A life course approach to asthma and wheezing among young children caused by ozone: A prospective birth cohort in northern China.

BACKGROUND

Given differences in vulnerability of children in early life, a life course approach to asthma and wheezing (AW) in young children caused by ozone (O) is not fully understood.

METHODS

We conducted a birth cohort in Jinan, China from 2018 to 2021 to elucidate the onset model of childhood AW due to O exposure. An inverse distance weighted model was used for individual exposure assessment. The time-dependent Cox proportional-hazard model and logistic model were used to investigate the effects of O exposure on AW. Principal component analysis, interaction analysis, and distributed lag model were used to analyze the life course approach.

RESULTS

The cumulative incidence rate for AW among 6501 children aged 2 was 1.4%. A high level of O was related to AW (HR: 2.10, 95% CI: 1.31, 3.37). Only O exposure after birth was associated with AW, with an OR of 1.82 (1.08, 3.12), after adjusting for the effect before birth. Furthermore, adjusting for other air pollutants, the HR for the individual effect of high O exposure on AW was 2.44 (1.53, 3.89). Interestingly, P values for interactions for O and the principal components of other pollutants, as well as the characteristic variable of open windows were less than 0.1. Moreover, an increase in the IQR of O exposure at the 31st to 37th weeks before birth and the 1st to 105th weeks after birth was associated with an increase in the HRs for AW.

CONCLUSIONS

High-level of O exposure after birth could lead to AW among young children. Importantly, the AW onset model may include the risk factors accumulation and the sensitive period model. Specifically, there are two sensitive windows in early life, and the correlated insults between the high level of O and other pollutants as well as open windows in the asthma-inducing effect.