Abstract
Exposure to radioactivity inside homes potentially poses severe health risks which can be exacerbated by the interaction between radioactive particles and fine indoor particles; in particular, the presence of α particles are a key risk factor. Hence, in this study, particle radioactivity was concurrently measured in the family rooms and basements of 26 homes to assess its concentrations and identify its sources, both indoors and outdoors, across two seasons. The levels of radon, air ions, and particle radioactivity, which included short- and long-lived α-activity (SLA and LLA, respectively), varied greatly but were substantially higher in the basements. Also, particle radioactivity—as well as PM2.5 and sulfur concentrations—were lower during the heating season. SLA was associated with radon, which was consistently of indoor origin, whereas LLA was more strongly related to the sulfur measured in indoor PM2.5, which is a proxy of outdoor infiltration. A regression model adjusted for sulfur and SLA also indicated a predominance of outdoor sources, likely due to the short residence time of indoor particles. Our results suggest that radiation in homes originates from both the decay of indoor radon and the infiltration of outdoor radioactivity.
Highlights
Indoor air pollution is an important contributor to the global burden of disease (WHO, 2007)
SLA was associated with radon, which was consistently of indoor origin, whereas LLA was more strongly related to the sulfur measured in indoor PM2.5, which is a proxy of outdoor infiltration
Indoor exposure to radon and α particles, which commonly occurs in residences, warrants great concern because of its potential health risks, which are increased by the presence of fine particles, as this fraction can be deeply inhaled
Summary
Indoor air pollution is an important contributor to the global burden of disease (WHO, 2007). Indoor air may contain a large spectrum of pollutants of indoor and outdoor origin including naturally occurring radon. Radon is a noble gas with a half-life of 3.8 days that originates from rocks and soils and tends to concentrate in enclosed spaces such as underground mines or inside houses, the basement. Radon is chemically inert and is rapidly inhaled and exhaled, whereas its progeny deposits onto lung airways. Two of its short-lived progeny (218Po and 214Po) and a long-lived progeny (210Po) emit α radiation, which damages airway lining cells and increases cancer risk (U.S EPA, 2003; WHO, 2009). Radon and its progeny are the most important source of ionizing radiation in the indoor environment.
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