Radon testing is the only sure way of knowing the level of radon concentration you and your loved ones are exposed to. Unlike most developed countries, Kenya presently neither has national guidelines nor action levels for radon concentration in dwellings and other indoor places. It is important to note that radon is an isotope with isotopes of concern in relation to radiation protection being Rn-222 and Rn-220. Also important to note is that while Rn-220 is not considered much of a risk in developed countries by virtue of its short half-life, and bearing in mind the nature and type of building materials used in these countries, documented research shows that Rn-220 can significantly contribute to radiation exposure in earthen dwellings such as those found in parts of rural Asia and Africa. In rural Kenya for example, most dwellings and in some rare instances elementary schools are constructed using earthen building materials.
The World Health Organization (WHO) proposes that homeowners should take remediation measures in the event Rn-222 in their homes exceeds 100 Bq/m3. European guideline for Rn-222 action level in dwellings on the other hand is 400 Bq/m3 for existing houses and 200 Bq/m3 for future dwellings. The International Commission for Radiological Protection (ICRP) recommends intervention on the basis of risk index quantified in terms of annual effective dose, with 3-10 mSv/y adopted as a basis for Rn-222 remediation in dwellings and workplaces. Kenya needs radon guidelines customised to suit the Kenyan needs. Kenya needs action levels for not only for Rn-222 but also for Rn-220. Kenya needs to come up with action levels that are attainable, for existing dwellings and work-places as well as for future buildings. For this to be feasible, large scale discriminative-radon measurements techniques (simultaneous measurement of Rn-222 and Rn-220) are needed to complement the on-going small-scale studies being undertaken by researchers in various universities in the country such as Kenyatta University.
Below are some of the measures that can be employed to determine and reduce radon levels at home and work-places.
Testing For Radon Concentration
This involves use of radon-discriminating test kits for simultaneous determination of both Rn-222 and Rn-220 concentrations in indoor air. The test kits are typically deployed in the area of interest for a period of 60-90 days. At the end of the deployment period, the kits are analysed in a lab, the isotope concentrations evaluated and the risk index determined.
Radon determination in groundwater for domestic use
Many households in Kenya rely on groundwater from lakes, rivers, wells and boreholes for domestic use. Groundwater may contain high levels of Rn-222 depending on the soil profile it was in contact with. When used indoors, Rn-222 may escape from the water hence adding to the radiological risk attributable to radon. Such water should therefore be tested for radon levels to determine if it is suitable for use in confine spaces. Some countries in Europe have set up radon action level in water of 200 Bq/m³ with a target level of 100 Bq/m³. Presently, there are no national guidelines regarding radon levels in the country.
Mitigating against elevated radon levels in indoor air
Many households in Kenya rely on groundwater from lakes, rivers, wells and boreholes for domestic use. Groundwater may contain high levels of Rn-222 depending on the soil profile it was in contact with. When used indoors, Rn-222 may escape from the water hence adding to the radiological risk attributable to radon. Such water should therefore be tested for radon levels to determine if it is suitable for use in confine spaces. Some countries in Europe have set up radon action level in water of 200 Bq/m³ with a target level of 100 Bq/m³. Presently, there are no national guidelines regarding radon levels in the country.
Some of the ways of reducing elevated levels of radon in existing and future buildings include the following;
Increasing air circulation
Outdoor air contains very low levels of radon and when allowed to mix with indoor air, the indoor radon levels are diluted. Air circulation can be enhanced by;
• Keeping the windows open for as long as is possible
• Use of vents in situations where windows are not available or cannot remain open
• Using air conditioning units such as fans.
Plastering or limning the inner surfaces of earthen dwelling with appropriate material
Raw soil when used as a building material acts as an important source of not only Rn-222 but also Rn-220 largely because of the high porosity of the resulting building material. To reduce the probability of the isotopes escaping into indoor air from the walls and floor of an earthen dwelling, the walls can be lined up with, for instance cardboard, which may stop nearly all Rn-220 and most of Rd-222 from exhaling from the building material. After some time, the trapped isotopes decay to particulate progenies which lodge in the building material thus becoming of little radiological risk. The walls and the floor may also be plastered with a material of low radionuclide content and one that serves as a barrier between the earthen material and the indoor air.
Sealing cracks and crevices in the house
Rn-222 is the isotope of concern in most modern houses. The main source of the isotope is the underlying soil. Once generated in the soil, Rn-222 being longer lived compared to Rn-220 may seep into indoor air through cracks and crevices in the basements and parts of the wall inconstant with soil. Sealing these entry points can play a significant role in reducing indoor radon concentration.
Treating groundwater before use
To ensure ground water has as little radon as possible, it should be treated before being used inside buildings. The treatment process helps release radon from water.
Using approved anti-radon building materials
Future construction should be done using materials with low Rn-222 and Rn-220 exhalation rates. Firing earthen building materials for example may reduce their porosity hence lowering the exhalation rate of Rn-220.
Stay ahead in radon knowledge
Be informed on the radon situation of a house before moving in. If putting up own house, go for radon-resistance materials, in addition to adopting building designs and techniques that promote air circulation.
Radon is the leading cause of lung cancer among non-smokers. Radon-induced lung cancer takes time, even years, to manifest. Testing and addressing possible elevated radon concentration is one way of fighting against radon cancer among us and our loved ones. Let us join hands as KeRA fraternity and friends to promote radon safety and cancer-free living.
REFERENCES AND FURTHER READING
Butiki GW, Makokha JW, Masinde FW, et al. Annual effective dose from radon-222 concentration levels in underground water in bungoma south sub - county, Kenya. Int J Hydro. 2021;5(1):23-26. DOI: 10.15406/ijh.2021.05.00261
Rotich CK, Hashim NO, Chege MW, Nyambura C. Measurement of radon activity concentration in underground water of Bureti Sub-county of Kericho County Kenya. Radiat Prot Dosimetry. 2020 Dec 30;192(1):56-60. doi: 10.1093/rpd/ncaa193. PMID: 33294927.
Nyambura, Catherine; Tokonami, Shinji; Hashim, Nadir; Chege, Margaret; Suzuki, T; Kudo, H and Hosoda, Masahiro. (2019). Annual effective dose assessment due to radon and thoron progenies in dwellings of Kilimambogo, Kenya. Radiation protection dosimetry. 184. 430-434. 10.1093/rpd/ncz090.
Tokonami S, Sun Q, Akiba S, Zhuo W, Furukawa M, Ishikawa T, et al. Radon and thoron exposures for cave residents in Shanxi and Shaanxi provinces. Radiat. Res. (2004) 162:390–6. doi: 10.1667/RR3237
https://www.frontiersin.org/articles/10.3389/fpubh.2019.00113/full
https://www.who.int/news-room/fact-sheets/detail/radon-and-health
https://www.icrp.org/docs/Radiological%20Protection%20against%20Radon%20Exposure%20consultation.pdf