Contribution of 222Rn-bearing water to indoor radon and indoor air quality assessment in hot spring hotels of Guangdong, China

This study investigates the contribution of radon (222Rn)-bearing water to indoor 222Rn in thermal baths. The 222Rn concentrations in air were monitored in the bathroom and the bedroom. Particulate matter (PM, both PM10 and PM2.5) and carbon dioxide (CO2) were also monitored with portable analyzers. The bathrooms were supplied with hot spring water containing 66–260 kBq m−3 of 222Rn. The results show that the spray of hot spring water from the bath spouts is the dominant mechanism by which 222Rn is released into the air of the bathroom, and then it diffuses into the bedroom. Average 222Rn level was 110–410% higher in the bedrooms and 510–1200% higher in the bathrooms compared to the corresponding average levels when there was no use of hot spring water. The indoor 222Rn levels were influenced by the 222Rn concentrations in the hot spring water and the bathing times. The average 222Rn transfer coefficients from water to air were 6.2 × 10−4–4.1 × 10−3. The 24-h average levels of CO2 and PM10 in the hotel rooms were 89% and 22% higher than the present Indoor Air Quality (IAQ) standard of China. The main particle pollutant in the hotel rooms was PM2.5. Radon and PM10 levels in some hotel rooms were at much higher concentrations than guideline levels, and thus the potential health risks to tourists and especially to the hotel workers should be of great concern, and measures should be taken to lower inhalation exposure to these air pollutants.

► 222Rn-bearing water is the main contributor to indoor radon in hot spring hotel.
► The PM2.5 and CO2 are also the main indoor pollutants in the hotel rooms.
► Higher radon and PM levels might have significant negative health effects to human.
► The radon transfer coefficients are consistent with the published data.