SO-002

Air pollution has been associated with adverse cardiovascular effects in adults, but its impact on children's heart rate variability (HRV) is unclear.

We conducted two longitudinal panel studies among 271 children aged 4-13 years and each with up to three repeated visits over three distinct seasons within one year. Each visit occurred in a separate season. Personal real-time PM_2.5 exposure was measured 72-h preceding each HRV assessment. Residential NO₂ and O₃ levels were estimated using random forest modeling, while SO₂ and CO were from the China High Air Pollutants. Linear mixed-effects, bayesian kernel machine regression (BKMR) and weighted quantile sum (WQS) regression were employed to assess the association between air pollution and HRV.

The strongest inversely dose-response associations emerged for O₃ with root mean square of successive differences in adjacent NN intervals (RMSSD), low-frequency power and high-frequency power (HF), and NO₂ with HF at lag 0 (physical examination day). Even when O₃ was below Chinese Ambient Air Quality Standard Grade I (CAAQS I) (<100 μg/m³), its adverse association with HRV remained significant. BKMR and WQS indicated that co-exposure to PM_2.5, NO₂, O₃, SO₂ and CO was associated with decreased RMSSD and HF, with O₃ contributing the most. Each quartile increase in the mixture was related to RMSSD and HF decreasedby 2.82 % (95 % CI: 0.73 %, 4.90 %) and 5.84 % (95 % CI: 0.85 %, 9.61 %), respectively. Additionally, the detrimental effect of O₃ on HF was stronger in children with PM_2.5 levels exceeding CAAQS I (≥35 μg/m³) and overweight/obesity.

Short-term air pollution exposure showed dose-response associations with decreased pediatric HRV, with O₃ and NO₂ as key contributors.

Recent studies have shown a close correlation between air pollution and the occurrence of asthma. A distributed lag nonlinear model was used in this research to analyze the relationship between 58,610 asthma outpatient hospital visits and daily PM_2.5, PM₁₀, NO₂, SO₂, CO, and eight hour mean O₃ exposure from 4 hospitals in Xinxiang City, Henan province from January 1, 2016 to December 31, 2021, and a stratified analysis of gender and age were conducted. Results showed that low concentrations of daily PM_2.5 (40 µg/m³), PM₁₀ (20 and 80 µg/m³), CO (0.8 mg/m³), NO₂ (10-30 µg/m³) and SO₂ (15 µg/m³) exposure reduced the number of outpatient visits for asthma patients. High levels of daily PM_2.5 (50-100 µg/m³), PM₁₀ (100-140 and 820 µg/m³), and SO₂ (20-25 µg/m³) exposure increased the number of outpatient visits for asthma patients. Both low (15-60 µg/m³) and high (150-205 µg/m³) concentrations of the eight hour mean O₃ exposure increased asthma outpatient hospital visits. Gender-stratified analysis revealed that, for male asthma patients, the daily outpatient visits decreased when CO exposure concentration of 0.8 mg/m³; while for female asthma patients, the daily outpatient visits decreased when SO₂ exposure concentration of 15 µg/m³, but increased when the concentration was 20 µg/m³. In comparison, both low and high concentrations of eight hour mean O₃ exposure increased the daily male asthma outpatient hospital visits. Additionally, when the eight hour mean O₃ exposure concentration was 10-30 µg/m³ and the daily SO₂ exposure concentration was 20 µg/m³, asthma outpatient hospital visits for adult increased; when the eight hour mean O₃ exposure concentration was 145-220 µg/m³ and the daily SO₂ exposure concentration was 50-110 µg/m³, asthma outpatient hospital visits for adolescent increased. This study suggests that asthma patients should limit going outdoors on days with poor air quality, especially for women and adolescents.