A Comparative Study of Radon Levels in Federal Buildings and Residential Homes in Canada

Evaluating radon concentration and temporal correction factors in residential and workplace buildings: A comparison of passive and active methods

Effective mitigation of the health impacts of radon exposure begins with accurate measurement of this environmental contaminant. Typically, radon surveys require measurements over a period of several months. This process involves the application of temporal correction factors (TCF). Disparities in indoor radon concentration (IRC) are evident across building types. While the integrated technique has traditionally been considered the most reliable for measuring IRC, the active method is becoming more prevalent due to the availability of commercial radon measurement instruments. The aim of this study is to compare IRC using passive (CR-39) and active (ICA device) methods across 69 indoor spaces, including 35 workplaces and 34 residential buildings. The investigation was conducted over a span of one year and included 966 CR-39 detectors that were replaced every 3 and 6 months, respectively, to assess seasonal fluctuations and facilitate the computation of TCF. Statistically significant differences in IRC were observed between residential and workplace buildings (p < 0.001). Among workplaces, educational and research institutions showed the highest average IRC (166 Bq/m3), while hospitals exhibited the lowest (25 Bq/m3). Significant differences in TCF were found between the two measurement methods (p < 0.05), making TCF specific to the passive method inapplicable to active method. Moreover, distinctions between workplace and residential buildings, including the presence of air conditioning units and differing occupancy patterns, lead to substantial differences in both IRC (p < 0.001) and TCF. The assessment of radon exposure based on room occupancy duration revealed substantial variations: workplaces showed lower actual exposure (62 Bq/m3 vs. 75 Bq/m3, p < 0.001), while residential settings, particularly at night, displayed higher exposure (278 Bq/m3 vs. 245 Bq/m3, p = 0.02) than integrated measurements suggest. Continuous monitoring systems offer critical insights into true radon exposure levels.

A Review of Radon Exposure in Non-uranium Mines-Estimation of Potential Radon Exposure in Canadian Mines

ABSTRACT

A worldwide review of radon exposure in non-uranium mines was conducted. Based on the reported radon measurements in a total of 474 underground non-uranium mines, the average radon concentration in underground non-uranium mines was calculated to be 570 Bq m -3 (varied from below detection limit to above 10,000 Bq m -3 ), and the average equilibrium factor between radon and its short-lived progeny was 0.34 (varied from 0.02 to 0.9). Using the average values from the review, annual effective radon doses to workers in Canadian non-uranium mines were estimated. For underground workers, the estimated annual effective radon dose to non-uranium miners was 3.8 mSv with the possibility of varying from 0.22 to 10 mSv depending on ventilation and other operation conditions. In Canada, the majority of mines are open-pit surface mines; only a small portion of the workforce in non-uranium mines physically work underground where radon concentration can be elevated. Averaged over the entire mining workforce, occupational exposure to radon in non-uranium mines is estimated to be 0.9 mSv. The results of this study indicate that there is potential for workers in non-uranium mines to reach or exceed Canadian thresholds for mandatory monitoring and reporting radiation doses, at least for underground operations.

Characterizing occupational radon exposure greater than 100 Bq/m3 in a highly exposed country

Radon is an established lung carcinogen concentrating in indoor environments with importance for many workers worldwide. However, a systematic assessment of radon levels faced by all workers, not just those with direct uranium or radon exposure, has not previously been completed. The objective of this study was to estimate the prevalence of workers exposed to radon, and the level of exposure (> 100-200 Bq/m3, 200-400 Bq/m3, 400-800 Bq/m3, and > 800 Bq/m3) in a highly exposed country (Canada). Exposures among underground workers were assessed using the CAREX Canada approach. Radon concentrations in indoor workplaces, obtained from two Canadian surveys, were modelled using lognormal distributions. Distributions were then applied to the susceptible indoor worker population to yield the number of exposed workers, by occupation, industry, province, and sex. In total, an estimated 603,000 out of Canada's 18,268,120 workers are exposed to radon in Canada. An estimated52% of exposed workers are women, even though they comprise only 48% of the labour force. The majority (68%) are exposed at a level of > 100-200 Bq/m3. Workers are primarily exposed in educational services, professional, scientific and technical services, and health care and social assistance, but workers in mining, quarrying, and oil and gas extraction have the largest number of exposed workers at high levels (> 800 Bq/m3). Overall, a significant number of workers are exposed to radon, many of whom are not adequately protected by existing guidelines. Radon surveys across multiple industries and occupations are needed to better characterize occupational exposure. These results can be used to identify exposed workers, and to support lung cancer prevention programs within these groups.

Regional cost effectiveness analyses for increasing radon protection strategies in housing in Canada

The incremental cost effectiveness ratios for implementing a recent recommendation to install a more radon resistant foundation barrier were modelled for new and existing housing in 2016, for each province and territory in Canada. Cost-utility analyses were conducted, in which the health benefit of an intervention was quantified in quality-adjusted life years, to help guide policymakers considering increasing investment in radon reduction in housing to reduce the associated lung cancer burden shouldered by the health care system. Lung cancer morbidity was modelled using a lifetable analysis that incorporated lung cancer incidence and survival time for localized, regional, and distant stages of diagnoses for both non-small cell and small cell lung cancer. The model accounted for surgical or advanced lung cancer treatment costs avoided, and average health care costs incurred for radon-attributable lung cancer cases prevented by the intervention. The incremental implementation of radon interventions in the housing stock was modelled over a lifetime horizon, and a discount rate of 1.5% was adopted. This radon intervention in new housing was cost effective in all but one region, ranging from $18,075/QALY (15,704; 20,178) for the Yukon to $58,454/QALY (52,045; 65,795) for British Columbia. A sequential analysis was conducted to compare intervention in existing housing for mitigation thresholds of 200 and 100 Bq/m³. This intervention in existing housing was cost effective at a mitigation threshold of 200 Bq/m³ in regions with higher radon levels, ranging from $33,247/QALY (27,699; 39,377) for the Yukon to $61,960/QALY (46,932; 113,737) for Newfoundland, and more cost effective at a threshold of 200 than 100 Bq/m³. More lung cancer deaths can be prevented by intervention in new housing than in existing housing; it was estimated that the proposed intervention in new housing would prevent a mean of 446 (416; 477) lung cancer cases annually. The cost effectiveness of increased radon resistance in foundation barriers in housing varied widely, and would support adopting this intervention in new housing across Canada and in existing housing in higher radon regions. This study provides further evidence that the most cost effective way of responding to the geographically variable radon burden is by implementing specific regional radon reduction policies.

Radon Survey in Bank Buildings of Campania Region According to the Italian Transposition of Euratom 59/2013

222Rn gas represents the major contributor to human health risk from environmental radiological exposure. In confined spaces radon can accumulate to relatively high levels so that mitigation actions are necessary. The Italian legislation on radiation protection has set a reference value for the activity concentration of radon at 300 Bq/m3. In this study, measurements of the annual radon concentration of 62 bank buildings spread throughout the Campania region (Southern Italy) were carried out. Using devices based on CR-39 solid-state nuclear track detectors, the 222Rn level was assessed in 136 confined spaces (127 at underground floors and 9 at ground floors) frequented by workers and/or the public. The survey parameters considered in the analysis of the results were: floor types, wall cladding materials, number of openings, door/window opening duration for air exchange. Radon levels were found to be between 17 and 680 Bq/m3, with an average value of 130 Bq/m3 and a standard deviation of 120 Bq/m3. About 7% of the results gave a radon activity concentration above 300 Bq/m3. The analysis showed that the floor level and air exchange have the most significant influence. This study highlighted the importance of the assessment of indoor radon levels for work environments in particular, to protect the workers and public from radon-induced health effects.

Evaluation of occupational radon exposure and comparison with residential radon exposure in Canada-a population-level assessment

Radon is a naturally occurring radioactive gas and presents everywhere on the Earth at varying concentration in workplaces and at homes. With Canadian labour statistics, time statistics and more than 7600 long-term radon measurements in workplaces, occupational radon exposure is evaluated for all 20 job categories based on North American Industry Classification System. Results are compared with residential radon exposure based on more than 22 000 long-term radon tests conducted in Canadian homes. The average annual effective dose due to radon exposure in workplaces is 0.21 mSv, which is lower than the average annual effective dose of 1.8 mSv from radon exposure at home by a factor of eight. Due to relatively higher radon concentration in residential homes and longer time spent indoors at home, exposure at home contributes to 90% of workers' total radon exposure (on average 1692 h in workplaces and 5852 h at homes). The analysis presented here is based on province-wide average radon exposures in various indoor and outdoor environments. Since the risk of developing lung cancer increases proportionally with increasing radon exposure, this evaluation indicates that on average reduction of radon levels in homes is very important and an effective way to reduce radon-induced lung cancers in Canada.

Study of baseline radon levels in the context of a shale gas development

This study reports the results from continuous measurement of indoor and outdoor radon concentrations in the area surrounding an unconventional shale gas exploration site in North Yorkshire, England, prior to the commencement of hydraulic fracturing. Public Health England has monitored the baseline radon levels in homes and in outdoor air in the Vale of Pickering since 2015. The statistical analysis presented here includes three full years (November 2015- -December 2018) of indoor and four and half years (October 2015 - April 2019) of outdoor radon measurements. Stratified sampling was used to select 171 dwellings in four areas, with two different radon potential. Statistical analysis confirms that homes in Kirby Misperton and Little Barugh and those in Yedingham are situated in areas with low radon potential, as was predicted by the UK radon potential map. On the other hand, both Pickering and Malton are confirmed as radon Affected Areas. Radon was measured continuously in the outdoor air using a newly developed outdoor kit containing passive radon detectors. The monitoring points were set up at 36 locations in the same local areas as those selected for the indoor monitoring. The results from statistical analysis show that outdoor radon had a different seasonality pattern to indoor radon. The monitoring of outdoor radon levels over the four and half years indicates a year-to-year variation in outdoor radon concentrations with levels fluctuating between 3 and 9 Bq m^-3. There was a very good agreement between long-term average radon concentrations measured using passive detectors and using an active AlphaGUARD monitor.

Estimating the burden of lung cancer in Canada attributed to occupational radon exposure using a novel exposure assessment method

Objective

Exposure to radon causes lung cancer. The scope and impact of exposure among Canadian workers have not been assessed. Our study estimated occupational radon exposure in Canada and its associated lung cancer burden.

Methods

Exposed workers were identified among the working population during the risk exposure period (1961–2001) using data from the Canadian Census and Labour Force Survey. Exposure levels were assigned based on 12,865 workplace radon measurements for indoor workers and assumed to be 1800 mg/m³ for underground workers. Lung cancer risks were calculated using the Biological Effects of Ionizing Radiation (BEIR) VI exposure-age-concentration model. Population attributable fractions were calculated with Levin’s equation and applied to 2011 Canadian lung cancer statistics.

Results

Approximately 15.5 million Canadian workers were exposed to radon during the risk exposure period. 79% of exposed workers were exposed to radon levels < 50 Bq/m³ and 4.8% were exposed to levels > 150 Bq/m³. We estimated that 0.8% of lung cancers in Canada were attributable to occupational radon exposure, corresponding to approximately 188 incident lung cancers in 2011.

Conclusions

The lung cancer burden associated with occupational radon exposure in Canada is small, with the greatest burden occurring among those exposed to low levels of radon.