Radon gas: the road to awareness

The National Nuclear Regulator (NNR) aims to bring awareness to South Africans regarding the potential threat of a naturally occurring radioactive gas, called radon, to draw up a map of potential high and low risk areas in the country and to set action and mitigation levels to minimise risk. This was envisaged and initiated by the Centre for Nuclear Safety and Security (CNSS).

An emaciated man caught my eye as I was watching a Carte Blanche programme.

It was Grant Hatch, sharing with the television viewers his conviction that radon gas was the cause of his wife’s death. Neither Grant nor Heather had been smokers. Yet they had developed lung cancer, and apparently paid the price for fifteen years of life on their fruit farm near Barrydale. There was no proof, he added, that this toxic gas was responsible for the tragedy that would take his own life and leave his young sons without their parents.

With the impulse to explore this potential threat in our natural environment, I began research which led me to Dr Rikus le Roux, an investigator and colleague of Professor Jacques Bezuidenhout of the Faculty of Military Science of Stellenbosch University. They are working on a radon gas survey of South African homes, schools, hospitals and working environments.

Dr. Le Roux agreed to test the house where I was staying.

“I’ll place the measuring instruments at desk level. Radon is a heavy gas which dissipates the higher it rises. Please don’t move them for three days, until I collect the electrets and calculate the radon concentration in the house.”

What is radon? And how does it get into our homes?

Radon is an inert gas naturally present in our environment.

Second most common cause of lung cancer after smoking

The World Health Organisation (WHO) estimates radon to be the second most common cause of lung cancer after smoking. Radon raises the risk of lung cancer, with an estimated one million deaths every ten years worldwide. Being colourless, odourless and tasteless it is impossible to identify directly.

Uranium, commonly found in granitic rocks, is the beginning of a chain of decay. As uranium releases radioactive particles into the atmosphere and surrounding matter, it undergoes transformation into numerous elements. One of these is radon, the only gaseous element in the chain. This gas accumulates in low-lying areas, potentially seeping into buildings through cracks in floors and walls, through drains, construction joints, loose fitting pipes and also through exposed soil. The gas is water soluble and, in extreme cases, may make its way into a building’s water supply.

The presence of this gas is therefore a potential risk in the air which we breathe. When radon is inhaled, the radioactive particles from the gas may be trapped in the lungs, where it decays over a period of 3.8 days, forming elements such as polonium, bismuth and lead. The inner tissue of the lungs also absorbs the alpha and beta radiation emitted by this process.

”The ionising process damages the tissues, “ Professor Bezuidenhout explains.

“It is an energy deposit in the lungs.”

And the risk of stomach cancer? According to the Environmental Protection Agency (EPA) of the USA. it poses less than that of lung cancer.

Ventilation is the key to protection

Where is it likely to be found, I asked. High radon risk is associated with mining tailings, the presence of coal, and in certain building materials as well as phosphate fertilisers. A study of radon in coal mining areas has been undertaken by Dr. Le Roux, as well as numerous studies around mine tailings.

“We consider South Africans generally to be in the lower risk category, because of our temperate climate,” explains Dr. Le Roux.

“Greater risk is involved in cold climates where buildings lack natural ventilation, and everything is locked up to keep out the cold. Basements are the worst.”

He mentioned the results of testing a room occupied by a student who kept the windows and doors closed. A level in excess of 300 becquerel per cubic meter (Bq/m3) was measured. (According to the WHO, a level below 100 Bq/m3 is considered safe. Between 100 and 200 Bq/m3 mitigation is recommended, whereas a level exceeding 300 Bq/m3 is considered a health hazard.) By providing natural ventilation through open windows, the level in the student’s room was reduced to 50 Bq/m3.

The exposure rate is an important factor, and lifestyle plays a part. A healthy approach in a well-ventilated home is the first step to ensuring safety from this potential health hazard.

Though the majority of lung cancer deaths occur among smokers, the recent passing of Grant and Heather Hatch have highlighted the situation of lung cancer death due to natural causes. Grant’s conviction that his health had been compromised by the presence of radon in his home was given credence by the fact that levels of over 500 Bq/m3 have been registered in the area.

With his wife spending most of her time with their four young sons at college in Somerset West, Grant would close the farmhouse, while he traveled for his agricultural consulting business in Africa. It was due to his research experience as a lecturer in Agricultural Science at Pietermaritzburg University that he came across the potential hazards of radon gas.

“I wish people would become more aware of this” the sentiment of a family member who has the radon detecting device which Grant found online.

In September 2019 the Ninth International Conference on protection against radon at home and work was held in Prague in the Czech Republic, where a regulatory framework is now in place. Several countries have completed data on radon risk areas, including Australia. The Australian Radon Action Plan is being considered at national level, raising awareness and investigating mitigating actions. The mitigating level being 200 to 300 Bq/m3.

Mitigating the risk

Testing radon levels will, at the least, offer peace of mind. According to the WHO, basic procedures can reduce indoor levels by more than 50%, viz.

• Increasing under floor ventilation,
• avoiding passage of radon from the basement to living areas,
• sealing floors and walls,
• the use of a radon sump,
• ensuring adequate ventilation of a building,
• using extractor fans,
• in the case of basement risk, chimneys from underground to roof level.
• inserting radon resistant sheets into foundations and flooring in new homes. (According to an article on Health24 published in 2016)

As part of the project in South Africa, certain areas have been targeted for sampling to date:

• the West Coast peninsula and Paarl due to the granitic outcrops of the area,
• the Gauteng mines and
• parts of Mpumalanga for its coal fields.

The goal is to first obtain a baseline for statistical risk before rolling out the study to the rest of the country. Random tests should cover equal shares of the community – “from shanty towns to glass palaces,” quipped Professor Bezuidenhout.

And what about this house where I was staying? No shanty town, no glass palace, but the results were surprising.

“The levels are higher than we might have expected. We would advise you to ensure the house is well ventilated, then we could return to retest at a later stage if you wish,” suggested Dr. Le Roux.

“It would be useful to test other properties in the immediate vicinity to get a clearer picture.”

A becquerel refers to the amount of ionising radiation released when an element such as uranium spontaneously emits energy as a result of the radioactive disintegration of an unstable atom. One becquerel represents a rate of radioactive decay equal to one disintegration per second.

The following studies were undertaken by Professor Bezuidenhout and Dr. Rikus Le Roux:

• The Anthropogenic Impact on Indoor Radon Concentrations for Secunda
• The influence of different types of granite on indoor radon concentrations in West Coast dwellings
• Indoor radon measurements for the West Coast Peninsula
• The Effect of the coal industry on indoor radon concentrations in eMalahleni

By Heather Green