The impacts of reduction in ambient fine particulate air pollution on natural-cause mortality in Taiwan.

Many epidemiologic studies have reported an association between high concentrations of fine particulate matter (PM2.5) and increased mortality rates. Concurrently an association between decreased concentration of these airborne PM2.5 pollutants and a decline in mortality frequency was noted in certain investigations globally; however, only a very few of these studies were conducted in Asia. Taiwan was found to exhibit a 30% decline in ambient PM2.5 levels over the last 20 years. The aim of this ecological investigation was to examine the contribution of annual reductions in ambient PM2.5 to changes in age-standardized natural-cause mortality rates (ASRs) in 65 townships in Taiwan from 2006 to 2020 controlling for lung cancer mortality rate, physician density, and annual household income. Data demonstrated a 0.9/105 fall in adjusted ASR for every 10 ug/m3 reduction in mean annual PM2.5 level in Taiwan during this 14-year period, suggesting a significant association between reductions in ambient PM2.5 levels and decreases in natural-cause mortality rates.

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.

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.

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.

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.

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.

Relationship between the Incidence of Dengue Virus Transmission in Traditional Market and Climatic Conditions in Kaohsiung City.

In 2014 and 2015, Southern Taiwan experienced two unprecedented outbreaks, with more than 10,000 laboratory-confirmed dengue cases in each outbreak. The present study was aimed to investigate the influence of meteorological and spatial factors on dengue outbreaks in Southern Taiwan and was conducted in Kaohsiung City, which is the most affected area in Taiwan. The distributed lag nonlinear model was used to investigate the role of climatic factors in the 2014 and 2015 dengue outbreaks. Spatial statistics in the Geographic Information System was applied to study the relationship between the dengue spreading pattern and locations of traditional markets (human motility) in the 2015 dengue outbreak. Meteorological analysis results suggested that the relative risk of dengue fever increased when the weekly average temperature was more than 15°C at lagged weeks 5 to 18. Elevated relative risk of dengue was observed when the weekly average rainfall was more than 150 mm at lagged weeks 12 to 20. The spatial analysis revealed that approximately 83% of dengue cases were located in the 1000 m buffer zone of traditional market, with statistical significance. These findings support the influence of climatic factors and human motility on dengue outbreaks. Furthermore, the study analysis may help authorities to identify hotspots and decide the timing for implementation of dengue control programs.

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.

Deaths from colon cancer among farmers in Taiwan: a mortality odds ratio study.

Few studies have examined the association between increased risk of colon cancer development and occupation of farming. Data thus far have been inconsistent with respect to a correlation between farming and colon cancer occurrence. This type of study has not been undertaken in Asia. The aim of this investigation was to utilize the mortality odds ratio (MOR) design to estimate the relative risk (RR) of mortality attributed to colon cancer in farmers in Taiwan. Utilizing Taiwan's Death Certificate Registry, data were collected on subjects who died between 1997-2009. Our study group was comprised of individuals 50 years of age and higher who died of colon cancer, while the control group consisted of subjects the same age who died of all other causes excluding cancers. Multiple logistic regression was performed to compute the MOR adjusted for gender, age at death, year of death, marital status, and urbanization levels. Of the 32,456 farmers who died, 558 were attributed to die of colon cancer. Farmers in Taiwan had a significantly lower risk of mortality from colon cancer than non-farmers (MOR = 0.85, 95% CI = 0.78-0.93), similar to estimates reported in previous meta-analyses. Occupational physical activity or higher consumption of vegetables and fruits might have contributed to the lower risk of death due to colon cancer. The basis for these observations requires further examination as it appears that lifestyle is a crucial factor in colon cancer development.

Relationship between ozone air pollution and daily suicide mortality: a time-stratified case-crossover study in Taipei.

Several studies suggested short-term exposure to air pollution might be associated with suicide mortality, although results have been inconsistent and vary depending upon the type of air contaminants. While seasonal variation associated with suicide was reported to occur and that in the spring and early summer there are peaks in ozone (O3) distribution, the relationship between these two parameters is not known. The aim of this study was to examine the potential association between O3 levels and daily mortality rate related to suicide in Taipei for the period 2004-2008 using a time-stratified case-crossover analysis. In our single pollutant model without adjustment for other pollutants, the risk of suicide increased by 11% on warm days and 15% on cool days for each interquartile range (IQR) rise in O3 concentration, respectively. The relationship was positive but did not reach significance. In our two-pollutant models, O3 remained non-significant on warm days after inclusion of one of any other ambient air contaminants into the model. However, on cool days, a significant association was found between O3 levels and enhanced risk of mortality due to suicide after nitrogen dioxide (NO2) or carbon monoxide (CO) were included. The overall positive but not significant findings of elevated risk of mortality frequently attributed to suicide on days with higher O3 levels suggest that outdoor exposures to this gaseous contaminant may contribute to increases in daily mortality rate related to suicide.

Relationship between fine particulate air pollution exposure and human adult life expectancy in Taiwan.

Among the air pollutants, particulate matter with an aerodynamic diameter less than 2.5 um (PM2.5) is of particular interest to environmental medicine as epidemiologic studies consistently reported that long-term exposure to PM2.5 is associated with increased risk of premature death in adults. Life expectancy is a well-documented and important measure of overall public health policy. However, few investigators examined the relationship between PM2.5 levels and adult life expectancy. In this Taiwan-wide study, county-level annual mean PM2.5 concentrations data were collected concomitantly with potential confounding variables including demographic and socioeconomic status, as well as smoking prevalence. Subsequently, these PM2.5 data were analyzed with respect to county-level adult life expectancy data for the period 2010 to 2017. Linear regression was used to determine the relationship between PM2.5 and life expectancy in adults. Residents residing in the counties characterized as containing higher levels of PM2.5 exhibited significantly reduced life expectancy after controlling for potential confounders. For each 10 ug/m3 increase in PM2.5 there was an estimated mean decrease in life expectancy in adults of 0.3 years. The results of this study shed light on the relationship between fine particulate air pollution exposure and risk to human health in Taiwan.

Does ambient ozone air pollution trigger suicide attempts? A case cross-over analysis in Taipei.

Epidemiologic studies indicated that exposure to ambient air pollutants was associated with increased mortality rates attributed to suicide. The objective of this study was to investigate the potential relationship between ambient ozone (O3) levels and daily number of hospital admissions for suicide attempts in Taipei for the period 2008-2012 using a time-stratified case-crossover analysis. In the single-pollutant model (without adjustment for other pollutants), the risk of committing a suicide attempt increased by 9% on warm days and 27% on cool days for each interquartile range (IQR) rise in O3 levels, respectively. The concentration of O3 was thus significantly associated with daily number of suicide attempts both on warm and cool days. In the two-pollutant models, O3 levels remained significant after the inclusion of other air pollutants (particulate matter (PM10), PM2.5, sulfur dioxide (SO2), nitrogen dioxide (NO2), and carbon monoxide (CO)) on cool days. However, on warm days, no significant correlation was found between O3 levels and reported daily number of suicide attempts. The relationship between O3 and suicide attempts appeared to be dependent upon temperature; however, the basis for these observations requires further investigation.

Accuracy of Presurgical Functional MR Imaging for Language Mapping of Brain Tumors: A Systematic Review and Meta-Analysis.

Purpose To compare functional magnetic resonance (MR) imaging for language mapping (hereafter, language functional MR imaging) with direct cortical stimulation (DCS) in patients with brain tumors and to assess factors associated with its accuracy. Materials and Methods PubMed/MEDLINE and related databases were searched for research articles published between January 2000 and September 2016. Findings were pooled by using bivariate random-effects and hierarchic summary receiver operating characteristic curve models. Meta-regression and subgroup analyses were performed to evaluate whether publication year, functional MR imaging paradigm, magnetic field strength, statistical threshold, and analysis software affected classification accuracy. Results Ten articles with a total of 214 patients were included in the analysis. On a per-patient basis, the pooled sensitivity and specificity of functional MR imaging was 44% (95% confidence interval [CI]: 14%, 78%) and 80% (95% CI: 54%, 93%), respectively. On a per-tag basis (ie, each DCS stimulation site or "tag" was considered a separate data point across all patients), the pooled sensitivity and specificity were 67% (95% CI: 51%, 80%) and 55% (95% CI: 25%, 82%), respectively. The per-tag analysis showed significantly higher sensitivity for studies with shorter functional MR imaging session times (P = .03) and relaxed statistical threshold (P = .05). Significantly higher specificity was found when expressive language task (P = .02), longer functional MR imaging session times (P < .01), visual presentation of stimuli (P = .04), and stringent statistical threshold (P = .01) were used. Conclusion Results of this study showed moderate accuracy of language functional MR imaging when compared with intraoperative DCS, and the included studies displayed significant methodologic heterogeneity. © RSNA, 2017 Online supplemental material is available for this article.

Effects of ambient air pollution exposure on frequency of hospital admissions for appendicitis in Taipei, Taiwan.

The relationship between exposure to ambient air pollutants and hospital admissions for appendicitis is not known. This study examined whether an association existed between air contaminant levels and frequency of hospital admissions for appendicitis in Taipei, Taiwan. Ambient air pollution and hospital admission data for Taipei were obtained for 2009-2013. Relative risk (RR) of hospital admissions was estimated using a case-crossover approach, controlling for weather variables, day of the week, seasonality, and long-term time trends. In the single pollutant model, on warm days (> 23°C), number of appendicitis admissions was significantly associated with particulate matter (PM2.5), nitrogen dioxide (NO2), carbon monoxide (CO), and ozone (O3). On cool days (< 23°C), a significant rise in number of admissions for appendicitis was related to PM10, NO2, and O3 concentrations. In the two-pollutant models, on warm days, NO2 and O3 were significantly associated with increased number of admissions for appendicitis when combined with each of the other pollutants. On cool days, NO2, O3, and PM10 remained significant for higher appendicitis admission cases in all two-pollutant models. In conclusion, higher levels of ambient air pollutants may be associated with increase in the risk of hospital admissions for appendicitis in Taipei.

Association between gaseous air pollution and hospital admissions for hypertension in Taipei, Taiwan.

Air pollution exposure has been reported to influence blood pressure. However, only a few epidemiological studies demonstrated association between ambient air pollution exposure and acute hypertensive events. The aim of this study was to examine the association between gaseous air pollutants exposure and hospital admissions for hypertension in Taipei, Taiwan. Data on hospital admissions for hypertension and ambient air pollution in Taipei were obtained for the 2009-2013 period. An odds ratio (OR) for number of hospital admissions for hypertension associated with each interquartile range increase in each gaseous air pollutant was calculated using a case-crossover approach, after controlling for weather variables, day of the week, seasonality, and long-term time trends. In the single-pollutant model, significant correlation was observed between number of hospital admissions for hypertension and ozone (O3) levels both on warm (>23°C) and cool (<23°C) days, with OR of 1.2 (95% confidence interval [CI] = 1.03-1.4) and 1.2 (95% CI = 1.02-1.42), respectively. No significant associations were found between levels of other gaseous pollutants and risk of hospital admissions for hypertension. In the two-pollutant model, O3 levels remained significant after inclusion of particulate matter 10 µm or less in diameter (PM10), sulfur dioxide (SO2), or carbon monoxide (CO) on warm days. On cool days, O3 levels remained significant after inclusion of air pollutants other than SO2. These findings indicated that O3 exposure may trigger a rise in blood pressure to a level that results in higher number of hospital admissions.

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.

Effects of national smoke-free legislation on the rates of preterm births and low birthweights in Taiwan.

This study evaluated the effects of partial and complete island-wide smoking bans on perinatal outcomes in Taiwan. Trends were determined in the yearly prevalence rates for preterm births and low birth weight (LBW) for a 1978 to 1997 pre-ban period, a 1998 to 2008 Phase 1 partial ban period, and a 2009 to 2016 Phase 2 complete ban period. Poisson regression with a yearly time-series model was employed to determine alterations in trends in prevalence rates for preterm births and LBW. Compared with pre-ban period, the rate ratio (RR) for Phase 1 preterm births was 0.969 (95% confidence interval [CI] = 0.968-0.971) and Phase 2 0.995 (95% CI = 0.992-0.998). The Phase 1 RR LBW fell 0.4% (95% CI = 0.2%-0.5%), but Phase 2 RR rose 1.7% (95% CI = 1.4%-2.1%). Data indicated that the risk of preterm births and LBW in Taiwan was reduced significantly after implementation of the smoking ban. These findings are in agreement with growing evidence suggesting that smoke-free legislation exerted a beneficial health effect on pregnant women and their newborn infants.