Road Dust, PM₁₀ Exposure and Respiratory Health in Visby: An Updated Analysis of Mitigation Efforts

Background: High concentrations of coarse particulate matter PM₁₀ from road dust are a major air quality concern in Visby, Sweden. To mitigate these levels, local authorities replaced soft limestone with crushed granite as an anti-slip material starting in the winter of 2023/2024. This is a follow-up study evaluating the impact of this intervention on PM₁₀ concentrations and the associated short-term respiratory health effects. Methods: Daily counts of healthcare visits for respiratory diseases (ICD-10: J00-J99) and daily mean PM₁₀ concentrations were analyzed using a quasi-Poisson regression model. This study compared the limestone period (2015-2019) with the granite period (2023-2025), stratified by season (winter/spring and summer/autumn) and age group (children 0-17 years and adults >17 years). Results: The transition to crushed granite reduced peak PM₁₀ concentrations during the spring. For adults, the relative risks for respiratory visits during winter/spring decreased during the granite period when compared to the limestone period (Wald p < 0.05). However, when considering that there were a majority of non-statistically significant differences when comparing the granite and limestone periods, these results should be interpreted with caution. Among children, more pronounced associations were observed during summer, although no significant differences in risk were detected between the limestone and granite periods. Conclusions: Although the intervention effectively lowered particle mass concentrations, only minor changes were observed in the overall epidemiological pattern. This suggests that public health improvements may be limited by factors beyond total mass reduction, such as particle mineralogy or seasonal exposure dynamics.