Short-Term Associations between PM₁₀ and Respiratory Health Effects in Visby, Sweden

The old Swedish city Visby, located on the island Gotland, has, for several years, reported higher PM10 concentrations than any other city in Sweden. In Visby, local limestone is used, both in road paving and as sand used for anti-slip measures, resulting in a clear annual pattern of PM10 with the highest concentrations during winter/spring when studded tires are allowed. This study analyzes the short-term associations between PM10 and daily number of patients with acute respiratory problems (ICD-10 diagnoses: J00-J99) seeking care at the hospital or primary healthcare units in Visby during the period of 2013-2019. The daily mean of PM(10 )was on average 45 mu g m(-3) during winter/spring and 18 mu g m(-3) during summer/autumn. Four outcome categories were analyzed using quasi-Poisson regression models, stratifying for period and adjusting for calendar variables and weather. An increase in respiratory visits was associated with increasing concentrations in PM(10 )during the summer/autumn period, most prominent among children, where asthma visits increased by 5% (95% CI: 2-9%) per 10 mu g m(-3) increase in PM10. For the winter/spring period, no significant effects were observed, except for the diagnose group 'upper airways' in adults, where respiratory visits increased by 1% (95% CI: 0.1-1.9%) per 10 mu g m(-3) increase. According to the results, limestone in particles seem to be relatively harmless at the exposure concentrations observed in Visby, and this is in line with the results from a few experimental and occupational studies.