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The relationship between maternal exposure to air pollution during periods of pregnancy (entire and specific periods) and birth weight was investigated in a well-defined cohort. Between 1988 and 1991, all pregnant women living in four residential areas of Beijing were registered and followed from early pregnancy until delivery. Information on individual mothers and infants was collected. Daily air pollution data were obtained independently. The sample for analysis included 74,671 first-parity live births were gestational age 37-44 weeks. Multiple linear regression and logistic regression were used to estimate the effects of air pollution on birth weight and low birth weight (< 2,500 g), adjusting for gestational age, residence, year of birth, maternal age, and infant gender. There was a significant exposure-response relationship between maternal exposures to sulfur dioxide (SO2) and total suspended particles (TSP) during the third trimester of pregnancy and infant birth weight. The adjusted odds ratio for low birth weight was 1.11 (95% CI, 1.06-1.16) for each 100 micrograms/m3 increase in SO2 and 1.10 (95% CI, 1.05-1.14) for each 100 micrograms/m3 increase in TSP. The estimated reduction in birth weight was 7.3 g and 6.9 g for each 100 micrograms/m3 increase in SO2 and in TSP, respectively. The birth weight distribution of the high-exposure group was more skewed toward the left tail (i.e., with higher proportion of births < 2,500 g) than that of the low-exposure group. Although the effects of other unmeasured risk factors cannot be excluded with certainty, our data suggests that TSP and SO2, or a more complex pollution mixture associated with these pollutants, contribute to an excess risk of low birth weight in the Beijing population.

Background: Recent studies suggest that ambient air pollution exposure during pregnancy is associated with stillbirth occurrence. However, the results on the associations between ambient air pollutants and stillbirths are inconsistent and little is known about the gestational timing of sensitive periods for the effects of ambient air pollutants exposure on stillbirth.Objective: This study aimed to examine whether exposure to high levels of ambient air pollutants in a Chinese population is associated with an increased risk of stillbirth, and determine the gestational period when the fetus is most susceptible.Methods: We conducted a population-based cohort study in Wuhan, China, involving 95,354 births between June 10, 2011 and June 9, 2013. The exposure assessments were based on the daily mean concentrations of air pollutants obtained from the exposure monitor nearest to the pregnant women's residence. Logistic regression analyses were performed to determine the associations between stillbirths and exposure to each of the air pollutants at different pregnancy periods with adjustment for confounding factors.Results: Stillbirth increased with a 10 μg/m3 increase in particulate matter 2.5 (PM2.5) in each stage of pregnancy, and a significant association between carbon monoxide (CO) exposure and stillbirth was found during the third trimester (adjusted odds ratio (aOR): 1.01, 95% confidence interval (CI): 1.00-1.01) and in the entire pregnancy (aOR: 1.18, 95% CI: 1.04-1.34). Furthermore, an increased risk of stillbirth in the third trimester was associated with a 10 μg/m3 increase in PM10 (aOR: 1.08, 95% CI: 1.04-1.11), nitrogen dioxide (NO2) (aOR: 1.13, 95% CI: 1.07-1.21) and sulfur dioxide (SO2) (aOR: 1.26, 95% CI: 1.16-1.35). However, no positive association was observed between ozone exposure and stillbirth. In the two-pollutant models, PM2.5 and CO exposures were found to be consistently associated with stillbirth.Conclusions: Our study revealed that exposure to high levels of PM2.5, PM10, SO2, NO2 and CO increases the risk of stillbirth and the most susceptible gestational period to ambient air pollution exposure was in the third trimester. Further toxicological and prospective cohort studies with improved exposure assessments are needed to confirm the causal link between air pollutants and stillbirth. [ABSTRACT FROM AUTHOR]

Background: Existing studies exploring the association between low birth weight (LBW) and maternal fine particulate matter (aerodynamic diameter<2.5μm, PM2.5) exposure have presented equivocal results, and one of the possible reasons for this finding might be due to relatively low maternal exposures. In addition, relatively narrow maternal exposure windows to PM2.5 have not been well established for LBW.Methods: We employed a nested matched case-control design among 43,855 term births in a large maternity and child care hospital in Jinan, China. A total of 369 cases were identified, and four controls per case matched by maternal age were randomly selected among those with normal birth weight (n=1,476) from 2014 to 2016. Ambient air monitoring data on continuous measures of PM2.5, nitrogen dioxide (NO2), and sulfur dioxide (SO2) (24-h average concentrations) from 2013 to 2016 were collected from thirteen local monitoring stations. An inverse distance weighting method based on both home and work addresses was adopted to estimate the individual daily exposures to these air pollutants during pregnancy by weighting the average of the twelve nearest monitoring stations within 30km of each 100m×100m grid cell by an inverse squared distance, and then the average exposure concentrations for gestational months, trimesters and the entire pregnancy were calculated. Adjusted conditional logistic regression models were used to estimate the odds ratios (ORs) per 10μg/m3 increment in PM2.5 and by PM2.5 quartiles during different gestational periods.Results: In this study, the estimated mean values of PM2.5, NO2, and SO2 exposure during the entire pregnancy were 88.0, 54.6, and 63.1μg/m3, respectively. Term low birth weight (TLBW) increased in association with per 10μg/m3 increment in PM2.5 for the 8th month [OR=1.13, 95% confidence interval (CI): 1.04, 1.22], the 9th month (OR=1.06, 95% CI: 0.99, 1.15), the third trimester (OR=1.17, 95% CI: 1.05, 1.29), and the entire pregnancy (OR=1.38, 95% CI: 1.07, 1.77) in models adjusted for one pollutant (PM2.5). In models categorizing the PM2.5 exposure by quartiles, comparing the second, third, and highest with the lowest PM2.5 exposure quartile, the PM2.5 was positively associated with TLBW during the 8th month (OR: 1.77, 95% CI: 1.09, 2.88; OR: 1.77, 95% CI: 1.03, 3.04; OR: 1.92, 95% CI: 1.04, 3.55, respectively) and for the 9th month, only association for exposure in the third versus the lowest quartile was significant (OR: 1.91, 95% CI: 1.02, 3.58).Conclusions: The study provides evidence that exposure to PM2.5 during pregnancy might be associated with the risk of TLBW in the context of very high pollution level of PM2.5, and the 8th and 9th months were identified as potentially relevant exposure windows. [ABSTRACT FROM AUTHOR]

PM 2.5 is one of the most studied atmospheric pollutants due to its adverse impacts on human health and welfare and the environment. An improved model (the chemical mass balance gas constraint-Iteration: CMBGC-Iteration) is proposed and applied to identify source categories and estimate source contributions of PM 2.5. The CMBGC-Iteration model uses the ratio of gases to PM as constraints and considers the uncertainties of source profiles and receptor datasets, which is crucial information for source apportionment. To apply this model, samples of PM 2.5 were collected at Tianjin, a megacity in northern China. The ambient PM 2.5 dataset, source information, and gas-to-particle ratios (such as SO 2 /PM 2.5 , CO/PM 2.5 , and NOx/PM 2.5 ratios) were introduced into the CMBGC-Iteration to identify the potential sources and their contributions. Six source categories were identified by this model and the order based on their contributions to PM 2.5 was as follows: secondary sources (30%), crustal dust (25%), vehicle exhaust (16%), coal combustion (13%), SOC (7.6%), and cement dust (0.40%). In addition, the same dataset was also calculated by other receptor models (CMB, CMB-Iteration, CMB-GC, PMF, WALSPMF, and NCAPCA), and the results obtained were compared. Ensemble-average source impacts were calculated based on the seven source apportionment results: contributions of secondary sources (28%), crustal dust (20%), coal combustion (18%), vehicle exhaust (17%), SOC (11%), and cement dust (1.3%). The similar results of CMBGC-Iteration and ensemble method indicated that CMBGC-Iteration can produce relatively appropriate results. [ABSTRACT FROM AUTHOR]

A campaign was conducted to assess and compare the personal exposure in L3 of Tianjin subway, focusing on PM levels, chemical compositions, morphology analysis, as well as the health risk of heavy metal in PM. The results indicated that the average concentration of the PM was 151.43 μg/m inside the train of the subway during rush hours. PM concentrations inside car under the ground are higher than those on the ground, and PM concentrations on the platform are higher than those inside car. Regarding metal concentrations, the highest element in PM samples was Fe; the level of which is 17.55 μg/m. OC is a major component of PM in Tianjin subway. Secondary organic carbon is the formation of gaseous organic pollutants in subway. SEM-EDX and TEM-EDX exhibit the presence of individual particle with a large metal content in the subway samples. For small Fe metal particles, iron oxide can be formed easily. With regard to their sources, Fe-containing particles are generated mainly from mechanical wear and friction processes at the rail-wheel-brake interfaces. The non-carcinogenic risk to metals Cr, Ni, Cu, Zn and Pb, and carcinogenic hazard of Cr and Ni were all below the acceptable level in L3 of Tianjin subway. [ABSTRACT FROM AUTHOR]

The Asian continental dust storms, originated mainly from the deserts bordering China and Mongolia, increasingly influenced the air quality of Taiwan between February and May in recent years. The concentrations of both coarse (PM10) and fine (PM2.5) particles increased in northern Taiwan during the dust storm periods. The potential health impact of the dust storms was worried by the people but not investigated before. The purpose of this study is to estimate adverse health effects of the Asian continental dust storms among susceptible Taipei residents in 2002.We investigated associations between dust storms and hemostatic factors for 14 patients with coronary heart disease (CHD) and 7 patients without CHD in Taipei during the dust storm period in 2002. Baseline measurements including hemostatic factors (tissue plasminogen activator (tPA), plasminogen activator inhibitor-1 (PAI-1), fibrinogen, Ddimer), and inflammatory markers (high sensitive C reactive protein (hs-CRP) and interleukin-6) are measured before dust storms reach Taiwan. Air pollution data including PM10, PM2.5, O3; SO2, NO2, and CO are obtained from 5 monitoring stations in Taiwan. During the dust storm period from March to May in 2002, we recall all study subjects and perform hemostatic measurements on them.The concentrations of PM10, PM2.5, and O3 increased significantly during the dust storm period. We find plasma tPA increase significantly in both groups. PAI-1 shows slightly but not significantly decrease in the CHD group. There is no significant change in inflammatory marker of interleukin-6. Compared with non-CHD group.Long-range transported pollution of Asian continental dust storm elevated environmental concentrations of PM10, PM2.5, and O3 in Taipei. The elevated pollution results in increase in plasma tPA levels among susceptible patients in Taipei. [ABSTRACT FROM AUTHOR]