Effect of plastering and paints on radon exhalation rate and radon effective dose from fired bricks

In the present study, we estimate the effect of paints on the radon exhalation rate from building materials. For the experimental study some bricks were collected from the local market of Aligarh district, Uttar Pradesh, India. They were coated with a soup of cement and sand, and then dried for at least 24 h. After drying, the coated bricks were plastered with whitewash and re-dried for a minimum of 2 h. They were then ready to be painted with different colours of paints from different brands. Radon exhalation rate and effective dose were measured for the painted brick samples by adopting sealed can technique, which utilizes LR-115 type-II track detectors. The radon activity varied from 768.8 to 1529.8 Bq m^–3 and exhalation rate varied from 460.1 to 915.6 mBq m^–2 h^–1, whereas the dose equivalent for radon daughters varied from 54.2 to 107 mSv yr^–1. Exhalation of radon in the case of Snowcem (limeproof yellow), Asian Paints (peach organza) and Berger Paints (yellow breeze) was found to increase slightly, while it decreased for the other paint brands.