177 / 2023-05-01 23:14:11

Improved ambient air quality is associated with decreased prevalence of childhood asthma and infancy shortly after weaning is a sensitive exposure window

Particulate Matter, Uterus, Infancy, Wheezing, Early life Exposure

Background: The urban ambient air quality has been largely improved in the past decade. It is unknown whether childhood asthma prevalence is still increasing in ever top-ranking city of Shanghai, whether the improved air quality is beneficial for children’s asthma and what time window of exposure plays critical roles.

Methods: Using a repeat cross-sectional design, we analyzed the association between early life exposure to particles and wheezing/asthma in each individual and combined surveys in 2011 and 2019, respectively, in 11,825 preschool children in Shanghai.

Results: A significantly lower prevalence of doctor-diagnosed asthma(DDA)(6.6% vs. 10.5%, P <0.001) and wheezing(10.5% vs. 23.2%, P <0.001) was observed in 2019 compared to 2011. Exposure to fine particulate matter(PM_2.5), coarse particles(PM_2.5-10) and inhalable particles(PM₁₀) was decreased in 2019 by 6.3%, 35.4% and 44.7% in uterus and 24.3%, 20.2% and 31.8% in infancy, respectively. Multilevel log-binomial regression analysis showed exposure in infancy had independent association with wheezing/DDA adjusting for exposure in uterus. For each interquartile range(IQR) increase of infancy PM_2.5, PM_2.5-10 and PM₁₀ exposure, the odds ratios were 1.39(95% confidence interval(CI): 1.24-1.56), 1.51(95%CI:1.15-1.98) and 1.53 (95%CI:1.27-1.85) for DDA, respectively. The Distributed Lag Non-linear Model showed the sensitive exposure window(SEW) was 5.5-11months(m) after birth. Stratified analysis showed the SEWs were at or shortly after weaning, but only in those with <6m of exclusive breastfeeding.

Conclusions: Improved ambient particulate matter benefits in decreasing childhood asthma prevalence. We firstly reported the finding of SEW to particulate matter at or closely after weaning on childhood asthma.

Background: The urban ambient air quality has been largely improved in the past decade. It is unknown whether childhood asthma prevalence is still increasing in ever top-ranking city of Shanghai, whether the improved air quality is beneficial for children’s asthma and what time window of exposure plays critical roles.

Methods: Using a repeat cross-sectional design, we analyzed the association between early life exposure to particles and wheezing/asthma in each individual and combined surveys in 2011 and 2019, respectively, in 11,825 preschool children in Shanghai.

Results: A significantly lower prevalence of doctor-diagnosed asthma(DDA)(6.6% vs. 10.5%, P <0.001) and wheezing(10.5% vs. 23.2%, P <0.001) was observed in 2019 compared to 2011. Exposure to fine particulate matter(PM_2.5), coarse particles(PM_2.5-10) and inhalable particles(PM₁₀) was decreased in 2019 by 6.3%, 35.4% and 44.7% in uterus and 24.3%, 20.2% and 31.8% in infancy, respectively. Multilevel log-binomial regression analysis showed exposure in infancy had independent association with wheezing/DDA adjusting for exposure in uterus. For each interquartile range(IQR) increase of infancy PM_2.5, PM_2.5-10 and PM₁₀ exposure, the odds ratios were 1.39(95% confidence interval(CI): 1.24-1.56), 1.51(95%CI:1.15-1.98) and 1.53 (95%CI:1.27-1.85) for DDA, respectively. The Distributed Lag Non-linear Model showed the sensitive exposure window(SEW) was 5.5-11months(m) after birth. Stratified analysis showed the SEWs were at or shortly after weaning, but only in those with <6m of exclusive breastfeeding.

Conclusions: Improved ambient particulate matter benefits in decreasing childhood asthma prevalence. We firstly reported the finding of SEW to particulate matter at or closely after weaning on childhood asthma.