Adequacy of stationary measurements as proxies for residential personal exposure to gaseous and particle air pollutants.

People are exposed to myriad of airborne pollutants in their homes. Owing to diverse potential sources of air pollution and human activity patterns, accurate assessment of residential exposures is complex. In this study, we explored the relationship between personal and stationary air pollutant measurements in residences of 37 participants working from home during the heating season. Stationary environmental monitors (SEMs) were located in the bedroom, living room or home office and personal exposure monitors (PEMs) were worn by the participants. SEMs and PEMs included both real-time sensors and passive samplers. During three consecutive weekdays, continuous data were obtained for particle number concentration (size range 0.3-10 µm), carbon dioxide (CO2), and total volatile organic compounds (TVOC), while passive samplers collected integrated measures of 36 volatile organic compounds (VOCs) and semi volatile organic compounds (SVOCs). The personal cloud effect was detected in >80% of the participants for CO2 and >50% participants for PM10. Multiple linear regression analysis showed that a single CO2 monitor placed in the bedroom efficiently represented personal exposure to CO2 (R2 = 0.90) and moderately so for PM10 (R2 = 0.55). Adding a second or third sensor in a residence did not lead to improved exposure estimates for CO2, with only 6-9% improvement for particles. Selecting data from SEMs when participants were in the same room improved personal exposure estimates by 33% for CO2 and 5% for particles. Out of 36 detected VOCs and SVOCs, 13 had at least 50% higher concentrations in personal versus stationary samples. Findings from this study aid improved understanding of the complex dynamics of gaseous and particle pollutants and their sources in residences, and could support the development of refined procedures for residential air quality monitoring and inhalation exposure assessment.

Longitudinal assessment of personal air pollution clouds in ten home and office environments.

Elevated exposure to indoor air pollution is associated with negative human health and well-being outcomes. Inhalation exposure studies commonly rely on stationary monitors in combination with human time-activity patterns; however, this method is susceptible to exposure misclassification. We tracked ten participants during five consecutive workdays with stationary air pollutant monitors at their homes and offices, and wearable personal monitors. Real-time measures of size-resolved particulate matter (within range 0.3-10 µm) and CO2 , and integrated samples of PM10 , VOCs, and aldehydes were collected. The PM10  cloud magnitude (excess of PM10 beyond stationary room concentration) was detected for all participants in homes and offices. The PM10  cloud magnitude ranged within 5-37 µg/m3 and was the most discernible in the coarse particle size fraction. Particles associated with "Urban mix," "Traffic," and "Human activities" sources contributed the most to PM10 exposures. The personal CO2  clouds were detected for participants with the SEMs in their living rooms and private or low-occupancy offices. The stationary monitors placed in bedrooms were better predictors of personal PM10 and CO2 exposures. An overall of 33 VOCs and aldehydes were detected in both microenvironments, with the majority exhibiting high correlation between personal and stationary stations.