# Evolving relationships between air pollution attenuation and AECOPD hospitalizations during a stringent control period in Shijiazhuang, China, 2017–2024

## TL;DR

This study shows that air pollution control in Shijiazhuang led to fewer hospitalizations for chronic obstructive pulmonary disease and weaker links between pollution and health.

## Contribution

The study reveals how stringent air pollution control reduces AECOPD hospitalizations and weakens pollutant-health associations over time.

## Key findings

- PM2.5, PM10, and SO2 concentrations decreased by 46%, 68%, and 85% during 2017–2024.
- PM2.5-attributable excess cases under WHO standards dropped by 37.1%.
- The relative risk between pollutants and AECOPD hospitalizations significantly attenuated over time.

## Abstract

Shijiazhuang, a typical industrial city, faced severe air pollution that elevated AECOPD risk. The period 2017–2024 coincided with stringent air pollution control, providing a key window to examine the evolving relationship between air quality improvements and AECOPD hospitalizations.

We analyzed 57,782 AECOPD hospitalizations (2017–2024) and air pollution data using a generalized additive Poisson time-series model. The analysis incorporated distributed lag non-linear terms while adjusting for meteorological conditions, seasonal trends, and day-of-week effects, with sensitivity analyses confirming result reliability.

PM2.5, PM10, and SO2 concentrations fell by 46%, 68%, and 85%, respectively. PM2.5-attributable excess cases under WHO standards dropped by 37.1%. Crucially, the association strength (relative risk) between most pollutants and hospitalizations showed a significant attenuating trend over time.

During this stringent air pollution control period in Shijiazhuang, marked air quality improvements were associated with reduced AECOPD hospitalizations and attenuated pollutant-health associations. Persistent ozone pollution highlights the need for coordinated VOC-NOx management.