Evaluation On Indoor Air Quality Of A Radon Spring Hotel

IntroductionRadon(222Rn)is a natural radioactive gas which has been classified as a carcinogen to human by the International Agency for Research on Cancer(1).Previous studies have indicated that population were widely exposed to indoor low-dose radon,which may cause radioactive damage to human body.On the other hand,radon spring therapy has been applied more and wider to relieve symptoms of some specific diseases.Thus,radon springs were exploited in the world,and many hotels and spas for leisure and entertainment were built surrounding the springs.As a special public place,Radon spring hotels have a relatively high exposure level of air radon.However,it remains to elucidate that whether indoor radon exposure is within the safe radioactive level and whether the release of radon through water spas is a harmful risk to the workers of thermal installations as well as for customers.In this study,we selected a radon spring hotel surrounding to Chengtian Radon Spring,Taishun,Zhejiang,and carried out researches on indoor air quality monitoring and evaluated the potential effects on human health,in order to provide scientific basis for the utilization of Chengtian Radon Spring.MethodsSampling sites were set up in the radon spring hotel in July,September and December 2017.222Rn,PMlo,PM2.5 and CO2 concentrations were measured by a RAD7,carbon dioxide detector and DUSTMATE monitor and then the pollutants levels were compared with the limit standards.In addition,indoor air radon and water radon levels were monitored by different approaches to mimic different bath ways,and environmental factors such as ambient temperature,humidity,water pH and other environmental factors were recorded in the meanwhile.The personal and occupational exposure dosages for 'model' customers and workers were estimated according to the monitoring radon concentrations.Results1)Air radon concentrations monitoring and population effective exposure dose estimationIndoor air radon levels were sorted in descending order:hotel rooms(26.39±21.01 Bq/m3),restaurants(15.27±7.40 Bq/m3),spring pumping rooms(12.70±8.00 Bq/m3)and were lower than the reference level of World Health Organization(100 Bq/m3).Outdoor air radon concentrations(5.29-5.45 Bq/m3)were lower than the population-weighted worldwide level of outdoor radon(10 Bq/m3).Dynamic radon concentration in the bathroom(7.95-135.00 Bq/m3)and bedroom(8.20-65.70 Bq/m3)monitored by different bath ways were almost lower than the reference level of world Health Organization.For customers,the annual effective doses of indoor radon estimated by different bath ways were 6.59×10-3 mSv and 4.53×10-3mSv.The annual effective dose of hotel staffs and pumping workers were 0,155 mSv and 0.073 mSv.The estimated annual effective doses were lower than the effective dose limit of population and workers of China.2)Water radon levels monitoring and water-air transfer coefficients estimationThe average radon concentration in water in the closed bathroom and the open radon spa were 6247.5±2647.6 Bq/m3 and 4478.5±1633.8 Bq/m3.The average radon concentration in water in the spring was 31000.0±2533.0 Bq/m3.There was a large loss of radon in water during the transmission and storage from the spring storage.And the high transfer coefficients(8.84×10-4-7.16×10-3)showed hot spring water might contribute to air radon concentration in the bathrooms.3)Other air quality evaluationAir CO2 concentrations in the hotel were much lower than the limit of Hyginic standard of Hotel(700 ppm).The PM2.5 levels were lower than the 24-hours average concentration limit of primary standard of China(35 ?g/m3),and the PM10 levels were almost lower than the concentration limit of Hyginic standard of Hotel(150 ?g/m3).ConclusionsThe indoor radon levels in the hotel were lower than the reference level of WHO,and spring water bath will not be harmful to customers.However,it is quite necessary for population involved in radon exposure works to reduce radon concentrations to prevent the potential health hazards.It is recommended that customers should open the ventilation devices when taking a bath,control the bathing time and what's more,avoid drinking spring water.Hotel staffs and pumping workers should keep doors and windows open during work to reduce radon exposure.