Choong-Min Kang 1, Man Liu1, Eric Garshick2, Petros Koutrakis1

Exposure, Epidemiology, and Risk Program, Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA 02215, USA
Pulmonary, Allergy, Sleep, and Critical Care Medicine Section, Medical Service, VA Boston Healthcare System; Channing Division of Network Medicine, Brigham & Women’s Hospital; Harvard Medical School, Boston, MA 02130, USA

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Kang, C.M., Liu, M., Garshick, E. and Koutrakis, P. (2020). Indoor Particle Alpha Radioactivity Origins in Occupied Homes. Aerosol Air Qual. Res.,


  • Addressed the origins of Indoor radioactivity.
  • Short-lived α-activity is associated with indoor radon decay.
  • Long-lived α-activity is mainly associated with outdoor radioactivity.


Particle radioactivity was measured to assess indoor radioactive levels and its origins that are required to be estimated for accurate risk assessment. Indoor exposure to home radioactivity can cause severe health risks, which can be accelerated through interaction with indoor fine particles. Particularly α particle is the key to induce this risk. Concurrent measurements in family rooms and basements were conducted in 26 homes to evaluate indoor and outdoor origins contributing to indoor radioactive exposure during two seasons. Radon, air ions, and particle radioactivity that included short- (SLA) and long-lived α-activity (LLA) were substantially higher in basements and varied greatly. Particle radioactivity along with PM2.5 and sulfur were higher for the non-heating season. SLA was associated with radon, consistent an indoor origin, whereas LLA was more strongly associated with sulfur measured in indoor PM2.5 as a proxy of outdoor infiltration. A multi-regression model adjusted with sulfur and SLA also indicates predominant outdoor origin, likely due to the short residence time of indoor particles. Our results suggest that indoor exposures to radiation are as a result of the decay of indoor radon and the infiltration of outdoor radioactivity, both of which may contribute to potential health risks from indoor particle radioactivity.

Keywords: Radioactivity origin; Radon; Particle radioactivity; Short-lived α-activity; Long-lived α-activity

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