Increase In Concentration Of PM2 Research Articles

Air pollution and cardiovascular mortality in Poland: a panel time-series analysis of 80 million person-years (EP-PARTICLES study)

Abstract Introduction Air pollution is one of the leading environmental risk factors affecting the population worldwide. Studies so far mostly analysed urban and industrial areas excluding smaller towns and villages due to a lack of monitoring stations and recognition of these areas as potentially free from pollution. Our analysis focuses on Eastern Poland, one of the poorest regions of the EU, with a population of nearly 8 million people with almost half living in rural areas. We investigate the impact of "Polish smog" a new type of air pollution which - due to its composition and the conditions in which it is formed - is characterized by extremely adverse cardiovascular health effects. Purpose Analysis of the short and mid-term impact of air pollution on cardiovascular (CV) mortality. Methods We collected daily data on air pollution from the Voivodeship Inspectorate for Environmental Protection for the years 2010-2020 and used an algorithm developed in collaboration with the Department of Atmospheric and Climate Modeling at the Polish Academy of Sciences to model the average daily concentrations of pollutants in locations without available data. Causes of death with ICD-10 codes from I00 to I99 were extracted for analysis. We estimated county-specific associations of air pollution concentration with mortality using panel standard time-series with Poisson distribution regression models, adjusting for weather conditions, and short- and long-term trends in mortality. Odds ratios (ORs) with interquartile ranges (IQRs) were reported for each type of air pollutant and lag structure was analysed. Results We observed 831,246 deaths, including 377,344 due to CV diseases. The overall standardized death rate (SDR) was 533.3 cases/100,000 inhabitants/year, with an increasing trend over each year. The IQR increase in concentrations of PM2.5 (OR=1.034, 95%CI 1.029-1.04, P<0.001), benzo(a)pyrene (BaP) (OR=1.015, 95%CI 1.011-1.02; P<0.001), SO2 (OR=1.008, 95%CI 1.006-1.01; P<0.001), and NO2 (OR=1.013, 95%CI 1.01-1.016; P<0.001) were associated with an increase in CV mortality on the day of the exposure and this effect was persistent up to LAG6. The detrimental influence of pollutants was also observed in the mid-term [lag0-30 (BaP-OR=1.028, 95%CI 1.022-1.034; P<0.001), (PM2.5-OR=1.056, 95%CI 1.047-1.064; P<0.001), (SO2-OR=1.014, 95%CI 1.011-1.017; P<0.001), (NO2-OR=1.037, 95%CI 1.031-1.043; P<0.001)]. Conclusion The mortality rate due to CV diseases continues to rise. Our study highlights the negative impact of air pollution, both in the short and long term. Areas previously assumed to be free from pollution may actually be at high risk, emphasizing the need for careful monitoring of air quality. Further research should focus on identifying the most vulnerable areas and developing effective strategies to prevent the adverse health effects of air pollution on public health.

Association of Fine Particulate Matter and Its Components with Macrosomia: A Nationwide Birth Cohort Study of 336 Chinese Cities.

To examine the associations between macrosomia risk and exposure to fine particulate matter (PM2.5) and its chemical components during pregnancy, we collected birth records between 2010 and 2015 in mainland China from the National Free Preconception Health Examination Project and used satellite-based models to estimate concentrations of PM2.5 mass and five main components, namely, black carbon (BC), organic carbon (OC), nitrate (NO3-), sulfate (SO42-), and ammonium (NH4+). Associations between macrosomia risk and prenatal exposure to PM2.5 were examined by logistic regression analysis, and the sensitive subgroups were explored by stratified analyses. Of the 3,248,263 singleton newborns from 336 cities, 165,119 (5.1%) had macrosomia. Each interquartile range increase in concentration of PM2.5 during the entire pregnancy was associated with increased risk of macrosomia (odds ratio (OR) = 1.18; 95% confidence interval (CI), 1.17-1.20). Among specific components, the largest effect estimates were found on NO3- (OR = 1.36; 95% CI, 1.35-1.38) followed by OC (OR = 1.23; 95% CI, 1.22-1.24), NH4+ (OR = 1.22; 95% CI, 1.21-1.23), and BC (OR = 1.21; 95% CI, 1.20-1.22). We also that found boys, women with a normal or lower prepregnancy body mass index, and women with irregular or no folic acid supplementation experienced higher risk of macrosomia associated with PM2.5 exposure.

Maternal exposure to extreme high-temperature, particulate air pollution and macrosomia in 14 countries of Africa.

Macrosomia has increased rapidly worldwide in the past few decades, with a huge impact on health. However, the effect of PM2.5 and extreme high-temperature (EHT) on macrosomia has been ignored. This study aimed to explore the association between maternal exposure to EHT, PM2.5 and macrosomia based on the Seventh Demographic and Health Survey (DHS) in 14 countries of Africa. The study included detailed demographic information on 106 382 births and maternal. Satellite inversion models estimated monthly mean PM2.5 and mean surface temperature of 2 m (SMT2m ). Macrosomia was defined as the birth weight ≥ 4000 g. We used a Cox proportional risk regression model to estimate the association between PM2.5 , EHT and macrosomia. We further explored the susceptibility of exposure to EHT and PM2.5 at different pregnancy periods to macrosomia, and plotted the expose-response curve between PM2.5 and macrosomia risk using a restricted cubic spline function. In addition, the Interplot model was used to investigate the interaction between EHT and PM2.5 on macrosomia. Finally, some potential confounding factors were analysed by stratification. There was the positive association between EHT, PM2.5 and macrosomia, and the risk of macrosomia with the increase in concentrations of PM2.5 without clear threshold. Meanwhile, EHT and PM2.5 had a higher effect on macrosomia in middle/later and early/middle stages of pregnancy, respectively. There was a significant interaction between EHT and PM2.5 on macrosomia. Maternal exposure to EHT, PM2.5 during pregnancy was associated with an increased risk of macrosomia in Africa.

Effects of ambient air pollution on outpatient visits for psoriasis in Wuhan, China: a time-series analysis.

Psoriasis can be provoked by both external and internal factors. The effects of environmental factors on psoriasis remain unclear. To investigate the effects of air pollution on outpatient visits for psoriasis. A distributed lag nonlinear model following quasi-Poisson regression was used to evaluate the lag effects of air pollutants on psoriasis outpatient visits, adjusting for potential confounders. Stratified analyses were performed to identify potential effect modifications by sex, age and season. In total, 13 536 outpatient visits for psoriasis were recorded in Wuhan, China from 1 January 2015 to 31 December 2019. In the single-pollutant model, exposures to particulate matter (PM) smaller than 2.5 μm (PM2.5), PM smaller than 10 μm (PM10), NO2 and SO2 were found to be significantly associated with increased daily psoriasis outpatient visits. For the largest effects, a 10-μg m-3 increase in concentrations of PM2.5 (lag1), PM10 (lag1), NO2 (lag0) and SO2 (lag3) corresponded to 0.32% [95% confidence interval (CI) 0.01-0.63], 0.26% (95% CI 0.05-0.48), 0.98% (95% CI 0.01-1.96) and 2.73% (95% CI 1.01-4.47) increases in psoriasis outpatient visits, respectively. In the two-pollutant model, only NO2 showed significant and stable effects on the outpatient visits for psoriasis. Ambient air pollution, especially NO2, appears to be significantly associated with an increased risk of outpatient visits for psoriasis in Wuhan, China. Air pollution control and exposure prevention could be effective measures to relieve the symptoms of psoriasis among these patients.

Hourly Air Pollutants and Acute Coronary Syndrome Onset in 1.29 Million Patients.

Short-term exposure to ambient air pollution has been linked with daily hospitalization and mortality from acute coronary syndrome (ACS); however, the associations of subdaily (hourly) levels of criteria air pollutants with the onset of ACS and its subtypes have rarely been evaluated. We conducted a time-stratified case-crossover study among 1 292 880 patients with ACS from 2239 hospitals in 318 Chinese cities between January 1, 2015, and September 30, 2020. Hourly concentrations of fine particulate matter (PM2.5), coarse particulate matter (PM2.5-10), nitrogen dioxide (NO2), sulfur dioxide (SO2), carbon monoxide (CO), and ozone (O3) were collected. Hourly onset data of ACS and its subtypes, including ST-segment-elevation myocardial infarction, non-ST-segment-elevation myocardial infarction, and unstable angina, were also obtained. Conditional logistic regressions combined with polynomial distributed lag models were applied. Acute exposures to PM2.5, NO2, SO2, and CO were each associated with the onset of ACS and its subtypes. These associations were strongest in the concurrent hour of exposure and were attenuated thereafter, with the weakest effects observed after 15 to 29 hours. There were no apparent thresholds in the concentration-response curves. An interquartile range increase in concentrations of PM2.5 (36.0 μg/m3), NO2 (29.0 µg/m3), SO2 (9.0 µg/m3), and CO (0.6 mg/m3) over the 0 to 24 hours before onset was significantly associated with 1.32%, 3.89%, 0.67%, and 1.55% higher risks of ACS onset, respectively. For a given pollutant, the associations were comparable in magnitude across different subtypes of ACS. NO2 showed the strongest associations with all 3 subtypes, followed by PM2.5, CO, and SO2. Greater magnitude of associations was observed among patients older than 65 years and in the cold season. Null associations of exposure to either PM2.5-10 or O3 with ACS onset were observed. The results suggest that transient exposure to the air pollutants PM2.5, NO2, SO2, or CO, but not PM2.5-10 or O3, may trigger the onset of ACS, even at concentrations below the World Health Organization air quality guidelines.

Fine particulate matter air pollution and under-5 children mortality in China: A national time-stratified case-crossover study.

Under-5 mortality rate is an important indicator in Millennium Development Goals and Sustainable Development Goals. To date, no nationally representative studies have examined the effects of fine particulate matter (PM2.5) air pollution on under-5 mortality. To investigate the association of short-term exposure to PM2.5 with under-5 mortality from total and specific causes in China. We used the national Maternal and Child Health Surveillance System to identify under-5 mortality cases during the study period of 2009 to 2019. We adopted a time-stratified case-crossover study design at the individual level to capture the effect of short-term exposure to daily PM2.5 on under-5 mortality, using conditional logistic regression models. A total of 61,464 under-5 mortality cases were included. A 10μg/m3 increase in concentrations of PM2.5 on lag 0-1 d was significantly associated with a 1.15% (95%confidence interval: 0.65%, 1.65%) increase in under-5 mortality. Mortality from diarrhea, pneumonia, digestive diseases, and preterm birth were significantly associated with exposure to PM2.5. The effect estimates were larger for neonatal mortality (<28days), female children, and in warm seasons. We observed steeper slopes in lower ranges (<50μg/m3) of the concentration-response curve between PM2.5 and under-5 mortality, and positive associations remained below the 24-h PM2.5 concentration limit recommended by WHO Air Quality Guidelines and China Air Quality Standards. This nationwide case-crossover study in China demonstrated that acute exposure to PM2.5 may significantly increase the risk of under-5 mortality, with larger effects for neonates, female children, and during warm seasons. Relevant control strategies are needed to remove this roadblock to achieving under-5 mortality targets in developing countries.

Ambient Air Pollutions Are Associated with Vitamin D Status.

Evidence on the effect of ambient air pollution on vitamin D is limited. This study aimed to examine the association of air pollution exposure with serum levels of 25-hydroxyvitamin D (25OHD) using UK Biobank health datasets. A total of 448,337 subjects were included in this analysis. Land Use Regression was applied to assess individual exposures to particulate matter with diameters ≤2.5 µm (PM2.5), ≤10 µm (PM10), nitrogen dioxide (NO2), and nitrogen oxides (NOx). Linear regression models evaluated the associations between air pollutants and serum vitamin D levels after adjustment of a series of confounders. All analyzed air pollutants were negatively associated with serum vitamin 25OHD levels. After adjusting for potential confounders, a 10 μg/m3 increase in concentrations of PM2.5, PM10, NOx, and NO2 was associated with −9.11 (95%CI: −13.25 to −4.97), −2.47 (95%CI: −4.51 to −0.43), −0.56 (95%CI: −0.82 to −0.30), and −1.64 (95%CI: −2.17 to −1.10) nmol/L decrease in serum vitamin 25OHD levels, respectively. Interaction analyses suggested that the effects of air pollution were more pronounced in females. In conclusion, long-term exposures to ambient PM2.5, PM10, NOx, and NO2 were associated with vitamin D status in a large UK cohort.

Effect of Meteorological Conditions and Anthropogenic Factors on Air Concentrations of PM2.5 and PM10 Particulates on the Examples of the City of Kielce, Poland

The paper analyzes the influence of meteorological conditions (air temperature, wind speed, humidity, visibility) and anthropogenic factors (population in cities and in rural areas, road length, number of vehicles, emission of dusts and gases, coal consumption in industrial plants, number of air purification devices installed in industrial plants) on the concentration of PM2.5 and PM10 dusts in the air in the region of Kielce city in Poland. Spearman correlation coefficient was used to evaluate the relationship between the mentioned independent variables and air quality indicators. The calculated values of the correlation coefficient showed statistically significant relationships between air quality and the amount of installed air purification equipment in industrial plants. A statistically significant effect of the population in rural settlement units on the increase in air concentrations of PM2.5 and PM10 was also found, which proves the influence of the so-called low emission of pollutants on the air quality in the studied region. The analyses also revealed a statistically significant effect of road length on the decrease in PM2.5 and PM10 air content. This result indicates that a decrease in traffic intensity on particular road sections leads to an improvement in air quality. The analyses showed that despite the progressing anthropopression in the Kielce city region the air quality with respect to PM2.5 and PM10 content is improving. To verify the results obtained from statistical calculations, parametric models were also determined to predict PM2.5 and PM10 concentrations in the air, using the methods of Random Forests (RF), Boosted Trees (BT) and Support Vector Machines (SVM) for comparison purposes. The modelling results confirmed the conclusions that had been made based on previous statistical calculations.

Exposure to air pollution and renal function - an underestimated threat?

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Air pollution contributes to the premature death of approximately 428,000 citizens of Europe every year. The adverse effects of air pollution can be observed not only in respiratory, circulatory, and nervous systems but also in renal function. Purpose Our goal was to investigate the hypothesis indicating that we can observe the long-term and also short-term impact of air pollution on kidney function. Methods We reviewed medical notes of patients hospitalized between 2007-2016. We used linear, log-linear, and logistic regression models to assess the association between renal function and NO2, SO2, and PMs. Results are reported as beta (β) coefficients and odds ratios (OR) for an increase in interquartile range (IQR) concentration with 95% confidence intervals (CI). Results 3,554 patients were included into the final analysis. The median age was 66 (IQR 15) and men were in the majority (53.2%, N = 1891). Chronic kidney disease (CKD) was diagnosed in 21.5% (N = 764). The long-term increase in annual average concentration of PM2.5 (OR for IQR increase = 1.07; 95% CI 1.01 – 1.15, P = 0.037) and NO2 (OR for IQR increase = 1.05;95% CI 1.01 – 1.10, P = 0.047) resulted in an increased number of patients with CKD. In short-term observation the IQR increase in weekly PM2.5 concentration was associated with a 2% reduction in eGFR (OR = 0.98, 95%CI 0.97 – 0.99, P = 0.03) Conclusions The effects of air pollution on renal function were observed. Long- and short–term exposure to elevated air pollution levels was associated with a decrease in eGFR. The main pollutant affecting the kidneys was PM2.5.

The effect of air pollution on drivers' safety performance.

Numerous studies have determined the adverse effects of air pollution on the health, welfare, and comfort of humans. More recently, the effects of air pollution on cognitive performance of humans are also focused. However, as a group in direct exposure to air pollution, drivers are rarely studied. The present study aims to evaluate the effect of air pollution on the performance of drivers. Their performance is evaluated by observing the number of recorded accidents. The effect of pollutant concentration (primarily PM2.5) on the number of accidents is investigated in a case study in Tehran. The temperature inversion phenomenon is used as an instrumental variable in a two-stage least squares method. The results indicate that temperature inversion had a significant positive correlation with the concentration of pollutants. Considering temperature inversion as an instrumental variable for these pollutants, it is observed that 1 μg/m3 increase in concentration of PM2.5, increased the number of accidents approximately by 4% in 1 day, for the range of parameters studied. No significant relationship was observed regarding the effect of NO2 and CO on accidents during the study period.

Estimation of PM2.5 pollutant time changes and its effect on ischemic heart disease (IHD) outcome in Ahvaz city, Iran (2008–2017)

Air pollution is known today as one of the most important environmental problems in many major cities of the world due to its harmful consequences for human health and the environment. PM2.5 with a diameter of fewer than 2.5 μm can penetrate deep into the lungs and cause health concerns, including cardiovascular disease. In this study, the hourly, daily, weekly, monthly, seasonal, and annual changes of PM2.5 pollutants and its effect on cardiovascular outcome IHD (ischemic heart disease) in a period of 10 years (2008–2017) in Ahvaz were investigated. Also, air quality was investigated for PM2.5 pollutants based on air quality index (AQI). Data validation was performed using WHO criteria. The average time PM2.5 was calculated and its health effects were obtained by entering its annual data and population at-risk, baseline incidence (BI), and relative risk (RR) for IHD outcomes. The average concentration of PM2.5 pollutants in all time changes in Ahvaz was higher than the standard concentration set by WHO. The AQI showed that the city of Ahvaz did not have a good day at all during the 10-year period. Time changes and the air quality index AQI showed that 2010 was the most polluted year with 47 unhealthy (a level that may have harmful impacts on patients and members of sensitive groups) days and 27 dangerous (a level that may have a serious impact on patients and members of sensitive groups in case of acute exposure) days. Also, with the increase in the annual concentration of PM2.5, the mortality attributed to this pollutant has increased as a result of the outcome of IHD. According to the obtained results, it can be said that the air quality of Ahvaz city was in an unsuitable situation in terms of PM2.5 pollution and appropriate measures should be taken to reduce mortality due to the outcome of cardiovascular IHD. The survey requires the need to enact and enforce permissible particulate matter levels for reduce the health effect on human by relevant environmental authorities both at Federal and state levels.

The short-term effects of air pollutants on influenza-like illness in Jinan, China

BackgroundThere is valid evidence that air pollution is associated with respiratory disease. However, few studies have quantified the short-term effects of six air pollutants on influenza-like illness (ILI). This study explores the potential relationship between air pollutants and ILI in Jinan, China.MethodsDaily data on the concentration of particulate matters < 2.5 μm (PM 2.5), particulate matters < 10 μm (PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), and ozone (O3) and ILI counts from 2016 to 2017 were retrieved. The wavelet coherence analysis and generalized poisson additive regression model were employed to qualify the relationship between air pollutants and ILI risk. The effects of air pollutants on different age groups were investigated.ResultsA total of 81,459 ILI counts were collected, and the average concentrations of PM2.5, PM10, O3, CO, SO2 and NO2 were 67.8 μg/m3, 131.76 μg/ m3, 109.85 μg/ m3, 1133 μg/ m3, 33.06 μg/ m3 and 44.38 μg/ m3, respectively. A 10 μg/ m3 increase in concentration of PM2.5, PM10, CO at lag0 and SO2 at lag01, was positively associated with a 1.0137 (95% confidence interval (CI): 1.0083–1.0192), 1.0074 (95% CI: 1.0041–1.0107), 1.0288 (95% CI: 1.0127–1.0451), and 1.0008 (95% CI: 1.0003–1.0012) of the relative risk (RR) of ILI, respectively. While, O3 (lag5) was negatively associated with ILI (RR 0.9863; 95%CI: 0.9787–0.9939), and no significant association was observed with NO2, which can increase the incidence of ILI in the two-pollutant model. A short-term delayed impact of PM2.5, PM10, SO2 at lag02 and CO, O3 at lag05 was also observed. People aged 25–59, 5–14 and 0–4 were found to be significantly susceptible to PM2.5, PM10, CO; and all age groups were significantly susceptible to SO2; People aged ≥60 year, 5–14 and 0–4 were found to be significantly negative associations with O3.ConclusionAir pollutants, especially PM2.5, PM10, CO and SO2, can increase the risk of ILI in Jinan. The government should create regulatory policies to reduce the level of air pollutants and remind people to practice preventative and control measures to decrease the incidence of ILI on pollution days.

Association between prenatal exposure to air pollution and inflammatory markers in children

TPS 911: Air pollution, epigenetics, biomarkers, Exhibition Hall, Ground floor, August 26, 2019, 3:00 PM - 4:30 PM Background/Aim: Early-life exposure to ambient air pollution has been associated with adverse health effects in children but little is known about its potential effects on cytokine levels. We evaluated the association of pregnancy exposure to particulate matter with child inflammatory biomarkers in 500 mother-child pairs from the RHEA pregnancy cohort in Crete, Greece. Methods: Mean concentrations of particulate matter with an aerodynamic diameter of less than 2.5 µm (PM2.5) and less than 10 µm (PM10) during pregnancy were estimated at maternal home addresses with temporally adjusted land-use regression models. Levels of several inflammatory biomarkers were determined in child serum at 4 years of age via immunoassay. Exposure-outcome associations were assessed using log-binomial or Poisson regression with robust variances, in cases of non-convergence. Potential effect modification from maternal and offspring characteristics was examined by introducing interaction terms in multivariate models. Results: A 5 µg/m3 increase in concentration of PM2.5 and PM10 during pregnancy was associated with an increased risk of high levels (in the 5th quantile) of child interleukin-6 (IL-6) levels at 4 years (RR=2.68, 95%CI: 1.38, 5.20 and 1.28, 95%CI: 1.04, 1.57, respectively). Effects of prenatal exposure to both PM2.5 and PM10 remained significant only for non-smoking mothers in stratified analysis by maternal smoking status (p-interaction: 0.037 and 0.071, respectively). Child overweight/obesity (p-interaction: 0.013 and 0.001) and asthma status (p-interaction: 0.007 and 0.001) more than doubled the effects of maternal exposure to PM2.5 and PM10 on IL-6 at 4 years. Similar effects were found with other inflammatory biomarkers under study. Conclusions: Our results indicate alterations in systemic inflammatory markers in 4-y-old children in relation to prenatal exposure to traffic-related air pollution. Further work is needed to examine the underlying mechanisms and interactions between cytokines in the inflammatory response following air pollution exposure.

What is the health cost of haze pollution? Evidence from China.

Haze pollution has become a serious threat to the health of residents and has brought about considerable economic costs. The objectives of this study are to examine the relationship between haze pollution and residents' health and to estimate the health cost of haze pollution. Using macro data on 74 major Chinese cities, this study employs a static panel data model and a dynamic panel generalized method of moments model to investigate the impact of haze pollution on the mortality of residents. On the basis of the estimation results, the value of a statistical life (VOSL) method is used to evaluate the economic cost of haze pollution on residents' health. In 74 major cities of China, an increase in concentration of PM2.5 pollutants by 1μg/m3 may cause the mortality rate to rise by 25 per million people. The VOSL of haze pollution in China is about 1.53 million yuan. The health cost of residents from haze in 74 major cities of China in 2016 was about 888 billion yuan, equivalent to about 2% of the these cities' GDP. Haze pollution has serious damage to the health of urban residents and therefore brings about considerable economic losses.

Ambient air pollution and low birthweight: a European cohort study (ESCAPE)

Ambient air pollution has been associated with restricted fetal growth, which is linked with adverse respiratory health in childhood. We assessed the effect of maternal exposure to low concentrations of ambient air pollution on birthweight. We pooled data from 14 population-based mother-child cohort studies in 12 European countries. Overall, the study population included 74 178 women who had singleton deliveries between Feb 11, 1994, and June 2, 2011, and for whom information about infant birthweight, gestational age, and sex was available. The primary outcome of interest was low birthweight at term (weight <2500 g at birth after 37 weeks of gestation). Mean concentrations of particulate matter with an aerodynamic diameter of less than 2·5 μm (PM2·5), less than 10 μm (PM10), and between 2·5 μm and 10 μm during pregnancy were estimated at maternal home addresses with temporally adjusted land-use regression models, as was PM2·5 absorbance and concentrations of nitrogen dioxide (NO2) and nitrogen oxides. We also investigated traffic density on the nearest road and total traffic load. We calculated pooled effect estimates with random-effects models. A 5 μg/m(3) increase in concentration of PM2·5 during pregnancy was associated with an increased risk of low birthweight at term (adjusted odds ratio [OR] 1·18, 95% CI 1·06-1·33). An increased risk was also recorded for pregnancy concentrations lower than the present European Union annual PM2·5 limit of 25 μg/m(3) (OR for 5 μg/m(3) increase in participants exposed to concentrations of less than 20 μg/m(3) 1·41, 95% CI 1·20-1·65). PM10 (OR for 10 μg/m(3) increase 1·16, 95% CI 1·00-1·35), NO2 (OR for 10 μg/m(3) increase 1·09, 1·00-1·19), and traffic density on nearest street (OR for increase of 5000 vehicles per day 1·06, 1·01-1·11) were also associated with increased risk of low birthweight at term. The population attributable risk estimated for a reduction in PM2·5 concentration to 10 μg/m(3) during pregnancy corresponded to a decrease of 22% (95% CI 8-33%) in cases of low birthweight at term. Exposure to ambient air pollutants and traffic during pregnancy is associated with restricted fetal growth. A substantial proportion of cases of low birthweight at term could be prevented in Europe if urban air pollution was reduced. The European Union.