In my previous blog, I wrote about indoor air pollution. We know that indoor air is not better than outdoor air and sometimes even worse. The pollutants present are- Radon, Molds, Volatile organic compound( VOCs), Carbon monoxide, Dust particles. In this post, we will talk about the pollutant Radon which is natural radioactive noble gas. Radon is a colorless, odorless, dense gas, and the primary source of indoor pollution.
Radon in outdoor quickly dilutes in the atmosphere where it is not a problem. Due to the small space radon concentration indoor is quite high. The outdoor radon concentration ranges from 5-15 Bq/m3 and 10-10,000 Bq/m3 for indoor.
Science of radon decaying-
Radon is produced by the natural decay of uranium found in rock and soil. Decay starts with uranium-238 forms thorium-234, protactinium- 234m, uranium -234, thorium-230, radium-226, and radon -222. Radon on further decaying by emission of alpha and beta particles to- polonium-218, bismuth, and lead known as radon progenies or daughters.
Radon in air and water-
Radon is carcinogenic in nature so its monitoring is necessary in risk areas. Radon has numerous sources- uranium we already discussed, other sources are construction materials like- cement, sand, granite, tiles, cooking gas, and groundwater. Radon and progenies escape from the pores on the surface called emanation and mix with gases like- carbon dioxide and methane which further diffuse in the atmosphere by crossing the soil-air boundary. Radon also mixes with underground water making water unhealthy for drinking.
Health effects of radon-
Radon is one of the most important chemical responsible for lung cancer in non-smokers. With an increase in the number of lung cancer among non-smokers, the attention shifted towards air pollution. According, to a study among nationwide cases of lung cancer 52.1% are non-smoker, 41.8% in male, and 88% in females. According to the director of AIIMS, this increase in the number of lung cancer is related to indoor air pollution and the same stat can be seen in outdoor air pollution.
Radon and progenies when breath get trapped in the lungs and with time they start decaying by emitting alpha and beta radiation changing the DNA and causing lung cancer. Radon when mixes with water can cause stomach cancer.
Radon statistics for some Indian states-
Indoor Radon level in dwellings using cup dosimeter ( Ramachandran et al 1995)
Reducing radon content-
A proper ventilation system is the best way to remove radon from indoors. Exhaust fans and electric purifiers can dissipate gas from indoor to outdoor. This is the best and easy way to reduce radon concentration. Since there is no such threshold value for this gas inside the house even a small quantity of this gas can be harmful. The safe limit suggests keeping this level at zero but 0-48 Bq/ m3 is considered normal. According to WHO the radon level should not exceed 300 Bq/ m3.
Radon gas moves inside the home through cracks and gaps, so it is advisable to seal floorings and walls to keep the concentration below the safe level.
According to study-"Atlas for radon" which is conducted for different types of construction materials is analyzed for contributing in radon content-
1) Plaster and whitewash (wall) with mosaic cement/mosaic wood/ mosaic tile flooring- Significant contribution.
2) Mosaic floor with plaster whitewash/ wood flooring-Significant contribution.
3) Wood wall with mosaic/cement flooring- small contribution.
4) Plaster and paint (wall) with cement and mosaic flooring- No contribution.
So it is advisable to choose the appropriate construction materials for your house.
Very nice piece of information about outlining a radioactive pollutant
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