Prenatal Particulate Air Pollution and Asthma Onset in Urban Children. Identifying Sensitive Windows and Sex Differences

Abstract

Rationale: The influence of particulate air pollution on respiratory health starts in utero. Fetal lung growth and structural development occurs in stages; thus, effects on postnatal respiratory disorders may differ based on timing of exposure.Objectives: We implemented an innovative method to identify sensitive windows for effects of prenatal exposure to particulate matter with a diameter less than or equal to 2.5 mm (PM 2.5 ) on children's asthma development in an urban pregnancy cohort.Methods: Analyses included 736 full-term (>37 wk) children. Each mother's daily PM 2.5 exposure was estimated over gestation using a validated satellite-based spatiotemporal resolved model. Using distributed lag models, we examined associations between weekly averaged PM 2.5 levels over pregnancy and physician-diagnosed asthma in children by age 6 years. Effect modification by sex was also examined.Measurements and Main Results: Most mothers were ethnic minorities (54% Hispanic, 30% black), had 12 or fewer years of education (66%), and did not smoke in pregnancy (80%). In the sample as a whole, distributed lag models adjusting for child age, sex, and maternal factors (education, race and ethnicity, smoking, stress, atopy, prepregnancy obesity) showed that increased PM 2.5 exposure levels at 16-25 weeks gestation were significantly associated with early childhood asthma development. An interaction between PM 2.5 and sex was significant (P = 0.01) with sex-stratified analyses showing that the association exists only for boys.Conclusions: Higher prenatal PM 2.5 exposure at midgestation was associated with asthma development by age 6 years in boys. Methods to better characterize vulnerable windows may provide insight into underlying mechanisms.

Susceptibility Factors Relevant for the Association Between Long-Term Air Pollution Exposure and Incident Asthma

“…As epidemiological studies are either conducted among adults or among children, and often focus on a specific age range, few studies stratify the results according to age. However it is of special interest that one study reported higher incidence of asthma in children (even if only boys) who were more exposed in utero during 12-26 weeks of gestation pointing out to a possible prenatal susceptibility window [19]. This result is concordant with a study that found that prenatal exposure to air pollution was associated with long-term lung function deficits at preschool age [44].…”

“…In a pregnancy cohort in US [19], the association between in-utero exposure to PM 2.5 and asthma onset at age 6 showed a sensitive exposure window between 12-26 weeks of gestation for boys but not for girls, and the authors reported a significant interaction term for sex (p-interaction=0.01, OR(PM 2.5 *boys): 1.33(1.05-1.69)). In the five other studies, associations were similar in boys and girls: in children aged 6-9 years from the Chiba prefecture in Japan [30], the association between air pollution, measured as school proximity to traffic and asthma incidence was similar in boys and girls (OR(95%CI): 3.75(1.00-14.06) for boys and 4.06(0.91-18.10) for girls).…”

“…Seven studies stratified the effects of air pollution on asthma by sex [13,14,[17][18][19]30,35] in children.…”

A Review on Predicting Ground PM2.5 Concentration Using Satellite Aerosol Optical Depth

“…The distinctive feature of the model of Kloog et al is its inclusion of meteorological variables (such as temperature, wind speed and visibility) and land use variables (such as elevation, percentage of open spaces, area emissions, point emissions and distance to major roads) into the model, which is appropriate for studying acute and chronic health effects. Since then, many researchers, including Kloog, Madrigano, Chiu and others, have used MEM to study acute and chronic health effects [79,96,[130][131][132][133], and it has performed well. In 2012, by using GEOS AOD data and adding a surface reflection variable into MEM, Chudnovsky et al [35] showed a high predictive value of CV-R 2 = 0.920.…”

Particulate matter accumulation – further differences between native Prunus padusand non-native P. serotina

“…Epidemiological studies investigating the impact of particulate matter on the human population have shown a negative correlation between the amount of PM in air and human health (Jędrychowski et al, 2011;Weuve, 2012;Saravia et al, 2013;Hsu et al, 2015). It has been estimated that exposure to PM causes approximately 2.1 million premature deaths annually worldwide, associated with cardiopulmonary diseases and lung cancer (Silva et al, 2013).…”