- Abstract Dust storms are a common phenomenon, with significant impact on air pollution. Quantitative information on the influence of dust storms on particulate matter (PM) in the indoor environment is still lacking. Real-time PM 10 and PM 2.5 levels were measured simultaneously in outdoor and indoor air during dust events. A two-step multivariate analysis revealed factors controlling the PM levels. The results showed that during dust events average outdoor concentrations for PM 10 and PM 2.5 may reach 551 μg m −3 and 299 μg m −3 , respectively. Indoor PM 10 and PM 2.5 levels may reach concentrations of 517 μg m −3 and 282 μg m −3 , respectively. The analysis revealed a significant contribution of dust events to the indoor PM levels. The decreased in PM 2.5 /PM 10 ratio in both environments during dust storms, indicating on 82% infiltration of the PM 2.5 fraction into houses. The results serve to improve our understanding of dust storm, which may have implications for air quality and health issues.