical city, Kaohsiung, Taiwan.

Many studies have examined the short-term effects of air pollution on frequency of daily mortality over the past two decades. However, information on the relationship between levels of fine particles (PM(2.5)) and daily mortality is relatively sparse due to limited availability of monitoring data. Further the results are inconsistent. This study was undertaken to determine whether there was an association between PM(2.5) levels and daily mortality rate in Kaohsiung, Taiwan, a large industrial city with a tropical climate. Daily mortality rate, air pollution parameters, and weather data for Kaohsiung were obtained for the period from 2006 through 2008. The relative risk of daily mortality occurrence was estimated using a time-stratified case-crossover approach, controlling for (1) weather variables, (2) day of the week, (3) seasonality, and (4) long-term time trends. For the single-pollutant model (without adjustment for other pollutants), no significant effects were found between PM(2.5) and frequency of daily mortality on warm days (≥25°C). On cool days, PM(2.5) showed significant correlation with increased risk of mortality rate for all causes and circulatory diseases in single-pollutant model. There was no indication of an association between PM(2.5) and deaths due to respiratory diseases. The relationship appeared to be stronger on cool days. This study provided evidence of associations between short-term exposure to PM(2.5) and elevated risk of death for all cause and circulatory diseases.