Causal Effect of Air Pollution on Outpatient Visits for Chronic Rhinitis

Area of Science:

• Environmental Health
• Epidemiology
• Public Health

Background:

• The association between air pollution and chronic rhinitis is known, but causal links remain unclear.
• Previous studies often lack robust causal inference methods.
• Understanding the direct impact of air quality on rhinitis is crucial for public health interventions.

Purpose of the Study:

• To establish a causal relationship between the Air Quality Index (AQI) and outpatient visits for chronic rhinitis.
• To utilize instrumental variable (IV) analysis with thermal inversion as an instrument to overcome confounding factors.
• To quantify the short-term causal effect of air pollution on chronic rhinitis exacerbations.

Main Methods:

• Analysis of a large dataset of 81,210,447 outpatient visits for chronic rhinitis from 2014-2017.
• Application of a two-stage generalized method-of-moments Poisson regression model for IV analysis.
• Conducted stratified analyses by age and employed negative control methods to validate the instrumental variable approach.

Main Results:

• A significant causal relationship was found between increased AQI and outpatient visits for chronic rhinitis.
• The strongest effect was observed on lag day 0 (RR 1.078), with significant effects on lag days 3, 5, and 6.
• Adolescents aged 10-19 years showed the highest vulnerability to air pollution, with significant relative risks across all lag days.

Conclusions:

• This study provides robust evidence of a causal link between air pollution and increased healthcare utilization for chronic rhinitis.
• The findings highlight the direct disease burden attributable to air quality, beyond mere association.
• Public health strategies should consider the causal impact of air pollution on chronic rhinitis management.