Refining particulate matter classification : addressing health risks of smaller fractions

Particulate matter (PM) is a significant global health risk, with existing regulations primarily focusing on PM10 and PM2.5. However, smaller particles, such as PM1 and PM0.1, which penetrate deeper into the body, remain largely unregulated. This study introduces a refined PM classification system based on health impact, filter efficiency, and building penetration. The findings highlight that particles under 1 μm, especially those in the 200-250 nm range, pose the greatest challenges in terms of health impact, filtration and building penetration. The study proposes a ten-bin classification for PM sizes (0.01–10 μm), allowing for a more detailed assessment of health risks and improving mitigation strategies. By adjusting guideline values based on current regulations, this new system could better inform policy development and regulatory frameworks, ultimately enhancing public health protection.