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Gestational hypertension and preeclampsia are the most common complications of pregnancy affecting 2% to 10% of pregnancies after 20 weeks of pregnancy. 6,7 Gestational hypertension is usually diagnosed based on a systolic blood pressure of ≥140 mm Hg or a diastolic blood pressure of ≥90 mm Hg in previously normotensive women. 7 Preeclampsia is characterized by hypertension and protein in the urine. 6,8 In addition to maternal mortality, preeclampsia and related conditions are a leading cause of maternal morbidity, perinatal death, placental abruption, preterm birth, and child growth restriction. [6][7][8] The objective of this study was to systematically review epidemiological studies investigating associations between ambient air pollution and pregnancy-induced hypertensive disorders and to perform a meta-analysis of these studies.Abstract-Pregnancy-induced hypertensive disorders can lead to maternal and perinatal morbidity and mortality, but the cause of these conditions is not well understood. We have systematically reviewed and performed a meta-analysis of epidemiological studies investigating the association between exposure to ambient air pollution and pregnancy-induced hypertensive disorders including gestational hypertension and preeclampsia. We searched electronic databases for English language studies reporting associations between ambient air pollution and pregnancy-induced hypertensive disorders published between December 2009 and December 2013. Combined risk estimates were calculated using random-effect models for each exposure that had been examined in ≥4 studies. Heterogeneity and publication bias were evaluated. A total of 17 articles evaluating the impact of nitrogen oxides (NO 2 , NO X ), particulate matter (PM 10 , PM 2.5 ), carbon monoxide (CO), ozone (O 3 ), proximity to major roads, and traffic density met our inclusion criteria. Most studies reported that air pollution increased risk for pregnancy-induced hypertensive disorders. There was significant heterogeneity in meta-analysis, which included 16 studies reporting on gestational hypertension and preeclampsia as separate or combined outcomes; there was less heterogeneity in findings of the 10 studies reporting solely on preeclampsia. Metaanalyses showed increased risks of hypertensive disorders in pregnancy for all pollutants except CO. Random-effect meta-analysis combined odds ratio associated with a 5-µg/m 3 increase in PM 2.5 was 1.57 (95% confidence interval, 1.26-1.96) for combined pregnancy-induced hypertensive disorders and 1.31 (95% confidence interval, 1.14-1.50) for preeclampsia. Our results suggest that exposure to air pollution increases the risk of pregnancy-induced hypertensive (Figure 1). A total of 17 studies were considered relevant to be included in the systematic review and meta-analysis. If not reported, we requested from the authors effect estimates for continuous exposure. Additional unpublished information was received for a Swedish study, 9 which was included in our analyses. We excluded 1 small (n=2707) stu...

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Background:Epidemiological evidence on the association between ambient air pollution and breast cancer risk is inconsistent.Objective:We examined the association between long-term exposure to ambient air pollution and incidence of postmenopausal breast cancer in European women.Methods:In 15 cohorts from nine European countries, individual estimates of air pollution levels at the residence were estimated by standardized land-use regression models developed within the European Study of Cohorts for Air Pollution Effects (ESCAPE) and Transport related Air Pollution and Health impacts - Integrated Methodologies for Assessing Particulate Matter (TRANSPHORM) projects: particulate matter (PM) ≤2.5μm, ≤10μm, and 2.5–10μm in diameter (PM2.5, PM10, and PMcoarse, respectively); PM2.5 absorbance; nitrogen oxides (NO2 and NOnormalx); traffic intensity; and elemental composition of PM. We estimated cohort-specific associations between breast cancer and air pollutants using Cox regression models, adjusting for major lifestyle risk factors, and pooled cohort-specific estimates using random-effects meta-analyses.Results:Of 74,750 postmenopausal women included in the study, 3,612 developed breast cancer during 991,353 person-years of follow-up. We found positive and statistically insignificant associations between breast cancer and PM2.5 {hazard ratio (HR)=1.08 [95% confidence interval (CI): 0.77, 1.51] per 5 μg/m3}, PM10 [1.07 (95% CI: 0.89, 1.30) per 10 μg/m3], PMcoarse [1.20 (95% CI: 0.96, 1.49 per 5 μg/m3], and NO2 [1.02 (95% CI: 0.98, 1.07 per 10 μg/m3], and a statistically significant association with NOnormalx [1.04 (95% CI: 1.00, 1.08) per 20 μg/m3, p=0.04].Conclusions:We found suggestive evidence of an association between ambient air pollution and incidence of postmenopausal breast cancer in European women. https://doi.org/10.1289/EHP1742