Ultrafine particles (UFP) are implicated in morbidity (oxidative stress) and mortality (cardiorespiratory disease). They are so tiny (<100 nm in diameter) that they can evade cell defenses and perhaps can bypass the blood-brain barrier. Unlike larger particles (PM2.5, PM10) they are not monitored regularly in outdoor air. This has left a gap in our knowledge of outdoor concentrations and the major outdoor sources.
A similar gap exists in our knowledge of indoor concentrations and sources. Recent studies suggest that cooking, whether on gas or electric stoves, may be the major indoor source for most people. In this presentation, the basic findings of the influence of cooking will be reviewed in detail, including a surprising discovery about the size distribution of cooking aerosols.
Total indoor exposure depends on both indoor sources and outdoor infiltration. The crucial parameter is the infiltration factor. Results suggest that whereas PM2.5 and PM10 may have typical infiltration factors near 0.5 (50% of the particle concentration in outdoor air will be airborne indoors at equilibrium), the equivalent value for UFP may be closer to 0.25. This downweights the importance of outdoor air for personal exposure, and thus makes indoor air sources and mitigation techniques for UFP relatively more important than for PM in general. For example, we will explore filtration and kitchen exhaust fans as possible remedies.
A recording of this seminar is available at: https://vimeo.com/70866529