Oxidative Potential from Common Indoor Sources of Particulate Matter

Area of Science:

• Environmental Health
• Air Quality Science
• Toxicology

Background:

• Most human exposure to particulate matter (PM) occurs indoors.
• The oxidative potential (OP) of indoor PM emissions and their health implications are not well understood.

Purpose of the Study:

• To quantify the oxidative potential (OP) of PM from common indoor sources.
• To compare the OP of indoor emissions to ambient PM2.5.
• To assess potential indoor exposure risks.

Main Methods:

• Measured OP using dithiothreitol (OP_DTT), glutathione consumption (OP_GSH), and hydroxyl radical generation (OP_OH) assays.
• Quantified mass-normalized OP (OP^m) for various indoor sources.
• Conducted an exploratory exposure assessment in a model apartment.

Main Results:

• Intrinsic OP^m of indoor sources (candles, incense, cigarettes, humidifiers, toasters, air fryers) was comparable or higher than ambient PM_2.5.
• Candle emissions (with draft) showed highest OP_DTT^m and OP_OH^m; cigarette emissions had highest OP_GSH^m.
• Certain indoor sources could lead to higher OP exposure within an hour than a full day of ambient PM_2.5 exposure.

Conclusions:

• Indoor emissions significantly contribute to oxidative potential exposure.
• Elemental carbon and metals are key drivers of OP in combustion and non-combustion sources, respectively.
• Urgent need for health impact assessments and policy development to mitigate indoor PM exposure risks.