Research from the Institute of Environmental Medicine (IMM), Karolinska Institutet shows that air pollution and traffic noise together may pose a greater risk for stroke than either factor alone. The researchers found that even at low levels - below the EU's air quality standards and around WHO noise recommendation levels- the risk of stroke increased significantly.
The study, published in Environmental International, analyzed data from 136,897 adults in Sweden, Denmark, and Finland. The results show that a 5 µg/m³ increase in air pollution (PM2.5) raises the risk of stroke by 9 %, while an 11 dB increase in traffic noise increases the risk by 6 %. When both factors are combined, the risk may be even higher. For example, in quieter areas (40 dB), an increase in PM2.5 was linked to a 6% rise in stroke risk, but in noisier areas (80 dB), the same increase in PM2.5 raised the risk by 11%, though this result was not statistically significant.
- Research on the combined effects of air pollution and traffic noise is still scarce, and our study provides important new insights. The fact that we see clear associations even at relatively low levels indicates that current exposure limits may not be sufficient to protect public health. Stronger regulations are needed to reduce exposure and lower the risk of stroke and other diseases, say Huyen Nguyen Thi Khanh and Jeroen de Bont, authors of the paper.
The findings can also help policymakers allocate resources more effectively. By targeting areas where people are exposed to both high levels of air pollution and noise, authorities can significantly reduce stroke incidence and improve public health.
The researchers now plan to study how changing residence to areas with higher or lower exposure to air pollution and noise affects cardiovascular risk, as well as how air pollution interacts with other urban factors to influence cardiovascular diseases.
Publication:
Thi Khanh HN, Stafoggia M, Sørensen M, Poulsen AH, Raaschou-Nielsen O, Khan J, Brandt J, Olsen A, Andersen ZJ, Simonsen MK, Lim YH, Zhang J, Cole-Hunter T, Pershagen G, Pyko A, Åkesson A, Stockfelt L, Andersson EM, Ögren M, Segersson D, Rosengren A, Oudin A, Albin M, Engström G, Gustafsson S, Mattisson K, Rizzuto D, Magnusson PK, Gudjonsdottir H, Leander K, Lanki T, Tiittanen P, Yli-Tuomi T, Jousilahti P, Ljungman P, de Bont J
Environ Int 2025 Mar;198():109403
