The total partitioning capacity of indoor surface reservoirs determines the mechanism by which humans receive nondietary exposure to organic contam...

Many types of air cleaners can generate small amounts of air pollution. Until now, there was no standard way to measure these negative by-products

This study evaluates the efforts of Oregon’s largest school district to improve indoor air quality and mitigate airborne disease transmission in the w…

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.

Far ultraviolet-C (UVC) light, especially germicidal UV light at 222 nm (GUV222), has received considerable attention for its potential to deactivate airborne pathogens indoors and prevent the spread of infectious disease. However, GUV222 also generates ozone (O3), posing human health risks and initiating additional photochemistry that may degrade indoor air quality. Air cleaners present an opportunity to counteract the drawbacks of GUV222 by removing harmful byproducts; however, to our knowledge, this has never been demonstrated. Here, we conduct laboratory experiments in a 7.5 m3 Teflon chamber using two commercially available air cleaners─a manganese-oxide-catalyst “ozone cleaner” and an activated-carbon-HEPA “volatile organic compound (VOC) + particulate matter (PM) cleaner”─each simultaneously with a GUV222 lamp. We show that both cleaner types remove a wide range of key pollutants, including O3, NO2, formaldehyde, VOCs, and particles. Application of chamber results to a photochemical model simulating chemistry in a 150 m3 room suggests that a single cleaner can achieve modest reductions in O3 levels and substantial reductions in secondary pollutant levels within typical indoor environments. These results indicate that indoor air pollutants from GUV222 can be mitigated through the use of air cleaning technology, thereby improving indoor air quality while maximizing the potential benefit of germicidal UV for human health.

Ozone (O3) is a major global air pollutant. Recent epidemiological studies have suggested links between O3 exposure and outbreaks of infectious diseases. However, whether environmentally relevant leve...

YouTube video by National Institute of Standards and Technology

This study evaluates the efforts of Oregon’s largest school district to improve indoor air quality and mitigate airborne disease transmission in the w…