Dustin Poppendieck (@poppendieck.bsky.social)

Indoor particle sources may be worse than outdoor sources. More data showing ill effects from candles, incense, cigarettes, toasters, air fryers and humidifiers using tap water: pubs.acs.org/doi/full/10....

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Oxidative Potential from Common Indoor Sources of Particulate Matter Although people spend nearly 90% of their time indoors, the source-specific oxidative potential (OP) from indoor emissions spanning multiple particle generation mechanisms is largely unknown. Here, we quantify the OP of the PM originating from commonly used indoor sources via three different assays, i.e., dithiothreitol consumption (OPDTT), glutathione consumption (OPGSH), and hydroxyl radical generation (OPOH). The intrinsic (mass-normalized) OPm of several sources (candles, incense, cigarettes, humidifiers using tap water, toasters, and air fryers) were comparable (0.75–1.25×) or exceeded (1–6×) that of typical ambient PM2.5. Emissions from candles in the presence of a wind-draft had the highest OPDTTm and OPOHm while OPGSHm was highest for cigarette emissions. Elemental carbon determined the OP of PM emitted from sources undergoing incomplete combustion, whereas, for noncombustion sources (water evaporation and heating-based), metals were the important drivers. An exploratory exposure assessment in a hypothetical apartment (volume = 100 m3, air change rate = 0.45 h–1, and penetration coefficient = 0.6) revealed that certain sources (e.g., incense, cigarettes, toasters, and air-fryers) could result in occupants being exposed to higher OP in less than 1 h of indoor operation than that resulting from inhaling typical U.S. ambient PM2.5 (8 μg/m3) over an entire day. Collectively, these results demonstrate the importance of indoor emissions, emphasizing the need for more comprehensive health impact assessments to assist in the development of policy recommendations aimed at mitigating indoor PM exposure. https://pubs.acs.org/doi/full/10.1021/acs.est.5c01696