Year-to-year variations in annual average indoor 222Rn concentrations

Area of Science:

• Environmental Science
• Radiological Health
• Indoor Air Quality

Background:

• Indoor radon (222Rn) is a significant contributor to public radiation exposure.
• Understanding year-to-year variations in indoor radon is crucial for accurate risk assessment and public health strategies.
• Grand Junction, Colorado, has been a focus for radon research due to its geological characteristics.

Purpose of the Study:

• To quantify the year-to-year variability of indoor radon concentrations in residential environments.
• To assess the reliability of alpha-track monitors (ATM) for long-term radon monitoring.
• To determine the actual variability of radon levels independent of measurement device fluctuations.

Main Methods:

• Annual average indoor 222Rn concentrations were measured in 40 residences near Grand Junction, CO.
• Commercial alpha-track monitors (ATM) were deployed for consecutive 12-month periods over a 6-year timeframe.
• Statistical analysis, including coefficient of variation, was used to evaluate measurement variability and true radon concentration changes.

Main Results:

• A mean coefficient of variation of 25% was observed for year-to-year radon concentration variability across 25 sampling stations with complete data.
• Individual station variability ranged from 7.7% to 51%, indicating diverse patterns across different homes.
• After correcting for detector response variability, the actual year-to-year variability in indoor radon concentrations was estimated at approximately 22%.

Conclusions:

• Indoor radon concentrations exhibit moderate year-to-year variability in residential settings.
• Alpha-track monitors provide reliable data, but their response variability must be considered in long-term studies.
• The findings underscore the importance of repeated measurements for accurately characterizing indoor radon exposure over time.