Exposure Assessment of Indoor PM Levels During Extreme Dust Episodes

Millions of people live in areas that are subject to frequent dust events; however gaps remain in our knowledge about the association between dust, air quality and corresponding particulate matter (PM) exposure levels inside buildings. This case study demonstrates how the PM_2.5 and PM₁₀ levels in an urban environment respond to strong natural dust episodes. Real-time measurements were recorded simultaneously in indoor and outdoor environments in households in the city of Beer-Sheva, Israel during several strong dust events. A typical strong event was used for a detailed analysis of PM₁₀ and PM_2.5. Outdoor daily concentrations were above 1000 µg m^-3 for PM₁₀, the maximum hourly value of which was 1320 µg m^-3. The indoor PM₁₀ peaked at about 700 µg m^-3 and fluctuated in parallel with the outdoor level but with a time lag of about 15 min. Indoor air tended to remain for several hours after the dust event had subsided. Analyses of multiple events revealed that the dependence of indoor PM_2.5 and PM₁₀ on natural dust varies but is not directly linked to the level of atmospheric dust concentration. From a health perspective, the exposure risk posed by extreme indoor PM_2.5 and PM₁₀ levels generated by natural dust episodes should be considered.