The hospital admission risk and burden of acute appendicitis due to fine particulate matter pollution: Nationwide evidence from China

Acute appendicitis (AA) is a predominant surgical emergency, yet its environmental risk factors remain poorly understood. While fine particulate matter (PM_2.5) is a known risk factor for cardiopulmonary disease, its association with AA morbidity has not been well established. We conducted a nationwide time-stratified case-crossover study using hospital admission (HA) records of AA across 277 Chinese cities of prefecture level or above. The air pollutants studied were PM_2.5 and its major constituents. We applied conditional logistic regression model and distributed lag non-linear model to estimate the exposure- and lag-response associations. During the study period (2013–2017), 1,287,040 HAs of AA were recorded. We observed that the impact of PM_2.5 and its major constituents on the risk of HAs for AA emerged within 1–2 days after exposure and persisted for up to 7 days. Specifically, each interquartile range (30.99 μg/m³) increase in PM_2.5 over lag 0–7 was associated with a 2.10% (95% CI: 1.02%, 3.19%) higher risk of HAs for AA. We found that black carbon (BC) was linked to the highest (2.44%, 95%CI: 1.31%, 3.58%) association with HAs for AA among the major PM_2.5 constituents. The attributable fractions of AA due to BC and PM_2.5 were 2.99% (95%CI: 1.64%, 4.32%) and 2.23% (95%CI:1.10%, 3.34%), respectively. This study provides nationwide evidence on the HA risk and burden of AA associated with PM_2.5 and its major constituents. Our findings underscore the hazardous impact of PM_2.5 on gastrointestinal health and the need for effective air quality control.