Association between PM_2.5-bound metals and pediatric respiratory health in Guangzhou: An ecological study investigating source, health risk, and effect

Background: The adverse effects of 2.5-μm particulate matter (PM_2.5) exposure on public health have become an increasing concern worldwide. However, epidemiological findings on the effects of PM_2.5-bound metals on children's respiratory health are limited and inconsistent because PM_2.5 is a complicated mixture.

Objectives: Given the vulnerability of children's respiratory system, aim to pediatric respiratory health, this study evaluated the potential sources, health risks, and acute health effects of ambient PM_2.5-bound metals among children in Guangzhou, China from January 2017 to December 2019.

Methods: Potential sources of PM_2.5-bound metals were detected using positive matrix factorization (PMF). A health risk assessment was conducted to investigate the inhalation risk of PM_2.5-bound metals in children. The associations between PM_2.5-bound metals and pediatric respiratory outpatient visits were examined with a quasi-Poisson generalized additive model (GAM).

Results: During 2017-2019, the daily mean concentrations of PM_2.5 was 53.39 μg/m³, and the daily mean concentrations of PM_2.5-bound metals range 0.03 ng/m³ [thorium (Th) and beryllium (Be)] from to 396.40 ng/m³ [iron (Fe)]. PM_2.5-bound metals were mainly contributed by motor vehicles and street dust. PM_2.5-bound arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr)(VI), nickel (Ni), and lead (Pb) were found to pose a carcinogenic risk (CR). A quasi-Poisson GAM was constructed that showed there were significant associations between PM_2.5 concentrations and pediatric outpatient visits for respiratory diseases. PM_2.5 was significantly associated with pediatric outpatient visits for respiratory diseases. Moreover, with a 10 μg/m³ increase in Ni, Cr(VI), Ni, and As concentrations, the corresponding pediatric outpatient visits for respiratory diseases increased by 2.89% (95% CI: 2.28-3.50%), acute upper respiratory infections (AURIs) increased by 2.74% (2.13-3.35%), influenza and pneumonia (FLU&PN) increased by 23.36% (20.09-26.72%), and acute lower respiratory infections (ALRIs) increased by 16.86% (15.16-18.60%), respectively.

Conclusions: Our findings showed that PM_2.5 and PM_2.5-bound As, Cd, Co, Cr(VI), Ni, and Pb had adverse effects on pediatric respiratory health during the study period. New strategies are required to decrease the production of PM_2.5 and PM_2.5-bound metals by motor vehicles and to reduce levels of street dust to reduce children's exposure to these pollutants and thereby increase child health.