Inhalation dose in the indoor environment of Eloor industrial area, Kerala, India

Radon (222Rn) and Thoron (220Rn), the members of Uranium and Thorium decay series respectively, are ubiquitous in nature. Being airborne alpha active radioisotopes, they are the major contributors of inhalation dose especially in the indoor environments. This study measures the Potential Alpha Energy Concentration (PAEC) of radon/thoron progenies in the dwellings of Eloor industrial region in Kerala and thereby evaluate the internal/inhalation dose to the population. Aerosol samples were collected from 100 locations in the study area using high volume air sampler and gross particulate activity measurement was done using ZnS(Ag) alpha counter. The PAEC of radon progeny in the study area varied from 0.13 to 2.94 and that of thoron progeny varied from 0.3 to 7.7. It has been observed that the dwelling with marble floor possesses relatively higher concentration of radon and thoron progenies while lower concentrations were observed in dwellings with tile floors. Taking the mean concentrations of 222Rn and 220Rn progeny levels of 100 samples collected, the inhalation dose was 0.14 mSvy-1 for radon and 0.09 mSv y-1 for thoron, which delivers a total inhalation dose of 0.23 mSv y-1 to the population residing in that area. Measured data show below compared to the ICRP recommended action level of 3–10 mSvy-1 for general populace. Although measured data requires no immediate action to reduce the hazardous radon and thoron level in the studied area, however the radiation risk from such hazardous gas is not completely discarded. Since human spent more than 80% of time in indoor and the radiation hazards follows linear no threshold model, therefore the indoor environment should be well ventilated to reduce any unexpected health hazards. •222Rn and 220Rn are the major contributors of inhalation dose in the indoor environments.•PAEC data on radon/thoron progeny in Eloor industrial area scarce.•ZnS(Ag) alpha counter was used to measure PAEC of Rn/Tn progeny.•Measured data show below compared to the ICRP action level of 3–10 mSvy-1 for general populace.