Atmospheric Concentration of Particulate Matters Associated with Increased Inpatient and Outpatient Visits for Chronic Respiratory Diseases in Xiamen, China
Air pollution, particularly exposure to airborne particulate matter such as fine particulate matter (PM2.5) and inhalable particulate matter (PM10), has been increasingly recognized as a significant environmental risk factor for chronic respiratory diseases. These pollutants are known to cause acute exacerbations of conditions such as bronchitis, emphysema, chronic obstructive pulmonary disease (COPD), and bronchiectasis, leading to increased healthcare utilization and even mortality in severe cases. This study investigates the association between atmospheric concentrations of PM2.5, PM10, and ozone (O3), along with weather conditions, and the frequency of inpatient and outpatient visits for chronic respiratory diseases in Xiamen, China.
The research was conducted using data from the Xiamen Health and Medical Big Data Center, covering the period from January 1, 2017, to December 31, 2019. The study focused on chronic respiratory diseases classified under the International Classification of Diseases Tenth Revision (ICD-10) codes J40, J41, J42, J43, J44, and J47, which include bronchitis, emphysema, COPD, and bronchiectasis. The data were further stratified by age groups: 0–19 years, 20–39 years, and ≥40 years. Daily concentrations of air pollutants (PM2.5, PM10, and O3) were obtained from the Ministry of Ecology and Environment, while weather data, including average temperature and wind speed, were sourced from the TianQiHouBao website.
The study employed a univariate Poisson regression model to assess the effects of air pollutants on healthcare visits for chronic respiratory diseases. The analysis accounted for the lag effects of pollutant exposure, evaluating the impact over a period of 0 to 14 days. The results were reported based on the highest effect size observed within this lag period. The statistical analysis was conducted using R software, with a significance threshold set at a two-sided P value of 0.05.
The dataset included 238,455 outpatient visits and 8,113 inpatient visits for chronic respiratory diseases during the study period. Among these, the majority of patients were male, with males accounting for 54.15% of outpatients and 73.97% of inpatients. The average age of outpatients was 55 years, while inpatients were older, with an average age of 66 years. The most common diagnosis among inpatients was COPD (64.25%), followed by bronchiectasis (26.39%). Among outpatients, acute or chronic bronchitis was the predominant diagnosis, accounting for 87.28% of visits.
From 2017 to 2019, there was a notable increase in both inpatient and outpatient visits for all three disease groups: bronchitis (J40–J42) increased by 68.22%, emphysema and COPD (J43–J44) by 35.92%, and bronchiectasis (J47) by 33.93%. The average daily number of inpatient visits was 11.81, while outpatient visits averaged 452.02 per day. During the same period, the daily average concentration of PM2.5 in Xiamen ranged from 4 to 100 µg/m³, PM10 ranged from 9 to 138 µg/m³, and O3 ranged from 0 to 172 µg/m³. Weather conditions varied, with average daily temperatures ranging from 7°C to 32.5°C and wind speeds ranging from 1.5 to 6.5 on the Beaufort scale.
The study found significant associations between air pollutant concentrations and healthcare visits for chronic respiratory diseases. An interquartile range (IQR) increase in PM2.5 concentration was associated with a 13.71% increase in inpatient visits for emphysema and COPD among patients aged 40 years and older, with the strongest effect observed 14 days post-exposure. Similarly, an IQR increase in PM10 concentration was linked to a 16.91% increase in inpatient visits for bronchitis among patients aged 0–19 years and a 7.76% increase in inpatient visits for emphysema and COPD among patients aged ≥40 years. In contrast, an IQR increase in O3 concentration was associated with a 12.35% decrease in inpatient visits for bronchitis among patients aged 0–19 years, a 10.33% decrease for emphysema and COPD, and a 10.32% decrease for bronchiectasis among patients aged ≥40 years.
For outpatient visits, the study also identified significant associations with air pollutants. An IQR increase in PM2.5 concentration was associated with a 7.04% increase in outpatient visits for bronchitis among patients aged 0–19 years, a 7.51% increase among patients aged 20–39 years, and a 16.61% increase among patients aged ≥40 years. Similarly, an IQR increase in PM10 concentration was linked to a 7.73% increase in outpatient visits for bronchitis among patients aged 0–19 years and a 10.06% increase among patients aged ≥40 years. O3 exposure was also associated with increased outpatient visits, with a 6.33% increase for bronchitis among patients aged 0–19 years, a 32.76% increase for emphysema and COPD among patients aged 0–19 years, and a 4.20% increase for bronchiectasis among patients aged 20–39 years.
Weather conditions were also found to influence healthcare visits for chronic respiratory diseases. An IQR increase in average daily temperature was associated with reduced outpatient and inpatient visits for bronchitis, with a 32.45% decrease among outpatients aged ≥40 years and a 48.05% decrease among inpatients aged 20–39 years. Conversely, an IQR increase in wind speed was associated with increased outpatient and inpatient visits for bronchitis, with a 19.69% increase among outpatients aged 0–19 years and a 65.83% increase among inpatients aged 20–39 years.
The study also explored the role of weather conditions as instruments for air pollutants. Wind speed was found to influence inpatient visits for bronchiectasis among patients aged ≥40 years, likely through its impact on O3 concentration. Similarly, temperature influenced outpatient visits for emphysema and COPD among patients aged 20–39 years and bronchiectasis among patients aged 0–19 years, likely by altering PM2.5 concentration.
The findings of this study are consistent with prior research demonstrating the adverse effects of particulate matter on respiratory health. PM2.5 and PM10 are known to induce and exacerbate airway and lung inflammation, leading to acute exacerbations of chronic respiratory diseases. The study also highlights the complex interplay between air pollutants and weather conditions, which can further modulate the impact of pollutants on respiratory health.
In conclusion, this study provides robust evidence of the association between air pollutants (PM2.5, PM10, and O3) and healthcare visits for chronic respiratory diseases in Xiamen, China. The findings underscore the need for public health policies aimed at reducing air pollution and improving the management of chronic respiratory diseases. By addressing the environmental factors contributing to respiratory health, it is possible to reduce the burden of these diseases and improve overall public health outcomes.
doi.org/10.1097/CM9.0000000000001435
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