Air pollution and daily mortality in seven major cities of Korea, 1991-1997

The relationship between ambient air pollution and daily mortality in seven major cities of Korea for the period 1991-1997 was examined. These cities account for half of the Korean population (about 22 million). The observed concentrations of sulfur dioxide (SO(2), mean=23.3 ppb), ozone (O(3), mean=23.7 ppb), and total suspended particulates (TSP, mean=77.9 microg/m(3)) during the study period were at levels below Korea's current ambient air quality standards. Generalized additive models were applied to allow for the highly flexible fitting of seasonal and long-term time trends in air pollution as well as nonlinear associations with weather variables, such as air temperature and relative humidity. In city-specific analyses, an increase of 50 ppb of SO(2) corresponded to 1-12% more deaths, given constant weather conditions. The risk of all-cause mortality was estimated to increase by 0.5-4%, with an increase in the 2-day moving average of TSP levels equal to 100 microg/m(3). In multipollutant models with pooled data, we found that the estimated risk of death by SO(2) was notably unaffected by adding the other two pollutants (TSP and O(3)) to the model and was statistically significant in various regression models. The rate ratio (RR) for SO(2) remained elevated, indicating an excess mortality of 3% 50 ppb (RR=1.03; 95% CI, 1.01-1.05). TSP's effect on mortality maintained its significance with O(3), but not with SO(2). This implies that there may be collinearity problems where TSP and SO(2) are included in the same model or that TSP may function less than SO(2) as a surrogate for fine particles in the ambient air of Korea. In conclusion, increased mortality was associated with air pollution at SO(2) levels below the current recommendation for air quality. Further research is needed to clarify the relationship between SO(2) and fine particles in Korea.     

Asthma and low level air pollution in Helsinki

The effects of relatively low levels of air pollution and weather conditions on the number of patients who had asthma attacks and who were admitted to a hospital were studied in Helsinki during a 3-y period. The number of admissions increased during cold weather (n = 4,209), especially among persons who were of working age but not among children. Even after standardization for temperature, all admissions, including emergency ward admissions, were significantly correlated with ambient air concentrations of nitrogen dioxide (NO2), nitric oxide (NO), sulfur dioxide (SO2), carbon monoxide (CO), ozone (O3), and total suspended particulates (TSP). Regression analysis revealed that NO and O3 were most strongly associated with asthma problems. Effects of air pollutants and cold were maximal if they occurred on the same day, except for O3, which had a more pronounced effect after a 1-d lag. The associations between pollutants, low temperature, and admissions were most significant among adults of working age, followed by the elderly. Among children, only O3 and NO were significantly correlated with admissions. Levels of pollutants were fairly low, the long-term mean being 19.2 micrograms/m3 for SO2, 38.6 micrograms/m3 for NO2, 22.0 micrograms/m3 or O3, and 1.3 mg/m3 for CO. In contrast, the mean concentration of TSP was high (76.3 micrograms/m3), and the mean temperature was low (+ 4.7 degrees C). These results suggest that concentrations of pollutants lower than those given as guidelines in many countries may increase the incidence of asthma attacks.     

Air pollution and ED visits for asthma in Australian children: a case-crossover analysis

OBJECTIVE: We aimed to determine the effects of ambient air pollutants on emergency department (ED) visits for asthma in children. METHODS: We obtained routinely collected ED visit data for asthma (ICD9 493) and air pollution (PM(10), PM(2.5), O(3), NO(2), CO and SO(2)) and meteorological data for metropolitan Sydney for 1997-2001. We used the time stratified case-crossover design and conditional logistic regression to model the association between air pollutants and ED visits for four age-groups (1-4, 5-9, 10-14 and 1-14 years). Estimated relative risks for asthma ED visits were calculated for an exposure corresponding to the inter-quartile range in pollutant level. We included same day average temperature, same day relative humidity, daily temperature range, school holidays and public holidays in all models. RESULTS: Associations between ambient air pollutants and ED visits for asthma in children were most consistent for all six air pollutants in the 1-4 years age-group, for particulates and CO in the 5-9 years age-group and for CO in the 10-14 years age-group. The greatest effects were most consistently observed for lag 0 and effects were greater in the warm months for particulates, O(3) and NO(2). In two pollutant models, effect sizes were generally smaller compared to those derived from single pollutant models. CONCLUSION: We observed the effects of ambient air pollutants on ED attendances for asthma in a city where the ambient concentrations of air pollutants are relatively low.     

Association between hospital emergency visits for asthma and air pollution in Valencia,Spain

OBJECTIVE: To assess the short term effect of concentrations of black smoke, sulphur dioxide (SO2), nitrogen dioxide (NO2) and ozone (O3) in ambient air on emergency room visits for asthma in the city of Valencia, Spain during the period 1994-5. METHODS: Ecological study with time series data and application of Poisson regression. Associations between number of daily emergency visits in a city''s hospital and concentrations of air pollutants were analysed taking into account potential confounding factors by the standardised protocol of the air pollution and health: a European approach (APHEA) project. RESULTS: Mean (range) daily number of emergency room visits for asthma was 1 (0-5). Concentrations of all pollutants studied remained within current air quality standards. The association between an increase of 10 micrograms/m3 in ambient air pollution and asthma, measured as a relative risk (RR) of emergency visits, was significant for NO2 24 hour mean (lag 0, RR 1.076, 95% confidence interval (95% CI) 1.020 to 1.134), NO2 hour maximum (lag 0, RR 1.037, 95% CI 1.008 to 1.066), and O3 hour maximum (lag 1, RR 1.063, CI 95% 1.014 to 1.114). The association was not significant for SO2 or for black smoke during the period analysed. The effects were not significantly different for the time of year, cold months (November to April), or warm months (May to October). CONCLUSIONS: Current concentrations of ambient air pollution in Valencia are significantly associated with emergency room visits for asthma. This association is high and more consistent for NO2 and O3 than for particulate matter and SO2 (classic pollutants).       

气态污染物与上海市浦东新区居民心脑血管疾病死亡相关性的病例交叉研究

目的评估气态污染物与浦东新区居民每日心脑血管疾病死亡的关联性,为制定相应的干预措施提供依据。方法收集浦东新区2005年1月1日-2017年12年31日的气象因素、大气污染及居民心脑血管疾病死亡资料,采用时间分层-病例交叉研究的方法,评估气态污染物对浦东新区居民心脑血管疾病死亡的影响。结果研究期间,上海市SO₂与NO₂的平均浓度分别为31.96μg/m³和45.21μg/m³。SO₂与NO₂与浦东新区居民心脑血管疾病死亡存在相关性。SO₂与NO₂的效应分别在滞后3 d(lag3)与当日(lag0)强度最大,SO₂浓度每上升10μg/m³,在滞后3d(lag3)时居民每日心脑血管疾病死亡将上升1.12%(95%CI:0.69%～1.56%);NO₂浓度每上升10μg/m³,在当日居民每日心脑血管疾病死亡将上升0.85%(95%CI...     

Long-term effects of traffic-related air pollution on mortality in a Dutch cohort (NLCS-AIR study)

BACKGROUND: Several studies have found an effect on mortality of between-city contrasts in long-term exposure to air pollution. The effect of within-city contrasts is still poorly understood. OBJECTIVES: We studied the association between long-term exposure to traffic-related air pollution and mortality in a Dutch cohort. METHODS: We used data from an ongoing cohort study on diet and cancer with 120,852 subjects who were followed from 1987 to 1996. Exposure to black smoke (BS), nitrogen dioxide, sulfur dioxide, and particulate matter < or = 2.5 microm (PM(2.5)), as well as various exposure variables related to traffic, were estimated at the home address. We conducted Cox analyses in the full cohort adjusting for age, sex, smoking, and area-level socioeconomic status. RESULTS: Traffic intensity on the nearest road was independently associated with mortality. Relative risks (95% confidence intervals) for a 10-microg/m(3) increase in BS concentrations (difference between 5th and 95th percentile) were 1.05 (1.00-1.11) for natural cause, 1.04 (0.95-1.13) for cardiovascular, 1.22 (0.99-1.50) for respiratory, 1.03 (0.88-1.20) for lung cancer, and 1.04 (0.97-1.12) for mortality other than cardiovascular, respiratory, or lung cancer. Results were similar for NO(2) and PM(2.5), but no associations were found for SO(2). CONCLUSIONS: Traffic-related air pollution and several traffic exposure variables were associated with mortality in the full cohort. Relative risks were generally small. Associations between natural-cause and respiratory mortality were statistically significant for NO(2) and BS. These results add to the evidence that long-term exposure to ambient air pollution is associated with increased mortality.     

Air pollution and daily mortality in Seoul and Ulsan, Korea.

The relationship between air pollution and daily mortality for the period 1991-1995 was examined in two Korean cities, Seoul and Ulsan. The observed concentrations of sulfur dioxide (SO2; mean = 28.7 ppb), ozone (O3; mean = 29.2 ppb), and total suspended particulates (TSP; mean = 82.3 microg/m3) during the study period were at levels below Korea's current ambient air quality standards. Daily death counts were regressed separately in the two cities, using Poisson regression on SO2, O3, and/or TSP controlling for variability in the weather and seasons. When considered singly in Poisson regression models controlling for seasonal variations and weather conditions, the nonaccidental mortality associated with a 50-ppb increment in a 3-day moving average of SO2 concentrations, including the concurrent day and the preceding 2 days, was 1.078 [95% confidence interval (CI), 1.057-1.099] for Seoul and 1.051 (CI, 0.991-1.115) for Ulsan. The rate ratio was 1.051 (CI, 1.031-1.072) in Seoul and 0.999 (CI, 0. 961-1.039) in Ulsan per 100 microg/m3 for TSP, and 1.015 (CI, 1. 005-1.025) in Seoul and 1.020 (0.889-1.170) in Ulsan per 50 ppb for 1-hr maximum O3. When TSP was considered simultaneously with other pollutants, the TSP association was no longer significant. We observed independent pollution effects on daily mortality even after using various approaches to control for either weather or seasonal variables in the regression model. This study demonstrated increased mortality associated with air pollution at both SO2 and O3 levels below the current World Health Organization recommendations.     

合肥市大气污染与肺炎门诊量的时间序列研究

目的探讨大气污染物SO_2、NO_2和PM_(2.5)浓度与合肥市滨湖医院肺炎日门诊量之间的关系。方法采用时间序列分析的广义相加Poisson回归模型,在控制长期趋势、星期几效应和气象因素等混杂因素的影响后,定量分析2014年安徽省合肥市大气污染物SO_2、NO_2、PM_(2.5)日均浓度与滨湖医院肺炎日门诊量的关系及滞后效应。结果单污染物模型中,在控制了长期趋势、星期几效应和气象因素的影响后,SO_2在滞后3、4、5 d(lag3、lag4、lag5)时对肺炎日门诊量的影响有统计学意义(P0.05),NO_2滞后2、3、4、5 d(lag2、lag3、lag4、lag5)时的影响有统计学意义(P0.01),PM_(2.5)滞后3、4 d(lag3、lag4)时的影响有统计学意义(P0.05);SO_2、NO_2、PM_(2.5)的滞后效应分别在lag3、lag2、lag4时最明显,当SO_2、NO_2、PM_(2.5)浓度每升高10μg/m~3时,肺炎日门诊量分别增加1.54%(95%CI:0.28%~2.81%),1.98%(95%CI:0.89%~3.08%)和0.28%(95%CI:0.06%~0.50%)。多污染物模型中,当模型中引入两种或两种以上的污染物后,各污染物对肺炎日门诊量的效应估计值均较单污染物模型降低,但并不改变各污染物与肺炎日门诊量之间的正向关联。结论合肥市大气污染物SO_2、NO_2、PM_(2.5)浓度升高可能引起医院肺炎日门诊量增加,且有一定的滞后效应。     

苏州市恶性肿瘤日死亡率与大气主要污染物的关系

[目的]探讨大气主要污染物对居民恶性肿瘤日死亡率的影响。[方法]收集2002～2007年苏州地区恶性肿瘤日死亡人数和大气中可吸入颗粒物（PM10）、二氧化硫（SO2）、二氧化氮（NO2）以及一氧化碳（CO）等污染物日平均浓度,经时间序列法平稳化后,再运用多元线性回归法进行相关性和确定性分析。[结果]（1）该地区居民恶性肿瘤日死亡率与7天前（1ag7）的大气中SO2、NO2及当日（1ag0）PM10平均浓度存在相关（P〈0．05）,其中S02和PM10每升高10μg/m^3,恶性肿瘤死亡的相对危险度（RR）和95％可信区间（Cl）分别为1．004（1．003～1．006,P〈0．01）和1．001（1．000～1．002,P〈0．05）,日死亡率分别上升0．44％（0．29％～0．60％）和0．10％（0．01％-0．19％）;而N02则呈负相关（P〈0．01）。（2）居民恶性肿瘤日死亡率与大气污染物日平均浓度存在线性回归（P〈0．05）,回归方程为：y=4．985＋3．963[SO2]-2．878[N02]＋0．577[PM10];模型预测的结果比较准确。（3）自变量SO2浓度标化后的偏回归系数为0．392,对应变量恶性肿瘤日死亡率的影响最大。[结论]该地区居民恶性肿瘤日死亡率与大气中SO2和PM10日平均水平呈正相关,与NO2则呈负相关;控制该地区SO2的污染水平可能有利于降低居民恶性肿瘤死亡率。     

Increased resting heart rate with pollutants in a population based study

BACKGROUND: Air pollution is associated with cardiovascular mortality. Changes in the autonomic nervous system may contribute to cardiac arrhythmias and cardiovascular mortality. This study investigated the relations between air pollutant concentrations of sulphur dioxide (SO(2)), ozone (O(3)), nitric dioxide (NO(2)), and resting heart rate (RHR) in a population based study. METHODS: A sample of 863 middle aged men and women, living in Toulouse (MONICA centre) area, was randomly recruited. A cross sectional survey on cardiovascular risk factors was carried. RHR was measured twice in a sitting position after a five minute rest. Multivariate analyses with quintiles of RHR were performed using polytomous logistic regression. Models were adjusted for temperature, season, relative humidity, sex, physical activity, blood pressure, C reactive protein, and cardiovascular drugs. RESULTS: For NO(2), the OR (odds ratio) (95% CI) associated with an increase of 5 microg/m(3) in the current day of medical examination was 1.14 (1.03 to 1.25) in quintile Q5 of RHR compared with Q1, p for trend = 0.003. For SO(2), OR was 1.16 (0.94 to 1.44) in Q5 compared with Q1, p for trend = 0.05, and for O(3), OR was 0.96 (0.91 to 1.01) in Q5 compared with Q1, p for trend = 0.11. No significant association was seen when the daily mean concentration of NO(2), SO(2), and O(3) was considered during the previous day as well as when day lag 2 or 3 was considered. The cumulative concentration (three consecutive days) of O(3) is negatively associated with RHR (p for trend = 0.02). CONCLUSION: Changes in pulse rate could reflect cardiac rhythm changes and may be part of the pathophysiological link between pollution and cardiovascular mortality.     

Relative risk of death from exposure to air pollutants: a short-term (2003-2007) study in Mexicali, Baja California, México

Studies have shown associations between respiratory diseases and air pollutants in Mexicali, México; however, none have addressed relative risk (RR) of death. By using Poisson regression models, we quantified the RR by exposure for: particulate matter (PM(10), PM(2.5)), carbon monoxide (CO), nitrogen dioxide (NO(2)), ozone (O(3)), and sulfur dioxide (SO(2)) over a 5-year period and by climate (winter or summer). RRs were estimated utilizing each pollutant (single-pollutant model) on the same day as pollutant concentration were measured (lag 0) and up to 7 days later to the pollutant measurements (lag 7). Significant associations were found in RRs for one interquartile range increment of the corresponding pollutant, such as: PM(2.5) lagged 5 days in winter and for the 5-year period (RR, 1.041 and 1.028, respectively); CO lagged 1 day in winter and for the 5-year period (RR, 1.044 and 1.032, respectively); NO(2) on the current day (lag 0) in summer (RR = 1.037); and SO(2) lagged one day for the 5-year period (RR = 1.023).     

2016—2020年江西省南昌市大气污染物与儿童呼吸疾病门诊病例数的时间序列关联研究

目的 探讨江西省南昌市6种常规监测大气污染物对儿童呼吸疾病的影响。方法 选取2016－2020年江西省南昌市大气污染物、气象数据和江西省儿童医院呼吸系统日门诊量,采用时间序列Poisson分布的广义相加模型（GAM）,定量分析大气污染物与儿童呼吸系统疾病门诊病例数的相关性。 结果 研究期间大气污染物SO2、NO2、O3-8h、CO、PM2.5、PM10的日均浓度分别为11.35 μg/m3、32.80 μg/m3、 91.80 μg/m3、0.89 mg/m3、37.42 μg/m3、68.22 μg/m3。PM2.5、PM10、SO2、CO、NO2的浓度升高对儿童呼吸系统疾病日门诊量的增加存在统计学意义,均在当日（lag0）和累积滞后第7 d（lag07）效应最强,其中SO2在累积滞后（lag07）的浓度值对儿童呼吸系统疾病门诊病例数的超额危险度（ER = 9.47%,95%CI:6.78%～12.22%）最大。双污染物模型中,调整其他5种污染物后,O3-8h对儿童呼吸系统疾病门诊量的增加无统计学意义;将O3-8h引入双污染物模型后,均一定程度的增加了其他污染物的效应,SO2在O3-8h的影响下,对儿童呼吸系统疾病门诊数影响效应值最大;PM2.5、PM10、O3-8h引入双污染模型后,SO2和NO2的效应值均扩大。 结论 2016－2020年大气污染物对南昌市儿童呼吸系统疾病有统计学影响,污染物浓度的升高导致儿童呼吸系统门诊量就诊人数增加,其中SO2对门诊量影响最大。     

某低污染区大气污染物对脑血管疾病死亡的影响

目的探讨低污染地区主要大气污染物对居民脑血管病死亡的影响。方法收集2002—2007年某地区脑血管病日死亡人数和主要大气污染物日平均浓度,经时间序列法平稳化序列后,再运用多元线性回归法进行相关性和确定性分析。结果①该地区大气中二氧化硫(SO2)、二氧化氮(NO2)、一氧化碳(CO)以及空气动力学直径10μm以下的可吸入颗粒物(PM10)日平均浓度与居民脑血管疾病死亡人数之间存在显著相关(P0.05),其中大气中SO2、NO2、CO浓度每升高10μg/m3,脑血管疾病死亡的相对危险度(OR)分别增加5.65%(95%CI,4.93%～6.37%)、1.03%(95%CI,0.24%～1.82%)和0.12%(95%CI,0.09%～0.14%),而PM10则呈显著负相关(P=0.00)。②居民日脑血管疾病死亡人数与大气污染物浓度存在线性回归(P0.05),回归方程为:^y=16.917+72.092(SO2)+26.190(NO2)-15.932(PM10)+2.062(CO)。③从标化后的偏回归系数可以得出,自变量SO2浓度对应变量脑血管疾病日死亡的影响最大。结论该地区居民脑血管病死亡与大气中SO2、NO2和呈正相关,存在线性回归,其中尤以SO2的影响最大,PM10则呈负相关;控制该地区SO2的污染水平是降低居民脑血管疾病死亡率的关键。     

城市空气污染物与交通流量的关联度分析

目的探讨城市空气污染物与交通流量的关联度。方法在南宁市不同交通流量的街道进行空气采样,分析空气样品中NO2、SO2、CO、TSP浓度,并采用邓聚龙的灰色系统理论分析空气污染物浓度与交通流量的关联度。结果交通流量与SO2、NO2、CO、TSP的关联度分别为0.5764、0.6894、0.6817、0.7002,其中上述4种污染物与摩托车流量的关联度分别为0.6085、0.7290、0.7156和0.7144,与其他机动车流量的关联度分别为0.5220、0.6247、0.6051、0.6526。结论4种空气污染物浓度受交通流量影响的顺序为TSP>NO2>CO>CO2,其中摩托车流量对上述4种空气污染物的影响最大。     

The association between air pollution and heart failure, arrhythmia, embolism, thrombosis, and other cardiovascular causes of death in a time series study

In a time series study, air pollution was associated with specific cardiovascular causes of death. Deaths due to heart failure (ICD-9 428), arrhythmia (ICD-9 427), cerebrovascular causes (ICD-9 430-436), and thrombocytic causes (ICD-9 415.1, 433-4, 444, 452-3) were more strongly associated with air pollution than cardiovascular deaths (ICD-9 390-448) in general. Excess relative risks were 2.5 to 4 times larger for these categories than for total cardiovascular disease mortality. Heart failure deaths, which made up 10% of all cardiovascular deaths, were found to be responsible for about 30% of the cardiovascular deaths related to particulate matter, SO2, CO, and NO2.     

Acute effects of air pollution in Rome

Two time-series studies, aimed at evaluating the acute health effect of air pollution among Rome inhabitants, were carried out. In the first study the correlation between daily mortality (1992 to 1995) and daily concentrations of five air pollutants (particles, SO2, NO2, CO, O3) was analyzed. In the second study the association between daily levels of the same pollutants and hospital admissions for respiratory and cardiovascular disease (1995-97) was evaluated. Poisson regression models were used to estimate the association between pollutant levels and health effect variables; the models included smooth functions of day of study, mean temperature, mean humidity and indicator variables for day of the week and holidays. Daily total mortality was associated with particle average concentration on that day and with NO2 levels of one or two days before. Hospital admissions for cardiovascular disease were positively correlated to particles, SO2, NO2, e CO. Hospital admissions for respiratory disease were associated with NO2 and CO levels of the same day and of two days before among children (0-14 years) and among adults (15-64 years). Increments of ozone were associated with increments of total respiratory and of acute respiratory diseases in children (0-14 years).     

银川市空气污染物与心脑血管疾病院前急救的关联性分析

目的 探讨银川市空气污染物与心脑血管疾病院前急救之间的关联。方法 收集2018年1月1日—2020年12月31日银川市人群心脑血管疾病院前急救资料、大气污染物(PM_2.5、PM₁₀、CO、SO₂、NO_x、O₃)和气象数据(平均温度、相对湿度),并作相关性分析。采用广义相加模型(GAM),在控制了星期几效应、气象因素后,研究大气污染物对心脑血管疾病发病的效应。结果 单污染物滞后模型结果显示PM₁₀在升高一个浓度单位后,在其滞后第五天心脑血管疾病的院前急救量增加,ER为0.056 6(95%CI:0.159 0～0.973 0);而O₃浓度在升高一个单位后,在其滞后的第三天和第六天使心脑血管疾病的院前急救量有所减少,其ER值分别为-0.101 0(95%CI:-0.195 2～-0.006 7),-0.114 1(95%CI:-0.207 9～-0.020 2)。在单污染物累积滞后模型中,O₃的累积效应呈负趋势,而N...     

Long-term exposure to urban air pollution and myocardial infarction

BACKGROUND: Cohort studies have reported increased risks of cardiopulmonary mortality from long-term air pollution exposure, but the evidence is limited and inconclusive. We studied the association between long-term exposure to source-specific air pollution and myocardial infarction (MI) in a case-control study of first-time MI cases and population controls age 45 to 70 years in Stockholm county in 1992 to 1994. METHODS: Home addresses during several decades were combined with historical emission databases and dispersion models to obtain annual mean levels of pollutants from traffic and heating during 30 years for 1397 cases and 1870 controls. Nitrogen dioxide (NO2), carbon monoxide (CO), and particulate matter with an aerodynamic diameter less than 10 microm (PM10) were used as indicators of traffic emissions and sulfur dioxide (SO2) as an indicator of emissions from residential heating. RESULTS: There was no association between long-term average air pollution exposure and overall MI, but an increased risk of fatal MI was suggested, especially for out-of-hospital death. After adjustment for cardiovascular risk factors, the odds ratio for fatal MI associated with a 5th to 95th percentile difference in 30-year average exposure was 1.51 (95% confidence interval = 0.96-2.16) for NO2, 1.22 (0.98-1.52) for CO, 1.39 (0.94-2.07) for PM10, and 1.24 (0.77-2.02) for SO2. For out-of-hospital death, the odds ratio related to NO2 exposure was 2.17 (1.05-4.51). CONCLUSIONS: This study provides some support for an association between long-term air pollution exposure and fatal cardiovascular disease.     

Outdoor air pollution, low birth weight, and prematurity

This study tested the hypothesis, suggested by several recent reports, that air pollution may increase the risk of adverse birth outcomes. This study analyzed all singleton live births registered by the Czech national birth register in 1991 in 67 districts where at least one pollutant was monitored in 1990-1991 (n = 108,173). Maternal exposures to sulfur dioxide (SO(2)), total suspended particles (TSP), and nitrous oxides (NO(x)) in each trimester of pregnancy were estimated as the arithmetic means of all daily measurements taken by all monitors in the district of birth of each infant. Odds ratios of low birth weight (< 2,500 g), prematurity (< 37 weeks of gestation), and intrauterine growth retardation (IUGR; < 10th percentile of birth weight for gestational age and sex) were estimated by robust logistic regression. The median (and 25th and 75th percentile) trimester exposures were 32 (18, 56) microg/m(3) for SO(2); 72 (55, 87) microg/m(3) for TSP; and 38 (23, 59) microg/m(3) for NO(x). Low birth weight (prevalence 5.2%) and prematurity (prevalence 4.8%) were associated with SO(2) and somewhat less strongly with TSP. IUGR was not associated with any pollutant. The effects on low birth weight and prematurity were marginally stronger for exposures in the first trimester, and were not attenuated at all by adjustment for socioeconomic factors or the month of birth. Adjusted odds ratios of low birth weight were 1.20 [95% confidence interval (CI), 1.11-1.30] and 1.15 (CI, 1.07-1.24) for a 50 microg/m(3) increase in SO(2) and TSP, respectively, in the first trimester; adjusted odds ratios of prematurity were 1.27 (CI, 1.16-1.39) and 1.18 (CI, 1.05-1.31) for a 50 microg/m(3) increase in SO(2) and TSP, respectively, in the first trimester. Low gestational age accounted for the association between SO(2) and low birth weight. These findings provide further support for the hypothesis that air pollution can affect the outcome of pregnancy.     

Association between maternal exposure to ambient air pollutants during pregnancy and fetal growth restriction

Previous research demonstrated consistent associations between ambient air pollution and emergency room visits, hospitalizations, and mortality. Effect of air pollution on perinatal outcomes has recently drawn more attention. We examined the association between intrauterine growth restriction (IUGR) among singleton term live births and sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), ozone (O3), and fine particles (PM2.5) present in ambient air in the Canadian cities of Calgary, Edmonton, and Montreal for the period 1985-2000. Multiple logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for IUGR, based on average daily levels of individual pollutants over each month and trimester of pregnancy after adjustment for maternal age, parity, infant gender, season, and city of residence. A 1 ppm increase in CO was associated with an increased risk of IUGR in the first (OR=1.18; 95% CI 1.14-1.23), second (OR=1.15; 95% CI 1.10-1.19) and third (OR=1.19; 95% CI 1.14-1.24) trimesters of pregnancy, respectively. A 20 ppb increase in NO2 (OR=1.16; 95% CI 1.09-1.24; OR=1.14; 95% CI 1.06--1.21; and OR=1.16; 95% CI 1.09-1.24 in the first, second, and third trimesters) and a 10 mug/m3 increase in PM2.5 (OR=1.07; 95% CI 1.03-1.10; OR=1.06; 95% CI 1.03-1.10; and OR=1.06; 95% CI 1.03-1.10) were also associated with an increased risk of IUGR. Consistent results were found when ORs were calculated by month rather than trimester of pregnancy. Our findings add to the emerging body of evidence that exposure to relatively low levels of ambient air pollutants in urban areas during pregnancy is associated with adverse effects on fetal growth.