Survey of residential indoor Particulate Matter measurements 1990-2019

Abstract

We surveyed literature on measurements of indoor particulate matter in all size fractions, in residential environments free of solid fuel combustion. Data from worldwide studies from 1990-2019 were assembled into the most comprehensive collection to date. Out of 2,752 publications retrieved, 538 articles from 433 research projects met inclusion criteria and reported unique data, from which more than 2,000 unique sets of indoor PM measurements were collected. Distributions of mean concentrations were compiled, weighted by study size. Long-term trends, the impact of non-smoking, air cleaners, and the influence of outdoor PM were also evaluated. Similar patterns of indoor PM distributions for North America and Europe could reflect similarities in the indoor environments of these regions. Greater observed variability for all regions of Asia may reflect greater heterogeneity in indoor conditions, but also low numbers of studies for some regions. Indoor PM concentrations of all size fractions were mostly stable over the survey period, with the exception of observed declines in PM2.5 in European and North American studies, and in PM10 in North America. While outdoor concentrations were correlated with indoor concentrations across studies, indoor concentrations had higher variability, illustrating a limitation of using outdoor measurements to approximate indoor PM exposures.Practical implicationsResidential indoor PM concentration ranges for several size fractions measured in different worldwide regions are provided and may inform future public health research and practice, including PM exposure and risk assessment, and evaluation of IAQ-related interventions and consumer products, such as portable air cleaners.This long-term indoor PM concentration record provides insights regarding the degree of change in observed indoor PM concentrations by world region and some of the factors contributing to increasing or decreasing temporal trends.Outdoor air pollution remains a major influence on indoor concentrations of PM of all sizes.Greater variability of indoor concentrations of PM relative to outdoor concentrations demonstrate the potential for exposure misclassification when using outdoor concentrations to estimate indoor exposures and risk.IAQ interventions, including removing environmental tobacco smoke or using filtration-based portable air cleaners, can produce major improvements in IAQ through reduced indoor particle concentrations.

Residential Indoor and Outdoor PM Measured Using Low-cost Monitors during the Heating Season in Monroe County, NY

“…Indoor particulate pollution can arise from multiple sources including the penetration of the ambient aerosol into indoor spaces (Chen and Zhao, 2021) and a variety of indoor particle sources such as cooking, cleaning, and indoor combustion sources (Isaxon et al, 2015). Ilacqua et al (2021) reviewed the literature on indoor/outdoor ratios for various particulate matter (PM) sizes. Liu and Zhang (2019) have extensively reviewed the literature on the relationships between outdoor and indoor PM2.5 concentrations and constituents and report that outdoor PM2.5 concentrations are generally higher than indoor values.…”