Ambient air pollution is associated with pediatric pneumonia: a time-stratified case-crossover study in an urban area.

Background: Pneumonia, the leading reason underlying childhood deaths, may be triggered or exacerbated by air pollution. To date, only a few studies have examined the association of air pollution with emergency department (ED) visits for pediatric pneumonia, with inconsistent results. Therefore, we aimed to elucidate the impact of short-term exposure to particulate matter (PM) and other air pollutants on the incidence of ED visits for pediatric pneumonia.
Methods: PM _2.5 , PM ₁₀ , and other air pollutant levels were measured at 11 air quality-monitoring stations in Kaohsiung City, Taiwan, between 2008 and 2014. Further, we extracted the medical records of non-trauma patients aged ≤17 years and who had visited an ED with the principal diagnosis of pneumonia. A time-stratified case-crossover study design was employed to determine the hazard effect of air pollution in a total of 4024 patients.
Results: The single-pollutant model suggested that per interquartile range increment in PM _2.5 , PM ₁₀ , nitrogen dioxide (NO ₂ ), and sulfur dioxide (SO ₂ ) on 3 days before the event increased the odds of pediatric pneumonia by 14.0% [95% confidence interval (CI), 5.1-23.8%], 10.9% (95% CI, 2.4-20.0%), 14.1% (95% CI, 5.0-24.1%), and 4.5% (95% CI, 0.8-8.4%), respectively. In two-pollutant models, PM _2.5 and NO ₂ were significant after adjusting for PM ₁₀ and SO ₂ . Subgroup analyses showed that older children (aged ≥4 years) were more susceptible to PM _2.5 (interaction p = 0.024) and children were more susceptible to NO ₂ during warm days (≥26.5 °C, interaction p = 0.011).
Conclusions: Short-term exposure to PM _2.5 and NO ₂ possibly plays an important role in pediatric pneumonia in Kaohsiung, Taiwan. Older children are more susceptible to PM _2.5 , and all children are more susceptible to NO ₂ during warm days.