JMIR Publications

ABSTRACT

Background:

The first 1000 days of life is a critical window for human health development. However, the associations between mixed exposure to air pollutants in the first 1000 days and asthma/wheezing in children has been poorly studied.

Objective:

We aimed to estimate the associations of prenatal and postnatal exposures to multiple ambient air pollutants (PM2.5, CO, SO2, NO2 and O3) with incidence of childhood asthma/wheezing, and to identify the potential sensitivity window of air pollution effects.

Methods:

A prospective birth cohort study was implemented to recruit pregnant women in the early pregnancy and to follow up them and their children. Maternal and their children’s exposures to air pollutants (PM2.5, CO, SO2, NO2 and O3) was assessed using a spatiotemporal land-use regression (ST-LUR) model. The quantile g-computation model (QG-comp) was used to estimate the joint associations of exposure to mixed air pollutants on the risk of asthma/wheezing in children.

Results:

A total of 3,725 children were included, of whom 392 (10.52%) were diagnosed with asthma/wheezing. Each quartile increase in exposure to mixed air pollutants during the second trimester of pregnancy, pseudoglandular, and canalicular stages was associated with an adjusted hazard ratio (HR) of 1.24 (95%CI: 1.04-1.47), 1.24 (95%CI: 1.03-1.51) and 1.23 (95%CI: 1.01-1.51), respectively. Moreover, the increments per quartile of exposure to mixed air pollutants was associated with HR of 1.65(95% CI: 1.30-2.10) and 2.53 (95% CI: 2.16-2.97) in the first one year and two years after birth, respectively.

Conclusions:

Mixed exposure to higher air pollutants in the first 1000 days of life may increase the risk of childhood asthma/wheezing. The second trimester, particularly pseudoglandular stage and the canalicular stage, and the first two years after birth may be the critical exposure window.