Air pollution, including PM, as a potential risk factor for the development of appendicitis in Korea: a case-crossover study.

Interest in the association between particulate air pollution and appendicitis risk has been increasing in recent years, and previous studies have suggested a link between particulate matter ≤10 μm in diameter (PM) and appendicitis. However, robust evidence is currently lacking. This study explored the association between short-term PM exposure and appendicitis using data from Ewha Womans University Mokdong Hospital, Seoul, Korea, between January 1, 2001 and December 31, 2018. We employed a time-stratified case-crossover design using data from 6,526 appendicitis patients taken from the hospital's electronic medical records system. We analyzed the data using a conditional logistic regression model adjusted for daily mean temperature and relative humidity. The effect size of PM was estimated in terms of each 10 μm/m increase in PM concentration. Sex, season, and age group were analyzed as subgroups. Appendicitis patients had been exposed to higher levels of PM concentrations 3 days (OR 1.045, 95% CI : 1.007-1.084) and 7 days (OR, 1.053; 95% CI, 1.005-1.103) before hospital admission. The case-crossover analysis stratified by sex, age, and season showed that the male sex, being aged under 10, and the cold season were associated with a significantly stronger association between appendicitis and PM concentrations. Our study found that PM concentrations were associated with appendicitis in boys aged under 10. The cold season was also a risk factor. Further research with a larger sample size and with other pollutants is required to clarify the association between PM and appendicitis.