A cohort study of traffic-related air pollution impacts on birth outcomes

Ambient air pollutant PM10 and risk of preterm birth in Lanzhou, China

IMPORTANCE

Exposure to ambient particulate matter during pregnancy has been suggested as a risk factor for preterm birth. However results from limited epidemiologic studies have been inconclusive. Very few studies have been conducted in areas with high air pollution levels.

OBJECTIVE

We investigated the hypothesis that high level exposure to particulate matter with aerodynamic diameter no larger than 10μm (PM10) during pregnancy increases the risk of preterm birth.

METHODS

A birth cohort study was carried out between 2010 and 2012 in Lanzhou, China, including 8969 singleton live births with available information on daily PM10 levels from four monitoring stations, individual exposures during pregnancy were calculated using inverse-distance weighting based on both home and work addresses. Unconditional logistic regression modeling was used to examine the associations between PM10 exposure and risk of preterm birth and its clinical subtypes.

RESULTS

Increased risk of very preterm birth was associated with exposure to PM10 during the last two months of pregnancy (OR, 1.07; 95%CI, 1.02-1.13 per 10μg/m(3) increase for last four weeks before delivery; 1.09; 1.02-1.15 for last six weeks before delivery; 1.10; 1.03-1.17 for last eight weeks before delivery). Compared to the U.S. National Ambient Air Quality Standard (150μg/m(3)), higher exposure level (≥150μg/m(3)) of PM10 during entire pregnancy was associated with an increased risk of preterm birth (1.48; 1.22-1.81) and the association was higher for medically indicated preterm birth (1.80, 1.24-2.62) during entire pregnancy and for very preterm during last 6weeks before delivery (2.03, 1.11-3.72).

CONCLUSIONS AND RELEVANCE

Our study supports the hypothesis that exposure to high levels of ambient PM10 increases the risk of preterm birth. Our study also suggests that the risk may vary by clinical subtypes of preterm birth and exposure time windows. Our findings are relevant for health policy makers from China and other regions with high levels of air pollution to facilitate the efforts of reducing air pollution level in order to protect public health.

Maternal exposure to fine particulate matter (PM2.5) and pregnancy outcomes: a meta-analysis

A growing body of evidence has investigated the association between maternal exposure to PM2.5 (particulate matter with aerodynamic diameter 2.5 μm) during pregnancy and adverse pregnancy outcomes. However, the results of those studies are not consistent. To synthetically quantify the relationship between maternal exposure to PM2.5 during pregnancy and pregnancy outcomes (the change in birth weight, low birth weight (LBW), preterm birth (PTB), small for gestational age (SGA), and stillbirth), a meta-analysis of 25 published observational epidemiological studies that met our selection criteria was conducted. Results suggested a 10 μg/m(3) increase in PM2.5 was positively associated with LBW (odds ratio (OR) = 1.05; 95 % confidence interval (CI), 1.02-1.07), PTB (OR = 1.10; 95 % CI, 1.03-1.18), and SGA (OR = 1.15; 95 % CI, 1.10-1.20) based on entire pregnancy exposure, and pooled estimate of decrease in birth weight was 14.58 g (95 % CI, 9.86-19.31); however, there was no evidence of a statistically significant effect of per 10 μg/m(3) increase in PM2.5 exposure on the risk of stillbirth (OR = 1.18; 95 % CI, 0.69-2.04). With respect to three different gestation periods, no significant risks were found in PTB, stillbirth, and the first trimester on the change of birth weight with a 10 μg/m(3) increase in PM2.5. In this study, a comprehensive quantitative analysis of the results show that PM2.5 can increase the risk of LBW, PTB, and SGA; pregnant women need to take effective measures to reduce PM2.5 exposure.

Residential proximity to major roads and term low birth weight: the roles of air pollution, heat, noise, and road-adjacent trees

BACKGROUND

Maternal residential proximity to roads has been associated with adverse pregnancy outcomes. However, there is no study investigating mediators or buffering effects of road-adjacent trees on this association. We investigated the association between mothers' residential proximity to major roads and term low birth weight (LBW), while exploring possible mediating roles of air pollution (PM(2.5), PM(2.5-10), PM(10), PM(2.5) absorbance, nitrogen dioxide, and nitrogen oxides), heat, and noise and buffering effect of road-adjacent trees on this association.

METHODS

This cohort study was based on 6438 singleton term births in Barcelona, Spain (2001-2005). Road proximity was measured as both continuous distance to and living within 200 m from a major road. We assessed individual exposures to air pollution, noise, and heat using, respectively, temporally adjusted land-use regression models, annual averages of 24-hour noise levels across 50 m and 250 m, and average of satellite-derived land-surface temperature in a 50-m buffer around each residential address. We used vegetation continuous fields to abstract tree coverage in a 200-m buffer around major roads.

RESULTS

Living within 200 m of major roads was associated with a 46% increase in term LBW risk; an interquartile range increase in heat exposure with an 18% increase; and third-trimester exposure to PM(2.5), PM(2.5-10), and PM10 with 24%, 25%, and 26% increases, respectively. Air pollution and heat exposures together explained about one-third of the association between residential proximity to major roads and term LBW. Our observations on the buffering of this association by road-adjacent trees were not consistent between our 2 measures of proximity to major roads.

CONCLUSION

An increased risk of term LBW associated with proximity to major roads was partly mediated by air pollution and heat exposures.

Integrating smart-phone based momentary location tracking with fixed site air quality monitoring for personal exposure assessment

Epidemiological studies investigating relationships between environmental exposures from air pollution and health typically use residential addresses as a single point for exposure, while environmental exposures in transit, at work, school or other locations are largely ignored. Personal exposure monitors measure individuals' exposures over time; however, current personal monitors are intrusive and cannot be operated at a large scale over an extended period of time (e.g., for a continuous three months) and can be very costly. In addition, spatial locations typically cannot be identified when only personal monitors are used. In this paper, we piloted a study that applied momentary location tracking services supplied by smart phones to identify an individual's location in space-time for three consecutive months (April 28 to July 28, 2013) using available Wi-Fi networks. Individual exposures in space-time to the traffic-related pollutants Nitrogen Oxides (NOX) were estimated by superimposing an annual mean NOX concentration surface modeled using the Land Use Regression (LUR) modeling technique. Individual's exposures were assigned to stationary (including home, work and other stationary locations) and in-transit (including commute and other travel) locations. For the individual, whose home/work addresses were known and the commute route was fixed, it was found that 95.3% of the time, the individual could be accurately identified in space-time. The ambient concentration estimated at the home location was 21.01 ppb. When indoor/outdoor infiltration, indoor sources of air pollution and time spent outdoors were taken into consideration, the individual's cumulative exposures were 28.59 ppb and 96.49 ppb, assuming a respective indoor/outdoor ratio of 1.33 and 5.00. Integrating momentary location tracking services with fixed-site field monitoring, plus indoor-outdoor air exchange calibration, makes exposure assessment of a very large population over an extended time period feasible.

Relationship between exposure to fine particulates and ozone and reduced lung function in children

BACKGROUND

A limited number of studies have reported an association between long-term exposure to ambient air pollutants and lung function growth among children, with inconclusive results.

OBJECTIVES

To assess the relationship between air pollutant exposure and lung function growth, and to examine potential sex differences in the susceptibility of lung function growth to air pollution.

METHODS

We conducted a two-year prospective cohort study of Taiwanese children aged 12 at baseline who were followed from October 1, 2007 to November 31, 2009. The study population comprised 2941 non-smoking children who completed pulmonary function tests at both baseline and follow-up surveys. We applied spatial modeling for individual-level exposure assessment to capture relevant exposures and also attempted to eliminate potential community-level confounding. The exposure parameters were annual averages and values calculated from 24-hourly PM2.5 and 8-hourly ozone (O3) concentrations, corresponding to the residential addresses over the study period. The effect estimates were presented as lung function growth deficits per interquartile range (IQR) for PM2.5 and O3.

RESULTS

In a multiple linear mixed effect model, adjusted for confounding, growth deficits in the forced vital capacity (FVC), forced expiration volume in 1s (FEV1), and forced expiratory flow between the 25th and 75th percentiles of the FVC were associated with increased exposure to PM2.5 and O3. For example, greater exposure to PM2.5 (IQR, 17.92μg/m(3)) was associated with an annual deficit in FVC growth of 75mL in boys and 61mL in girls (p for interaction <0.05). Similar associations were found for O3.

CONCLUSIONS

The study provides evidence that long-term exposure to PM2.5 and O3 may have a detrimental effect on the development of lung function in children. The estimated deficits were generally larger in boys, compared to girls.

Commentary: Flawed scientific-evidence standards delay diesel regulations

Of 188 government-monitored air toxics, diesel particulate matter (DPM) causes seven times more cancer than all the other 187 air toxics combined, including benzene, lead, and mercury. Yet, DPM is the only air toxic not regulated more stringently under the Clean Air Act, as a hazardous air pollutant (HAP). One reason is that regulators use flawed standards of scientific evidence. The article argues (1) that DPM meets all six specified evidentiary criteria, any one of which is sufficient for HAP regulation and (2) that regulators' standards of evidence for denying HAP status to DPM (no DPM unit-risk estimate, inadequate dose-response data, alleged weak mechanistic data) err logically and scientifically, set the evidence bar too high, delay regulation, and allow 21,000 avoidable DPM deaths annually in the U.S.

Relationships between mild PM10 and ozone urban air levels and spontaneous abortion: clues for primary prevention

The effects of environmental pollution on spontaneous abortion (SAB) are still unclear. Records of SAB were collected from five cities (514,996 residents) and correlated with PM10, NO(2) and ozone levels. Median pollutant concentrations were below legal limits. Monthly SABs positively correlated with PM10 and ozone levels but not with NO(2) levels. The mean monthly SAB rate increase was estimated equal to 19.7 and 33.6 % per 10 μg/m(3) increase in PM10 or ozone concentration, respectively. Higher values of PM10 and SABs were evident in cities with- than in those without pollutant industries, with a number of SABs twofolds higher in the former group. In conclusion, SAB occurrence is affected by PM10 (particularly if industrial areas are present) and ozone concentrations, also at levels below the legal limits. Thus, SAB might be considered, at least in part, a preventable condition.

Outdoor air pollution and term low birth weight in Japan

INTRODUCTION

Evidence has accumulated on the association between ambient air pollution and adverse birth outcomes. However, most of the previous studies were conducted in geographically distinct areas and suffer from lack of important potential covariates. We examined the effect of ambient air pollution on term low birth weight (LBW) using data from a nationwide population-based longitudinal survey in Japan that began in 2001.

METHODS

We restricted participants to term singletons (n=44,109). Air pollution concentrations during the 9months before birth were obtained at the municipality level and were assigned to the participants who were born in the corresponding municipality. We conducted multilevel logistic regression analyses adjusting for individual and municipality-level variables.

RESULTS

We found that air pollution exposure during pregnancy was positively associated with the risk of term LBW. In the fully adjusted models, odds ratios following one interquartile range increase in each pollutant were 1.09 (95% confidence interval: 1.00, 1.19) for suspended particulate matter (SPM), 1.11 (0.99, 1.26) for nitrogen dioxide (NO2), and 1.71 (1.18, 2.46) for sulfur dioxide (SO2). Specifically, effect estimates for SPM and NO2 exposure at the first trimester were higher than those at other trimesters, while SO2 was associated with the risk at all trimesters. Nonsmoking mothers were more susceptible to SPM and NO2 exposure compared with smoking mothers.

CONCLUSIONS

Ambient air pollution increases the risk of term LBW in a nationally representative sample in Japan.

Smog and socioeconomics: an evaluation of equity in traffic-related air pollution generation and exposure

How traffic-related air pollution generation and exposure is distributed among different population groups is an important environmental justice concern. From a social equity perspective, many questions arise at the metropolitan scale. Do socially disadvantaged communities have higher exposure levels to traffic-related air pollution? Do discrepancies exist wherein neighborhoods are not exposed to levels of pollution similar to those they themselves generate? And, is there a relationship between this discrepancy and social disadvantage? These questions are examined for the Montreal Metropolitan Region through the development of an integrated transport and emissions model. Two measures of traffic-related air pollution are estimated at the traffic analysis zone level: (1) generation (average emissions per household), and (2) exposure (average residential zone concentration). A social disadvantage index is also calculated that incorporates elements of social and material deprivation. Three levels of inequity exist regarding emissions, exposure, and socioeconomics. Social disadvantage was found to have a positive relationship with exposure, meaning that the most socially disadvantaged communities tend to experience the highest levels of traffic-related air pollution. Spatial discrepancies in emission generation versus emission exposure are also present for most of the metropolitan region. Furthermore, the communities that face a double burden of greater disadvantage and higher exposure also tend to create the lowest quantities of pollution.

A meta-analysis of exposure to particulate matter and adverse birth outcomes

OBJECTIVES

The objective of this study was to conduct a systematic review to provide summarized evidence on the association between maternal exposure to particulate air pollution and birth weight (BW) and preterm birth (PTB) after taking into consideration the potential confounding effect of maternal smoking.

METHODS

We systematically searched all published cohort and case-control studies examining BW and PTB association with particulate matter (PM, less than or equal to 2.5μm and 10.0 μm in diameter, PM2.5 and PM10, respectively) from PubMed and Web of Science, from January 1980 to April 2015. We extracted coefficients for continuous BW and odds ratio (OR) for PTB from each individual study, and meta-analysis was used to combine the coefficient and OR of individual studies. The methodological quality of individual study was assessed using a standard protocol proposed by Downs and Black. Forty-four studies met the inclusion criteria.

RESULTS

In random effects meta-analyses, BW as a continuous outcome was negativelyassociated with 10 μg/m(3) increase in PM10 (-10.31 g; 95% confidence interval [CI], -13.57 to -3.13 g; I-squared=0%, p=0.947) and PM2.5 (-22.17 g; 95% CI, -37.93 to -6.41 g; I-squared=92.3%, p <0.001) exposure during entire pregnancy, adjusted for maternal smoking. A significantly increased risk of PTB per 10 μg/m(3) increase in PM10 (OR, 1.23; 95% CI, 1.04 to 1.41; I-squared=0%, p =0.977) and PM2.5 (OR, 1.14; 95% CI, 1.06 to 1.22; I-squared=92.5%, p <0.001) exposure during entire pregnancy was observed. Effect size of change in BW per 10 μg/m(3) increase in PM tended to report stronger associations after adjustment for maternal smoking.

CONCLUSIONS

While this systematic review supports an adverse impact of maternal exposure to particulate air pollution on birth outcomes, variation in effects by exposure period and sources of heterogeneity between studies should be further explored.

Heck J, Malagoli C, Del Giovane C, Vinceti M. A review and meta-analysis of outdoor air pollution and risk of childhood leukemia

Leukemia is the most frequent malignant disease affecting children. To date, the etiology of childhood leukemia remains largely unknown. Few risk factors (genetic susceptibility, infections, ionizing radiation, etc.) have been clearly identified, but they appear to explain only a small proportion of cases. Considerably more uncertain is the role of other environmental risk factors, such as indoor and outdoor air pollution. We sought to summarize and quantify the association between traffic-related air pollution and risk of childhood leukemia, and further examined results according to method of exposure assessment, study quality, leukemia subtype, time period, and continent where studies took place. After a literature search yielded 6 ecologic and 20 case-control studies, we scored the studies based on the Newcastle-Ottawa Scale. The studies assessed residential exposure to pollutants from motorized traffic by computing traffic density in the neighboring roads or vicinity to petrol stations, or by using measured or modeled nitrogen dioxide and benzene outdoor air levels. Because heterogeneity across studies was observed, random-effects summary odds ratios (OR) and 95% confidence intervals (CI) were reported. Whenever possible we additionally conducted stratified analyses comparing acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). Limiting the analysis to high-quality studies (Newcastle-Ottawa Scale ≥ 7), those using traffic density as the exposure assessment metric showed an increase in childhood leukemia risk in the highest exposure category (OR = 1.07, 95% CI 0.93-1.24). However, we observed evidence of publication bias. Results for NO2 exposure and benzene showed an OR of 1.21 (95% CI 0.97-1.52) and 1.64 (95% CI 0.91-2.95) respectively. When stratifying by leukemia type, the results based upon NO2 were 1.21 (95% CI 1.04-1.41) for ALL and 1.06 (95% CI 0.51-2.21) for AML; based upon benzene were 1.09 (95% CI 0.67-1.77) for ALL and 2.28 (95% CI 1.09-4.75) for AML. Estimates were generally higher for exposures in the postnatal period compared to the prenatal period, and for European studies compared to North American studies. Overall, our results support a link between ambient exposure to traffic pollution and childhood leukemia risk, particularly due to benzene.

Impacts of travel activity and urbanicity on exposures to ambient oxides of nitrogen and on exposure disparities

Daily exposures to ambient oxides of nitrogen were estimated here for residents of Hillsborough County, FL. The 2009 National Household Travel Survey provided geocoded data on fixed activity locations during each person-day sampled. Routes between activity locations were calculated from transportation network data, assuming the quickest travel path. To estimate daily exposure concentrations for each person-day, the exposure locations were matched with diurnally and spatially varying ambient pollutant concentrations derived from CALPUFF dispersion model results. The social distribution of exposures was analyzed by comparing frequency distributions of grouped daily exposure concentrations and by regression modeling. To investigate exposure error, the activity-based exposure estimates were also compared with estimates derived using residence location alone. The mean daily activity-based exposure concentration for the study sample was 17 μg/m³, with values for individual person-day records ranging from 7.0 to 43 μg/m³. The highest mean exposure concentrations were found for the following groups: black (20 μg/m³), below poverty (18 μg/m³), and urban residence location (22 μg/m³). Urban versus rural residence was associated with the largest increase in exposure concentration in the regression (8.3 μg/m³). Time in nonresidential activities, including travel, was associated with an increase of 0.2 μg/m³ per hour. Time spent travelling and at nonresidential locations contributed an average of 6 and 24 %, respectively, to the daily estimate. A mean error of 3.6 %, with range from -64 to 58 %, was found to result from using residence location alone. Exposure error was highest for those who travel most, but lowest for the sociodemographic subgroups with higher mean exposure concentrations (including blacks and those from below poverty households). This work indicates the importance of urbanicity to social disparities in activity-based air pollution exposures. It also suggests that exposure error due to using residence location may be smaller for more exposed groups.

Comparing land use regression and dispersion modelling to assess residential exposure to ambient air pollution for epidemiological studies

BACKGROUND

Land-use regression (LUR) and dispersion models (DM) are commonly used for estimating individual air pollution exposure in population studies. Few comparisons have however been made of the performance of these methods.

OBJECTIVES

Within the European Study of Cohorts for Air Pollution Effects (ESCAPE) we explored the differences between LUR and DM estimates for NO2, PM10 and PM2.5.

METHODS

The ESCAPE study developed LUR models for outdoor air pollution levels based on a harmonised monitoring campaign. In thirteen ESCAPE study areas we further applied dispersion models. We compared LUR and DM estimates at the residential addresses of participants in 13 cohorts for NO2; 7 for PM10 and 4 for PM2.5. Additionally, we compared the DM estimates with measured concentrations at the 20-40 ESCAPE monitoring sites in each area.

RESULTS

The median Pearson R (range) correlation coefficients between LUR and DM estimates for the annual average concentrations of NO2, PM10 and PM2.5 were 0.75 (0.19-0.89), 0.39 (0.23-0.66) and 0.29 (0.22-0.81) for 112,971 (13 study areas), 69,591 (7) and 28,519 (4) addresses respectively. The median Pearson R correlation coefficients (range) between DM estimates and ESCAPE measurements were of 0.74 (0.09-0.86) for NO2; 0.58 (0.36-0.88) for PM10 and 0.58 (0.39-0.66) for PM2.5.

CONCLUSIONS

LUR and dispersion model estimates correlated on average well for NO2 but only moderately for PM10 and PM2.5, with large variability across areas. DM predicted a moderate to large proportion of the measured variation for NO2 but less for PM10 and PM2.5.

The shared pathoetiological effects of particulate air pollution and the social environment on fetal-placental development

Exposure to particulate air pollution and socioeconomic risk factors are shown to be independently associated with adverse pregnancy outcomes; however, their confounding relationship is an epidemiological challenge that requires understanding of their shared etiologic pathways affecting fetal-placental development. The purpose of this paper is to explore the etiological mechanisms associated with exposure to particulate air pollution in contributing to adverse pregnancy outcomes and how these mechanisms intersect with those related to socioeconomic status. Here we review the role of oxidative stress, inflammation and endocrine modification in the pathoetiology of deficient deep placentation and detail how the physical and social environments can act alone and collectively to mediate the established pathology linked to a spectrum of adverse pregnancy outcomes. We review the experimental and epidemiological literature showing that diet/nutrition, smoking, and psychosocial stress share similar pathways with that of particulate air pollution exposure to potentially exasperate the negative effects of either insult alone. Therefore, socially patterned risk factors often treated as nuisance parameters should be explored as potential effect modifiers that may operate at multiple levels of social geography. The degree to which deleterious exposures can be ameliorated or exacerbated via community-level social and environmental characteristics needs further exploration.

Ambient Air Pollution and Hypertensive Disorders of Pregnancy: A Systematic Review and Meta-analysis

Hypertensive disorders of pregnancy (HDP, including gestational hypertension, preeclampsia, and eclampsia) have a substantial public health impact. Maternal exposure to high levels of air pollution may trigger HDP, but this association remains unclear. The objective of our report is to assess and quantify the association between maternal exposures to criteria air pollutants (ozone, carbon monoxide, nitrogen dioxide, sulfur dioxide, and particulate matter ≤ 10, 2.5 μm) on HDP risk. PubMed, EMBASE, MEDLINE, Current Contents, Global Health, and Cochrane were searched (last search: September, 2013). After a detailed screening of 270 studies, 10 studies were extracted. We conducted meta-analyses if a pollutant in a specific exposure window was reported by at least four studies. Using fixed- and random-effects models, odds ratios (ORs) and 95% CIs were calculated for each pollutant with specific increment of concentration. Increases in risks of HDP (OR per 10 ppb = 1.16; 95% CI, 1.03-1.30) and preeclampsia (OR per 10 ppb = 1.10; 95% CI, 1.03-1.17) were observed to be associated with exposure to NO2 during the entire pregnancy, and significant associations between HDP and exposure to CO (OR per 1 ppm = 1.79; 95% CI, 1.31-2.45) and O3 (OR per 10 ppb = 1.09; 95% CI, 1.05-1.13) during the first trimester were also observed. Our review suggests an association between ambient air pollution and HDP risk. Although the ORs were relatively low, the population-attributable fractions were not negligible given the ubiquitous nature of air pollution.

Proximity to traffic, ambient air pollution, and community noise in relation to incident rheumatoid arthritis

BACKGROUND

The risk of rheumatoid arthritis (RA) has been associated with living near traffic; however, there is evidence suggesting that air pollution may not be responsible for this association. Noise, another traffic-generated exposure, has not been studied as a risk factor for RA.

OBJECTIVES

We investigated proximity to traffic, ambient air pollution, and community noise in relation to RA in the Vancouver and Victoria regions of British Columbia, Canada.

METHODS

Cases and controls were identified in a cohort of adults that was assembled using health insurance registration records. Incident RA cases from 1999 through 2002 were identified by diagnostic codes in combination with prescriptions and type of physician (e.g., rheumatologist). Controls were matched to RA cases by age and sex. Environmental exposures were assigned to each member of the study population by their residential postal code(s). We estimated relative risks using conditional logistic regression, with additional adjustment for median income at the postal code.

RESULTS

RA incidence was increased with proximity to traffic, with an odds ratio (OR) of 1.37 (95% CI: 1.11, 1.68) for residence ≤ 50 m from a highway compared with residence > 150 m away. We found no association with traffic-related exposures such as PM2.5, nitrogen oxides, or noise. Ground-level ozone, which was highest in suburban areas, was associated with an increased risk of RA (OR = 1.26; 95% CI: 1.18, 1.36 per interquartile range increase).

CONCLUSIONS

Our study confirms a previously observed association of RA risk with proximity to traffic and suggests that neither noise levels nor traffic-related air pollutants are responsible for this relationship. Additional investigation of neighborhood and individual correlates of residence near roadways may provide new insight into risk factors for RA.

Maternal exposure to fine particulate pollution during narrow gestational periods and newborn health in Harris County, Texas

It remains unclear when the fetus is most susceptible to the effects of particulate air pollution. We conducted a population-based study in a large urban area to evaluate associations between preterm birth (PTB) and fetal growth and exposures to fine particles (PM(2.5)) during narrow periods of gestation. We identified 177,816 births during 2005-2007 among mothers who resided in Harris County, Texas at the time of delivery. We created three mutually exclusive categories of mildly (33-36 completed weeks of gestation), moderately (29-32 weeks of gestation), and severely (20-28 weeks of gestation) PTB, and among full term infants, we identified those who were born small for their gestational age. Using routine air monitoring data, we generated county-level daily time series of estimated ambient air levels of PM2.5 and then computed exposure metrics during every 4 weeks of a mother's pregnancy. We evaluated associations in each 4-week period using multiple logistic regression. A 10 μg/m(3) increase in PM(2.5) exposure in the first 4 weeks of pregnancy significantly increased the odds of mildly, moderately and severely PTB by 16, 71 and 73 %, respectively. Associations were stronger when infants with birth defects were excluded. Our findings indicate an association between PM(2.5) and PTB, with stronger associations for moderately and severely PTB infants. Efforts should continue to implement stricter air quality standards and improve ambient air quality.

Sources and contents of air pollution affecting term low birth weight in Los Angeles County, California, 2001-2008

BACKGROUND

Low birth weight (LBW, <2500 g) has been associated with exposure to air pollution, but it is still unclear which sources or components of air pollution might be in play. The association between ultrafine particles and LBW has never been studied.

OBJECTIVES

To study the relationships between LBW in term born infants and exposure to particles by size fraction, source and chemical composition, and complementary components of air pollution in Los Angeles County (California, USA) over the period 2001-2008.

METHODS

Birth certificates (n=960,945) were geocoded to maternal residence. Primary particulate matter (PM) concentrations by source and composition were modeled. Measured fine PM, nitrogen dioxide and ozone concentrations were interpolated using empirical Bayesian kriging. Traffic indices were estimated. Associations between LBW and air pollution metrics were examined using generalized additive models, adjusting for maternal age, parity, race/ethnicity, education, neighborhood income, gestational age and infant sex.

RESULTS

Increased LBW risks were associated with the mass of primary fine and ultrafine PM, with several major sources (especially gasoline, wood burning and commercial meat cooking) of primary PM, and chemical species in primary PM (elemental and organic carbon, potassium, iron, chromium, nickel, and titanium but not lead or arsenic). Increased LBW risks were also associated with total fine PM mass, nitrogen dioxide and local traffic indices (especially within 50 m from home), but not with ozone. Stronger associations were observed in infants born to women with low socioeconomic status, chronic hypertension, diabetes and a high body mass index.

CONCLUSIONS

This study supports previously reported associations between traffic-related pollutants and LBW and suggests other pollution sources and components, including ultrafine particles, as possible risk factors.

Sources of fine particulate matter and risk of preterm birth in Connecticut, 2000-2006: a longitudinal study

BACKGROUND

Previous studies have examined fine particulate matter (≤ 2.5 μm; PM2.5) and preterm birth, but there is a dearth of longitudinal studies on this topic and a paucity of studies that have investigated specific sources of this exposure.

OBJECTIVES

Our aim was to assess whether anthropogenic sources are associated with risk of preterm birth, comparing successive pregnancies to the same woman.

METHODS

Birth certificates were used to select women who had vaginal singleton live births at least twice in Connecticut during 2000-2006 (n = 23,123 women, n = 48,208 births). We procured 4,085 daily samples of PM2.5 on Teflon filters from the Connecticut Department of Environmental Protection for six cities in Connecticut. Filters were analyzed for chemical composition, and Positive Matrix Factorization was used to determine contributions of PM2.5 sources. Risk estimates were calculated with conditional logistic regression, matching pregnancies to the same women.

RESULTS

Odds ratios of preterm birth per interquartile range increase in whole pregnancy exposure to dust, motor vehicle emissions, oil combustion, and regional sulfur PM2.5 sources were 1.01 (95% CI: 0.93, 1.09), 1.01 (95% CI: 0.92, 1.10), 1.00 (95% CI: 0.89, 1.12), and 1.09 (95% CI: 0.97, 1.22), respectively.

CONCLUSION

This was the first study of PM2.5 sources and preterm birth, and the first matched analysis, that better addresses individual-level confounding potentially inherent in all past studies. There was insufficient evidence to suggest that sources were statistically significantly associated with preterm birth. However, elevated central estimates and previously observed associations with mass concentration motivate the need for further research. Future studies would benefit from high source exposure settings and longitudinal study designs, such as that adopted in this study.

Residential greenness and birth outcomes: evaluating the influence of spatially correlated built-environment factors

BACKGROUND

Half the world's population lives in urban areas. It is therefore important to identify characteristics of the built environment that are beneficial to human health. Urban greenness has been associated with improvements in a diverse range of health conditions, including birth outcomes; however, few studies have attempted to distinguish potential effects of greenness from those of other spatially correlated exposures related to the built environment.

OBJECTIVES

We aimed to investigate associations between residential greenness and birth outcomes and evaluate the influence of spatially correlated built environment factors on these associations.

METHODS

We examined associations between residential greenness [measured using satellite-derived Normalized Difference Vegetation Index (NDVI) within 100 m of study participants' homes] and birth outcomes in a cohort of 64,705 singleton births (from 1999-2002) in Vancouver, British Columbia, Canada. We also evaluated associations after adjusting for spatially correlated built environmental factors that may influence birth outcomes, including exposure to air pollution and noise, neighborhood walkability, and distance to the nearest park.

RESULTS

An interquartile increase in greenness (0.1 in residential NDVI) was associated with higher term birth weight (20.6 g; 95% CI: 16.5, 24.7) and decreases in the likelihood of small for gestational age, very preterm (< 30 weeks), and moderately preterm (30-36 weeks) birth. Associations were robust to adjustment for air pollution and noise exposures, neighborhood walkability, and park proximity.

CONCLUSIONS

Increased residential greenness was associated with beneficial birth outcomes in this population-based cohort. These associations did not change after adjusting for other spatially correlated built environment factors, suggesting that alternative pathways (e.g., psychosocial and psychological mechanisms) may underlie associations between residential greenness and birth outcomes.

The association of PM(2.5) with full term low birth weight at different spatial scales

There is interest in determining the relationship between fine particulate matter air pollution and various health outcomes, including birth outcomes such as term low birth weight. Previous studies have come to different conclusions. In this study we consider whether the effect may vary by location and gestational period. We also compare results when using different spatial resolutions for the air concentration estimates. Among the seven states considered, New Jersey and New York had the highest PM2.5 levels (average full gestation period exposures of 13 µg/m(3)) and the largest rate of low birth weight births (2.6 and 2.8%, respectively); conversely Utah and Minnesota had the lowest PM2.5 levels (9 µg/m(3)) and the lowest rates of low birth weight births (2.1 and1.9%, respectively). There is an association between PM2.5 exposure and low birth weight in New York for the full gestation period and all three trimesters, in Minnesota for the full gestation period and the first and third trimesters, and in New Jersey for the full gestation period and the first trimester. When we pooled the data across states, the OR for the full gestation period was 1.030 (95% CI: 1.022-1.037) and it was highest for the first trimester (OR 1.018; CI: 1.013-1.022) and decreasing during the later trimesters. When we used a finer spatial resolution, the strengths of the associations tended to diminish and were no longer statistically significant. We consider reasons why these differences may occur and their implications for evaluating the effects of PM2.5 on birth outcomes.

Fast inverse distance weighting-based spatiotemporal interpolation: a web-based application of interpolating daily fine particulate matter PM2:5 in the contiguous U.S. using parallel programming and k-d tree

Epidemiological studies have identified associations between mortality and changes in concentration of particulate matter. These studies have highlighted the public concerns about health effects of particulate air pollution. Modeling fine particulate matter PM_2.5 exposure risk and monitoring day-to-day changes in PM_2.5 concentration is a critical step for understanding the pollution problem and embarking on the necessary remedy. This research designs, implements and compares two inverse distance weighting (IDW)-based spatiotemporal interpolation methods, in order to assess the trend of daily PM_2.5 concentration for the contiguous United States over the year of 2009, at both the census block group level and county level. Traditionally, when handling spatiotemporal interpolation, researchers tend to treat space and time separately and reduce the spatiotemporal interpolation problems to a sequence of snapshots of spatial interpolations. In this paper, PM_2.5 data interpolation is conducted in the continuous space-time domain by integrating space and time simultaneously, using the so-called extension approach. Time values are calculated with the help of a factor under the assumption that spatial and temporal dimensions are equally important when interpolating a continuous changing phenomenon in the space-time domain. Various IDW-based spatiotemporal interpolation methods with different parameter configurations are evaluated by cross-validation. In addition, this study explores computational issues (computer processing speed) faced during implementation of spatiotemporal interpolation for huge data sets. Parallel programming techniques and an advanced data structure, named k-d tree, are adapted in this paper to address the computational challenges. Significant computational improvement has been achieved. Finally, a web-based spatiotemporal IDW-based interpolation application is designed and implemented where users can visualize and animate spatiotemporal interpolation results.

Exposure to fine particulate matter during pregnancy and risk of preterm birth among women in New Jersey, Ohio, and Pennsylvania, 2000-2005

BACKGROUND

Particulate matter ≤ 2.5 μm in aerodynamic diameter (PM2.5) has been variably associated with preterm birth (PTB).

OBJECTIVE

We classified PTB into four categories (20-27, 28-31, 32-34, and 35-36 weeks completed gestation) and estimated risk differences (RDs) for each category in association with a 1-μg/m3 increase in PM2.5 exposure during each week of gestation.

METHODS

We assembled a cohort of singleton pregnancies that completed ≥ 20 weeks of gestation during 2000-2005 using live birth certificate data from three states (Pennsylvania, Ohio, and New Jersey) (n = 1,940,213; 8% PTB). We estimated mean PM2.5 exposures for each week of gestation from monitor-corrected Community Multi-Scale Air Quality modeling data. RDs were estimated using modified Poisson linear regression and adjusted for maternal race/ethnicity, marital status, education, age, and ozone.

RESULTS

RD estimates varied by exposure window and outcome period. Average PM2.5 exposure during the fourth week of gestation was positively associated with all PTB outcomes, although magnitude varied by PTB category [e.g., for a 1-μg/m3 increase, RD = 11.8 (95% CI: -6, 29.2); RD = 46 (95% CI: 23.2, 68.9); RD = 61.1 (95% CI: 22.6, 99.7); and RD = 28.5 (95% CI: -39, 95.7) for preterm births during 20-27, 28-31, 32-34, and 35-36 weeks, respectively]. Exposures during the week of birth and the 2 weeks before birth also were positively associated with all PTB categories.

CONCLUSIONS

Exposures beginning around the time of implantation and near birth appeared to be more strongly associated with PTB than exposures during other time periods. Because particulate matter exposure is ubiquitous, evidence of effects of PM2.5 exposure on PTB, even if small in magnitude, is cause for concern.

Experiences of a rail yard community: life is hard

Community groups and local air pollution control agencies have identified the San Bernardino Railyard (SBR) as a significant public health and environmental justice issue. In response, the authors conducted a comprehensive study with community members living in close proximity to the rail yard. The purpose of this article is to share the community's perceptions about the rail yard and ideas on sustainable change. A qualitative study using key informant interviews and focus group discussions was conducted and resulted in four emerging themes. Themes emerged as follows: "health as an unattainable value," "air quality challenges," "rail yard pros and cons," and "violence and unemployment ripple effect." Community participants expressed concern for poor air quality, but other challenges took priority. The authors' findings suggest that future mitigation work to reduce air pollution exposure should not only focus on reducing risk from air pollution but address significant co-occurring community challenges. A "Health in All Policies" approach is warranted in addressing impacted communities in close proximity to the goods movement industry.

The Association between Airborne PM2.5 Chemical Constituents and Birth Weight-Implication of Buffer Exposure Assignment

Several papers reported associations between airborne fine particulate matter (PM_2.5) and birth weight, though findings are inconsistent across studies. Conflicting results might be due to (1) different PM_2.5 chemical structure across locations, and (2) various exposure assignment methods across studies even among the studies that use ambient monitors to assess exposure. We investigated associations between birth weight and PM_2.5 chemical constituents, considering issues arising from choice of buffer size (i.e. distance between residence and pollution monitor). We estimated the association between each pollutant and term birth weight applying buffers of 5 to 30km in Connecticut (2000-2006), in the New England region of the U.S. We also investigated the implication of the choice of buffer size in relation to population characteristics, such as socioeconomic status. Results indicate that some PM_2.5 chemical constituents, such as nitrate, are associated with lower birth weight and appear more harmful than other constituents. However, associations vary with buffer size and the implications of different buffer sizes may differ by pollutant. A homogeneous pollutant level within a certain distance is a common assumption in many environmental epidemiology studies, but the validity of this assumption may vary by pollutant. Furthermore, we found that areas close to monitors reflect more minority and lower socio-economic populations, which implies that different exposure approaches may result in different types of study populations. Our findings demonstrate that choosing an exposure method involves key tradeoffs of the impacts of exposure misclassification, sample size, and population characteristics.

The Association between Airborne PM2.5 Chemical Constituents and Birth Weight-Implication of Buffer Exposure Assignment

Several papers reported associations between airborne fine particulate matter (PM_2.5) and birth weight, though findings are inconsistent across studies. Conflicting results might be due to (1) different PM_2.5 chemical structure across locations, and (2) various exposure assignment methods across studies even among the studies that use ambient monitors to assess exposure. We investigated associations between birth weight and PM_2.5 chemical constituents, considering issues arising from choice of buffer size (i.e. distance between residence and pollution monitor). We estimated the association between each pollutant and term birth weight applying buffers of 5 to 30km in Connecticut (2000-2006), in the New England region of the U.S. We also investigated the implication of the choice of buffer size in relation to population characteristics, such as socioeconomic status. Results indicate that some PM_2.5 chemical constituents, such as nitrate, are associated with lower birth weight and appear more harmful than other constituents. However, associations vary with buffer size and the implications of different buffer sizes may differ by pollutant. A homogeneous pollutant level within a certain distance is a common assumption in many environmental epidemiology studies, but the validity of this assumption may vary by pollutant. Furthermore, we found that areas close to monitors reflect more minority and lower socio-economic populations, which implies that different exposure approaches may result in different types of study populations. Our findings demonstrate that choosing an exposure method involves key tradeoffs of the impacts of exposure misclassification, sample size, and population characteristics.

Maternal residential proximity to major roads in north west England and adverse pregnancy outcomes

OBJECTIVE

To investigate the effects of maternal residential proximity to major roads on adverse pregnancy outcomes.

METHODS

Major road networks in North West England were linked to the maternal residence of 190,909 births (2004 to 2008). Distance between the residence and the nearest major road was calculated and dichotomized at 200 m. Logistic regression analyses were performed to investigate the association between distance to the major road with small for gestational age, low birth weight, and preterm birth. Analyses were adjusted for maternal age, ethnicity, socioeconomic status, parity, birth season, smoking, and body mass index.

RESULTS

No significant associations were observed between preterm birth (odds ratio [OR] = 1.04; 95% confidence interval [CI] = 0.98 to 1.11), low birth weight (OR = 0.99; 95% CI = 0.93 to 1.05) and small for gestational age (OR = 1.00; 95% CI = 0.95 to 1.06) and living less than 200 m from a major road.

CONCLUSIONS

These results, from a study with high statistical power, suggest that living less than 200 m from a major road per se does not pose any great risk of an adverse perinatal outcome. Nevertheless, it may be limited to this geographic location. Further work is needed to quantify individual pollutant effects in pregnancy.

Associations between prenatal exposure to air pollution, small for gestational age, and term low birthweight in a state-wide birth cohort

A range of health effects, including adverse pregnancy outcomes, have been associated with exposure to ambient concentrations of particulate matter (PM) and ozone (O3). The objective of this study was to determine whether maternal exposure to fine particulate matter (PM2.5) and O3 during pregnancy is associated with the risk of term low birthweight and small for gestational age infants in both single and co-pollutant models. Term low birthweight and small for gestational age were determined using all birth certificates from North Carolina from 2003 to 2005. Ambient air concentrations of PM2.5 and O3 were predicted using a hierarchical Bayesian model of air pollution that combined modeled air pollution estimates from the EPA׳s Community Multi-Scale Air Quality (CMAQ) model with air monitor data measured by the EPA׳s Air Quality System. Binomial regression, adjusted for multiple potential confounders, was performed. In adjusted single-pollutant models for the third trimester, O3 concentration was positively associated with small for gestational age and term low birthweight births [risk ratios for an interquartile range increase in O3: 1.16 (95% CI 1.11, 1.22) for small for gestational age and 2.03 (95% CI 1.80, 2.30) for term low birthweight]; however, inverse or null associations were observed for PM2.5 [risk ratios for an interquartile range increase in PM2.5: 0.97 (95% CI 0.95, 0.99) for small for gestational age and 1.01 (95% CI 0.97, 1.06) for term low birthweight]. Findings were similar in co-pollutant models and linear models of birthweight. These results suggest that O3 concentrations in both urban and rural areas may be associated with an increased risk of term low birthweight and small for gestational age births.

Seasonality of fetal trisomy 21--have ambient air pollutants played a role?

OBJECTIVE

To examine the seasonality of fetal trisomy 21 and its relationship with ambient air pollutants.

METHODS

The averaged incidence by month-of-conception of the 113 cases (2002-2009) in our registry was correlated with month of conception and monthly ambient levels of nitrogen oxides (NOx, NO and NO2), sulfur dioxide, carbon monoxide, and ozone as reported by the Hong Kong Environmental Protection Department at the month of, and four-week after, conception.

RESULTS

The incidence was highest in February (3.45/1000 births) and lowest in October (1.28/1000 births), and showed a significant difference (p = 0.003) and positive correlation (p = 0.003) from winter to autumn. It was also correlated with NO (p = 0.017) and inversely with ozone (p = 0.014) at conception.

CONCLUSIONS

Seasonal variation in incidence of fetal trisomy 21 was correlated with ambient levels of nitric oxides and ozone. The role of environmental pollutants on fetal aneuploidy warrants further investigation.

Construction of an environmental quality index for public health research

BACKGROUND

A more comprehensive estimate of environmental quality would improve our understanding of the relationship between environmental conditions and human health. An environmental quality index (EQI) for all counties in the U.S. was developed.

METHODS

The EQI was developed in four parts: domain identification; data source acquisition; variable construction; and data reduction. Five environmental domains (air, water, land, built and sociodemographic) were recognized. Within each domain, data sources were identified; each was temporally (years 2000-2005) and geographically (county) restricted. Variables were constructed for each domain and assessed for missingness, collinearity, and normality. Domain-specific data reduction was accomplished using principal components analysis (PCA), resulting in domain-specific indices. Domain-specific indices were then combined into an overall EQI using PCA. In each PCA procedure, the first principal component was retained. Both domain-specific indices and overall EQI were stratified by four rural-urban continuum codes (RUCC). Higher values for each index were set to correspond to areas with poorer environmental quality.

RESULTS

Concentrations of included variables differed across rural-urban strata, as did within-domain variable loadings, and domain index loadings for the EQI. In general, higher values of the air and sociodemographic indices were found in the more metropolitan areas and the most thinly populated areas have the lowest values of each of the domain indices. The less-urbanized counties (RUCC 3) demonstrated the greatest heterogeneity and range of EQI scores (-4.76, 3.57) while the thinly populated strata (RUCC 4) contained counties with the most positive scores (EQI score ranges from -5.86, 2.52).

CONCLUSION

The EQI holds promise for improving our characterization of the overall environment for public health. The EQI describes the non-residential ambient county-level conditions to which residents are exposed and domain-specific EQI loadings indicate which of the environmental domains account for the largest portion of the variability in the EQI environment. The EQI was constructed for all counties in the United States, incorporating a variety of data to provide a broad picture of environmental conditions. We undertook a reproducible approach that primarily utilized publically-available data sources.

Construction of an environmental quality index for public health research

BACKGROUND

A more comprehensive estimate of environmental quality would improve our understanding of the relationship between environmental conditions and human health. An environmental quality index (EQI) for all counties in the U.S. was developed.

METHODS

The EQI was developed in four parts: domain identification; data source acquisition; variable construction; and data reduction. Five environmental domains (air, water, land, built and sociodemographic) were recognized. Within each domain, data sources were identified; each was temporally (years 2000-2005) and geographically (county) restricted. Variables were constructed for each domain and assessed for missingness, collinearity, and normality. Domain-specific data reduction was accomplished using principal components analysis (PCA), resulting in domain-specific indices. Domain-specific indices were then combined into an overall EQI using PCA. In each PCA procedure, the first principal component was retained. Both domain-specific indices and overall EQI were stratified by four rural-urban continuum codes (RUCC). Higher values for each index were set to correspond to areas with poorer environmental quality.

RESULTS

Concentrations of included variables differed across rural-urban strata, as did within-domain variable loadings, and domain index loadings for the EQI. In general, higher values of the air and sociodemographic indices were found in the more metropolitan areas and the most thinly populated areas have the lowest values of each of the domain indices. The less-urbanized counties (RUCC 3) demonstrated the greatest heterogeneity and range of EQI scores (-4.76, 3.57) while the thinly populated strata (RUCC 4) contained counties with the most positive scores (EQI score ranges from -5.86, 2.52).

CONCLUSION

The EQI holds promise for improving our characterization of the overall environment for public health. The EQI describes the non-residential ambient county-level conditions to which residents are exposed and domain-specific EQI loadings indicate which of the environmental domains account for the largest portion of the variability in the EQI environment. The EQI was constructed for all counties in the United States, incorporating a variety of data to provide a broad picture of environmental conditions. We undertook a reproducible approach that primarily utilized publically-available data sources.

Health effects of ambient air pollution: do different methods for estimating exposure lead to different results?

BACKGROUND

Spatially resolved exposure models are increasingly used in epidemiology. We previously reported that, although exhibiting a moderate correlation, pregnancy nitrogen dioxide (NO2) levels estimated by the nearest air quality monitoring station (AQMS) model and a geostatistical model, showed similar associations with infant birth weight.

OBJECTIVES

We extended this study by comparing a total of four exposure models, including two highly spatially resolved models: a land-use regression (LUR) model and a dispersion model. Comparisons were made in terms of predicted NO2 and particle (aerodynamic diameter<10 μm, PM10) exposure and adjusted association with birth weight.

METHODS

The four exposure models were implemented in two French metropolitan areas where 1026 pregnant women were followed as part of the EDEN mother-child cohort.

RESULTS

Correlations between model predictions were high (≥ 0.70), except for NO2 between the AQMS and both the LUR (r = 0.54) and dispersion models (r = 0.63). Spatial variations as estimated by the AQMS model were greater for NO2 (95%) than for PM10 (22%). The direction of effect estimates of NO2 on birth weight varied according to the exposure model, while PM10 effect estimates were more consistent across exposure models.

CONCLUSIONS

For PM10, highly spatially resolved exposure model agreed with the poor spatial resolution AQMS model in terms of estimated pollutant levels and health effects. For more spatially heterogeneous pollutants like NO2, although predicted levels from spatially resolved models (all but AQMS) agreed with each other, our results suggest that some may disagree with each other as well as with the AQMS regarding the direction of the estimated health effects.

Quantifying traffic exposure

Living near traffic adversely affects health outcomes. Traffic exposure metrics include distance to high-traffic roads, traffic volume on nearby roads, traffic within buffer distances, measured pollutant concentrations, land-use regression estimates of pollution concentrations, and others. We used Geographic Information System software to explore a new approach using traffic count data and a kernel density calculation to generate a traffic density surface with a resolution of 50 m. The density value in each cell reflects all the traffic on all the roads within the distance specified in the kernel density algorithm. The effect of a given roadway on the raster cell value depends on the amount of traffic on the road segment, its distance from the raster cell, and the form of the algorithm. We used a Gaussian algorithm in which traffic influence became insignificant beyond 300 m. This metric integrates the deleterious effects of traffic rather than focusing on one pollutant. The density surface can be used to impute exposure at any point, and it can be used to quantify integrated exposure along a global positioning system route. The traffic density calculation compares favorably with other metrics for assessing traffic exposure and can be used in a variety of applications.

Seasonal ambient air pollution correlates strongly with spontaneous abortion in Mongolia

Background

Air pollution is a major health challenge worldwide and has previously been strongly associated with adverse reproductive health. This study aimed to examine the association between spontaneous abortion and seasonal variation of air pollutants in Ulaanbaatar, Mongolia.

Methods

Monthly average O₃, SO₂, NO₂, CO, PM₁₀ and PM_2.5 levels were measured at Mongolian Government Air Quality Monitoring stations. The medical records of 1219 women admitted to the hospital due to spontaneous abortion between 2009–2011 were examined retrospectively. Fetal deaths per calendar month from January-December, 2011 were counted and correlated with mean monthly levels of various air pollutants by means of regression analysis.

Results

Regression of ambient pollutants against fetal death as a dose–response toxicity curve revealed very strong dose–response correlations for SO₂ r > 0.9 (p < 0.001) while similarly strongly significant correlation coefficients were found for NO₂ (r > 0.8), CO (r > 0.9), PM₁₀ (r > 0.9) and PM_2.5 (r > 0.8), (p < 0.001), indicating a strong correlation between air pollution and decreased fetal wellbeing.

Conclusion

The present study identified alarmingly strong statistical correlations between ambient air pollutants and spontaneous abortion. Further studies need to be done to examine possible correlations between personal exposure to air pollutants and pregnancy loss.

National patterns in environmental injustice and inequality: outdoor NO2 air pollution in the United States

We describe spatial patterns in environmental injustice and inequality for residential outdoor nitrogen dioxide (NO2) concentrations in the contiguous United States. Our approach employs Census demographic data and a recently published high-resolution dataset of outdoor NO2 concentrations. Nationally, population-weighted mean NO2 concentrations are 4.6 ppb (38%, p<0.01) higher for nonwhites than for whites. The environmental health implications of that concentration disparity are compelling. For example, we estimate that reducing nonwhites' NO2 concentrations to levels experienced by whites would reduce Ischemic Heart Disease (IHD) mortality by ∼7,000 deaths per year, which is equivalent to 16 million people increasing their physical activity level from inactive (0 hours/week of physical activity) to sufficiently active (>2.5 hours/week of physical activity). Inequality for NO2 concentration is greater than inequality for income (Atkinson Index: 0.11 versus 0.08). Low-income nonwhite young children and elderly people are disproportionately exposed to residential outdoor NO2. Our findings establish a national context for previous work that has documented air pollution environmental injustice and inequality within individual US metropolitan areas and regions. Results given here can aid policy-makers in identifying locations with high environmental injustice and inequality. For example, states with both high injustice and high inequality (top quintile) for outdoor residential NO2 include New York, Michigan, and Wisconsin.

Long-term exposure to traffic-related air pollution and progression of carotid artery atherosclerosis: a prospective cohort study

OBJECTIVES

Epidemiological studies have demonstrated associations between long-term exposure to traffic-related air pollution and coronary heart disease (CHD). Atherosclerosis is the principal pathological process responsible for CHD events, but effects of traffic-related air pollution on progression of atherosclerosis are not clear. This study aimed to investigate associations between long-term exposure to traffic-related air pollution and progression of carotid artery atherosclerosis.

SETTING

Healthy volunteers in metropolitan Vancouver, Canada.

PARTICIPANTS AND OUTCOME MEASURES

509 participants aged 30-65 years were recruited and followed for approximately 5 years. At baseline and end of follow-up, participants underwent carotid artery ultrasound examinations to assess atherosclerosis severity, including carotid intima-media thickness, plaque area, plaque number and total area. Annual change of each atherosclerosis marker during the follow-up period was calculated as the difference between these two measurements divided by years of follow-up. Living close to major roads was defined as ≤150 m from a highway or ≤50 m from a major road. Residential exposures to traffic-related air pollutants including black carbon, fine particles, nitrogen dioxide and nitric oxide were estimated using high-resolution land-use regression models. The data were analysed using general linear models adjusting for various covariates.

RESULTS

At baseline, there were no significant differences in any atherosclerosis markers between participants living close to and those living away from major roads. After follow-up, the differences in annual changes of these markers between these two groups were small and not statistically significant. Also, no significant associations were observed with concentrations of traffic-related air pollutants including black carbon, fine particles, nitrogen dioxide and nitric oxide.

CONCLUSIONS

This study did not find significant associations between traffic-related air pollution and progression of carotid artery atherosclerosis in a region with lower levels and smaller contrasts of ambient air pollution.

Birth outcomes and maternal residential proximity to natural gas development in rural Colorado

BACKGROUND

Birth defects are a leading cause of neonatal mortality. Natural gas development (NGD) emits several potential teratogens, and U.S. production of natural gas is expanding.

OBJECTIVES

We examined associations between maternal residential proximity to NGD and birth outcomes in a retrospective cohort study of 124,842 births between 1996 and 2009 in rural Colorado.

METHODS

We calculated inverse distance weighted natural gas well counts within a 10-mile radius of maternal residence to estimate maternal exposure to NGD. Logistic regression, adjusted for maternal and infant covariates, was used to estimate associations with exposure tertiles for congenital heart defects (CHDs), neural tube defects (NTDs), oral clefts, preterm birth, and term low birth weight. The association with term birth weight was investigated using multiple linear regression.

RESULTS

Prevalence of CHDs increased with exposure tertile, with an odds ratio (OR) of 1.3 for the highest tertile (95% CI: 1.2, 1.5); NTD prevalence was associated with the highest tertile of exposure (OR = 2.0; 95% CI: 1.0, 3.9, based on 59 cases), compared with the absence of any gas wells within a 10-mile radius. Exposure was negatively associated with preterm birth and positively associated with fetal growth, although the magnitude of association was small. No association was found between exposure and oral clefts.

CONCLUSIONS

In this large cohort, we observed an association between density and proximity of natural gas wells within a 10-mile radius of maternal residence and prevalence of CHDs and possibly NTDs. Greater specificity in exposure estimates is needed to further explore these associations.

Outdoor air pollution, preterm birth, and low birth weight: analysis of the world health organization global survey on maternal and perinatal health

BACKGROUND

Inhaling fine particles (particulate matter with diameter ≤ 2.5 μm; PM2.5) can induce oxidative stress and inflammation, and may contribute to onset of preterm labor and other adverse perinatal outcomes.

OBJECTIVES

We examined whether outdoor PM2.5 was associated with adverse birth outcomes among 22 countries in the World Health Organization Global Survey on Maternal and Perinatal Health from 2004 through 2008.

METHODS

Long-term average (2001-2006) estimates of outdoor PM2.5 were assigned to 50-km-radius circular buffers around each health clinic where births occurred. We used generalized estimating equations to determine associations between clinic-level PM2.5 levels and preterm birth and low birth weight at the individual level, adjusting for seasonality and potential confounders at individual, clinic, and country levels. Country-specific associations were also investigated.

RESULTS

Across all countries, adjusting for seasonality, PM2.5 was not associated with preterm birth, but was associated with low birth weight [odds ratio (OR) = 1.22; 95% CI: 1.07, 1.39 for fourth quartile of PM2.5 (> 20.2 μg/m3) compared with the first quartile (< 6.3 μg/m3)]. In China, the country with the largest PM2.5 range, preterm birth and low birth weight both were associated with the highest quartile of PM2.5 only, which suggests a possible threshold effect (OR = 2.54; CI: 1.42, 4.55 and OR = 1.99; CI: 1.06, 3.72 for preterm birth and low birth weight, respectively, for PM2.5 ≥ 36.5 μg/m3 compared with PM2.5 < 12.5 μg/m3).

CONCLUSIONS

Outdoor PM2.5 concentrations were associated with low birth weight but not preterm birth. In rapidly developing countries, such as China, the highest levels of air pollution may be of concern for both outcomes.

Prenatal air pollution exposure and ultrasound measures of fetal growth in Los Angeles, California

BACKGROUND

Few previous studies examined the impact of prenatal air pollution exposures on fetal development based on ultrasound measures during pregnancy.

METHODS

In a prospective birth cohort of more than 500 women followed during 1993-1996 in Los Angeles, California, we examined how air pollution impacts fetal growth during pregnancy. Exposure to traffic related air pollution was estimated using CALINE4 air dispersion modeling for nitrogen oxides (NOx) and a land use regression (LUR) model for nitrogen monoxide (NO), nitrogen dioxide (NO2) and NOx. Exposures to carbon monoxide (CO), NO2, ozone (O3) and particles <10μm in aerodynamic diameter (PM10) were estimated using government monitoring data. We employed a linear mixed effects model to estimate changes in fetal size at approximately 19, 29 and 37 weeks gestation based on ultrasound.

RESULTS

Exposure to traffic-derived air pollution during 29 to 37 weeks was negatively associated with biparietal diameter at 37 weeks gestation. For each interquartile range (IQR) increase in LUR-based estimates of NO, NO2 and NOx, or freeway CALINE4 NOx we estimated a reduction in biparietal diameter of 0.2-0.3mm. For women residing within 5km of a monitoring station, we estimated biparietal diameter reductions of 0.9-1.0mm per IQR increase in CO and NO2. Effect estimates were robust to adjustment for a number of potential confounders. We did not observe consistent patterns for other growth endpoints we examined.

CONCLUSIONS

Prenatal exposure to traffic-derived pollution was negatively associated with fetal head size measured as biparietal diameter in late pregnancy.

Exposure to air pollution and respiratory symptoms during the first 7 years of life in an Italian birth cohort

Background

Ambient air pollution has been consistently associated with exacerbation of respiratory diseases in schoolchildren, but the role of early exposure to traffic-related air pollution in the first occurrence of respiratory symptoms and asthma is not yet clear.

Methods

We assessed the association between indexes of exposure to traffic-related air pollution during different periods of life and respiratory outcomes in a birth cohort of 672 newborns (Rome, Italy). Direct interviews of the mother were conducted at birth and at 6, 15 months, 4 and 7 years. Exposure to traffic-related air pollution was assessed for each residential address during the follow-up period using a Land-Use Regression model (LUR) for nitrogen dioxide (NO₂) and a Geographic Information System (GIS) variable of proximity to high-traffic roads (HTR) (>10 000vehicles/day). We used age-specific NO₂ levels to develop indices of exposure at birth, current, and lifetime time-weighted average. The association of NO₂ and traffic proximity with respiratory disorders were evaluated using logistic regression in a longitudinal approach (Generalised Estimating Equation). The exposure indexes were used as continuous and categorical variables (cut-off points based on the 75th percentile for NO₂ and the 25th percentile for distance from HTRs).

Results

The average NO₂ exposure level at birth was 37.2 μg/m³ (SD 7.2, 10–90th range 29.2–46.1). There were no statistical significant associations between the exposure indices and the respiratory outcomes in the longitudinal model. The odds ratios for a 10-µg/m³ increase in time-weighted average NO₂ exposure were: asthma incidence OR=1.09; 95 CI% 0.78 to 1.52, wheezing OR=1.07; 95 CI% 0.90 to 1.28, shortness of breath with wheezing OR=1.16; 95 CI% 0.94 to 1.43, cough or phlegm apart from cold OR=1.11; 95 CI% 0.92 to 1.33, and otitis OR=1.08; 95 CI% 0.89 to 1.32. Stronger but not significant associations were found considering the 75th percentile of the NO₂ distribution as a cut-off, especially for incidence of asthma and prevalence of wheeze (OR=1.41; 95 CI% 0.88 to 2.28 and OR=1.27; 95 CI% 0.95 to 1.70, respectively); the highest OR was found for wheezing (OR=2.29; 95 CI% 1.15 to 4.56) at the 7-year follow-up. No association was found with distance from HTRs.

Conclusions

Exposure to traffic-related air pollution is only weakly associated with respiratory symptoms in young children in the first 7 years of life.

Traffic-related air pollution and congenital anomalies in Barcelona

BACKGROUND

A recent meta-analysis suggested evidence for an effect of exposure to ambient air pollutants on risk of certain congenital heart defects. However, few studies have investigated the effects of traffic-related air pollutants with sufficient spatial accuracy.

OBJECTIVES

We estimated associations between congenital anomalies and exposure to traffic-related air pollution in Barcelona, Spain.

METHOD

Cases with nonchromosomal anomalies (n = 2,247) and controls (n = 2,991) were selected from the Barcelona congenital anomaly register during 1994-2006. Land use regression models from the European Study of Cohorts for Air Pollution Effects (ESCAPE), were applied to residential addresses at birth to estimate spatial exposure to nitrogen oxides and dioxide (NOx, NO2), particulate matter with diameter ≤ 10 μm (PM10), 10-2.5 μm (PMcoarse), ≤ 2.5 μm (PM2.5), and PM2.5 absorbance. Spatial estimates were adjusted for temporal trends using data from routine monitoring stations for weeks 3-8 of each pregnancy. Logistic regression models were used to calculate odds ratios (ORs) for 18 congenital anomaly groups associated with an interquartile-range (IQR) increase in exposure estimates.

RESULTS

In spatial and spatiotemporal exposure models, we estimated statistically significant associations between an IQR increase in NO2 (12.2 μg/m3) and coarctation of the aorta (ORspatiotemporal = 1.15; 95% CI: 1.01, 1.31) and digestive system defects (ORspatiotemporal = 1.11; 95% CI: 1.00, 1.23), and between an IQR increase in PMcoarse (3.6 μg/m3) and abdominal wall defects (ORspatiotemporal = 1.93; 95% CI: 1.37, 2.73). Other statistically significant increased and decreased ORs were estimated based on the spatial model only or the spatiotemporal model only, but not both.

CONCLUSIONS

Our results overall do not indicate an association between traffic-related air pollution and most groups of congenital anomalies. Findings for coarctation of the aorta are consistent with those of the previous meta-analysis.

CITATION

Schembari A, Nieuwenhuijsen MJ, Salvador J, de Nazelle A, Cirach M, Dadvand P, Beelen R, Hoek G, Basagaña X, Vrijheid M. 2014. Traffic-related air pollution and congenital anomalies in Barcelona. Environ Health Perspect 122:317-323; http://dx.doi.org/10.1289/ehp.1306802.

A retrospective approach to assess human health risks associated with growing air pollution in urbanized area of Thar Desert, western Rajasthan, India

: Air pollution has been a matter of great concern globally because of the associated health risks to individuals. The situation is getting worse in developing countries with more urbanization, industrialization and more importantly the rapidly growing population posing a threat to human life in the form of pulmonary, cardiovascular, carcinogenic or asthmatic diseases by accumulating toxic pollutants, harmful gases, metals, hydrocarbons etc.

OBJECTIVE

The present study was undertaken to assess the magnitude of ambient air pollutants and their human health risks like respiratory ailments, infectious diseases, cardiovascular diseases and cancer using a Retrospective Approach of Bart Ostra.

METHODOLOGY

The parameters PM2.5, PM10, NOx, SO2, NH3 and O3 were monitored at all selected study sites monitored through a high volume sampler (APM 451 Envirotech, Envirotech Instruments Pvt. Ltd., New Delhi, India). Retrospective Approach was used for assessment of risk factors and disease burden of respiratory and cardiopulmonary health problems.

RESULTS

Environmental burden of disease showed that the problem of health related to air pollution is a main concern particularly in the growing cities of India. High to critical level of air pollution including PM10, PM2.5, NOx, SO2, NH3 and O3 was observed in all seasons at traffic intersections and commercial sites. The respiratory infections (25% incidence in population exposed to indoor smoke problems) and a prevalence of asthma/COPD (4.4%) in households exposed to high vehicular pollution along with signs of coronary artery/heart disease and/or hypertension and cancers (37.9-52.2%), were reported requiring preventive measures.

CONCLUSION

The study reflects a great concern for the mankind with the need of having streamline ways to limit air pollution and emphasize upon efficiently determining the risk of illness upon exposure to air pollution.

Fine particulate matter and risk of preterm birth in Connecticut in 2000-2006: a longitudinal study

Several studies have examined associations between particulate matter with aerodynamic diameter of 2.5 µm or less (PM2.5) and preterm birth, but it is uncertain whether results were affected by individual predispositions (e.g., genetic factors, social conditions) that might vary considerably between women. We tested the hypothesis that a woman is at greater risk of preterm delivery when she has had elevated exposure to ambient PM2.5 during a pregnancy than when she has not by comparing pregnancies in the same woman. From 271,204 births, we selected 29,175 women who had vaginal singleton livebirths at least twice in Connecticut in 2000-2006 (n = 61,688 births). Analyses matched pregnancies to the same woman. Adjusted odds ratios per interquartile range (2.33-µg/m(3)) increase in PM2.5 in the first trimester, second trimester, third trimester, and whole pregnancy were 1.07 (95% confidence interval (CI): 1.00, 1.15), 0.96 (95% CI: 0.90, 1.03), 1.03 (95% CI: 0.97, 1.08), and 1.13 (95% CI: 1.01, 1.28), respectively. Among Hispanic women, the odds ratio per interquartile range increase in whole-pregnancy exposure was 1.31 (95% CI: 1.00, 1.73). Pregnancies with elevated PM2.5 exposure were more likely to result in preterm birth than were other pregnancies to the same woman at lower exposure. Associations were most pronounced in the first trimester and among Hispanic women.

Travel patterns during pregnancy: comparison between Global Positioning System (GPS) tracking and questionnaire data

BACKGROUND

Maternal exposures to traffic-related air pollution have been associated with adverse pregnancy outcomes. Exposures to traffic-related air pollutants are strongly influenced by time spent near traffic. However, little is known about women's travel activities during pregnancy and whether questionnaire-based data can provide reliable information on travel patterns during pregnancy.

OBJECTIVES

Examine women's in-vehicle travel behavior during pregnancy and examine the difference in travel data collected by questionnaire and global positioning system (GPS) and their potential for exposure error.

METHODS

We measured work-related travel patterns in 56 pregnant women using a questionnaire and one-week GPS tracking three times during pregnancy (<20 weeks, 20-30 weeks, and >30 weeks of gestation). We compared self-reported activities with GPS-derived trip distance and duration, and examined potentially influential factors that may contribute to differences. We also described in-vehicle travel behavior by pregnancy periods and influences of demographic and personal factors on daily travel times. Finally, we estimated personal exposure to particle-bound polycyclic aromatic hydrocarbon (PB-PAH) and examined the magnitude of exposure misclassification using self-reported vs. GPS travel data.

RESULTS

Subjects overestimated both trip duration and trip distance compared to the GPS data. We observed moderately high correlations between self-reported and GPS-recorded travel distance (home to work trips: r = 0.88; work to home trips: r = 0.80). Better agreement was observed between the GPS and the self-reported travel time for home to work trips (r = 0.77) than work to home trips (r = 0.64). The subjects on average spent 69 and 93 minutes traveling in vehicles daily based on the GPS and self-reported data, respectively. Longer daily travel time was observed among participants in early pregnancy, and during certain pregnancy periods in women with higher education attainment, higher income, and no children. When comparing self-reported vs. GPS data, we found that estimated personal exposure to PB-PAH did not differ remarkably at the population level, but the difference was large at an individual level.

CONCLUSION

Self-reported home-to-work data overestimated both trip duration and trip distance compared to GPS data. Significant differences in PAH exposure estimates were observed at individual level using self-reported vs. GPS data, which has important implications in air pollution epidemiological studies.