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Annual average radon concentrations in California residences
K S Liu1, S B Hayward, J R Girman
1California Department of Health Services, Berkeley.
Journal of the Air & Waste Management Association
|September 1, 1991
Summary
California homes show an average indoor radon concentration of 0.85 pCi/l, with 0.8% of residences exceeding 4 pCi/l. High radon risk areas include the Sierra Nevada and Central Valley.
Area of Science:
- Environmental Health
- Radiological Protection
- Geospatial Risk Assessment
Background:
- Radon is a naturally occurring radioactive gas and a leading cause of lung cancer.
- Understanding indoor radon concentrations is crucial for public health risk assessment.
- California's diverse geology may influence indoor radon levels in residences.
Purpose of the Study:
- To determine annual average radon concentrations in California residences.
- To estimate the population fraction exposed to radon levels ≥ 4 pCi/l.
- To identify geographic regions with elevated radon risk within California.
Main Methods:
- Utilized passive (alpha track) samplers mailed to 310 residences.
- Home occupants deployed samplers and completed building/occupant characteristic questionnaires.
- Analyzed radon concentrations and correlated with geological zones.
Main Results:
- Measured radon concentrations ranged from 0.10 to 16 pCi/l (geometric mean: 0.85 pCi/l).
- Estimated 88,000 (0.8%) California residences exceed 4 pCi/l.
- Significant differences in radon levels found across geological zones; Sierra Nevada, eastern valleys, Central Valley, and Ventura/Santa Barbara counties showed higher means.
Conclusions:
- A small but significant fraction of California homes exceed the action level for radon.
- Geological factors significantly influence indoor radon concentrations across the state.
- Specific regions, including the Sierra Nevada and Central Valley, require focused radon mitigation and public awareness efforts.