Wildfires are increasingly severe and frequent, posing health risks due to inhalation of wind-resuspended particulate matter <2.5 µm (PM2.5) from soils. These small, toxic particles can cause respiratory and cardiovascular diseases. This study aims to determine the relationship between the size distribution of airborne PMs and their associated toxic metal composition. Serpentine soil with high metal concentrations was collected and burned for two hours. Unburned and burned samples were resuspended in a closed wind box using two fans. Airborne particles were collected using four air samplers equipped with an impactor separating particles in five size ranges (from 2.5 μm to <0.25 μm) on preweighed filters. After two hours, the filters were removed and weighed to measure their masses. The filters were digested and analyzed using inductively coupled plasma mass spectroscopy (ICP-MS) to measure metal concentration. The results show that over 500 µg of particles were collected, almost evenly distributed across each size range. High concentrations of metals such as Fe, Cr, Ni, and Mn were found, with most Fe and Cr in particles <0.25 µm for both burnt and unburnt samples. Thus, the health risks associated with exposure to varying PM2.5 are potentially more nuanced compared to previous considerations. These findings contribute to understanding PM2.5 health threats and support the development of risk reduction strategies for vulnerable communities.

Windbox apparatus in which I collected soil particles separated by size

Presentation of my poster at the Stanford University SURGE symposium

Scott Fendorf

Stanford University

Appearances