Indoor Air Quality
James M. Rippe in Lifestyle Medicine, 2019
Radon-222 is a noble gas that is produced from the decay of uranium-238 and radium-226, which are naturally present in the earth’s rock and soil. It decays with a half-life of 3.8 days. It can diffuse itself into the soil and air before decaying. The breakdown of radon-222 occurs by emission of an alpha particle which produces radioactive progeny that include polonium-218 and polonium-214.34,35 These are known as the “short-lived” progeny, and they, in turn, break down into “long-lived” progeny that include lead-210, which yields bismuth-210, which yields the stable isotopes polonium-210 and lead-206. This whole decay process takes hundreds of years. When inhaled into the lung, the alpha-particles can damage cellular DNA and lead to mutagenesis in never-smoking lung cancer cases.36
Environmental Inhaled Agents and Their Relation to Lung Cancer
Jacob Loke in Pathophysiology and Treatment of Inhalation Injuries, 2020
Uranium in the earth's crust gives rise to decay chain products through radium 226 to the gas radon 222, which in turn gives rise to other isotopes collectively termed radon daughters (Parkes, 1982a). Radon 222 and the three radon daughters, polonium 218, polonium 214, and polonium 210, are important a-particles emitters. Thorium likewise decays into decay chain products of which thorium B (lead 212) and thorium C (bismuth 212) are a-particles emitters. All these products are emitted by soil, rocks, and building materials and are dispersed in the atmosphere to attach to water vapor, dust, or cigarette smoke particles, attaining aerosol sizes of 0.25-0.4 /rm (Davies, 1967). In this state, they can, on inhalation, penetrate well to the trachea, bronchi, and beyond (Parkes, 1982b) and exert their ionizing effect.
Home and Away
Alan Perkins in Life and Death Rays, 2021
The highest levels of radon have been found in Scandinavia, the US, Iran and the Czech Republic. Being a gas, radon seeps out of the earth and into the atmosphere. Radon-222 with a half-life of 3.8 days is the most stable radionuclide of radon and is responsible for the majority of public exposure to background radiation. It becomes a particular hazard to health when it enters buildings and closed spaces with poor air flow. The increasing use of building insulation and double glazing has resulted in the build-up of dangerously high concentrations of radon in some domestic properties, schools and workplace buildings. The main health hazard from radon is from lung intake through normal breathing. The biological damage occurs from the radon decay products, mainly polonium-218 and polonium-214 which become deposited in the bronchial tissues of the airways delivering the majority of the radiation dose to the lungs in the form of alpha particles. Epidemiological studies have shown conclusively that this is carcinogenic to humans and can cause lung cancer. In fact, radon is considered to be the second largest cause of lung cancer after cigarette smoking. Low levels of radon can also be found in drinking water but the release of the gas from water is negligible compared to other sources. Scientific studies have shown that the risk of stomach cancer and other gastrointestinal malignancies from radon in drinking water is small.
Radioactivity in building materials and assessment of risk of human exposure in the East Khasi Hills District, Meghalaya, India
Published in Egyptian Journal of Basic and Applied Sciences, 2020
The external hazard index (Hex) is an evaluation of the hazard of the natural gamma radiation emitted by the concerned radionuclides. This index value must be less than 1 (unity) to keep the contribution to the radiation hazard insignificant (European Commission, 1999). When the value of this index is less than 1 (unity), then the radiation received by occupants will be less than 1.5 mGy y−1. The inhalation of radon (222Rn) gas and its progeny products or ingestion of other radionuclides give rise to internal exposure. This exposure was measured by the parameter Hin. The expression for calculating Hex and Hin is given below [21,29]:
Correlation between cytogenetic biomarkers obtained from DC and CBMN assays caused by low dose radon exposure in smokers
Published in International Journal of Radiation Biology, 2019
Radon and its decay products emit high LET alpha radiation. Half of the human annual background radiation exposure occurs because of the Radon-222 (Robertson et al. 2013). High doses of ionizing radiation causes detrimental effects in humans such as chromosomal damage (Ulsh et al. 2015), mutations (Vilenchik and Knudson 2006), carcinogenesis (Evrard et al. 2005; Krewski et al. 2006) etc. Data related to low dose ionizing radiation effects is limited and there is an increasing concern towards the risk of low dose exposure because of frequent flyer risks, screening tests for cancer, occupational exposure, manned space exploration etc. (ICRP 1999; Gilbert 2001). At present, risks of low dose exposure are derived by linear extrapolation from higher doses which might not truly reflect the low dose risk (Mitchel 2007; Matsumoto et al. 2009; Wheeler and John Bailer 2013; Desouky et al. 2015). Because of lack of understanding of the molecular consequences of low dose exposure, ambiguity exists on the risks of low dose in human beings (Kim et al. 2015).
An examination of radon awareness, risk communication, and radon risk reduction in a Hispanic community
Published in International Journal of Radiation Biology, 2020
Chrysan Cronin, Michael Trush, William Bellamy, James Russell, Paul Locke
Radon-222 is a naturally occurring radioactive decay product of uranium-228 which is present in the earth’s crust. It is a direct decay product of radium-226. Radon-222 has a half-life of 3.82 days. Because radon is a gas it can move out of the rock to both water and to ambient air where it can become trapped inside homes and other buildings, rising to levels that are unsafe (Darby et al. 2005; ICRP 2014). Although radon is an inert gas, a large proportion of radon progeny will deposit in the lungs and are not exhaled. Two of these progeny, polonium-218 and polonium-214 emit alpha particles, which disrupt cellular DNA and can lead to the development of lung cancer (Harley et al. 2008). In 1992, the US Environmental Protection Agency (EPA) classified radon as a carcinogen (EPA Citizen’s Guide 1992) due in large part to evidence set forth by the BEIR VI committee report. According to the report, epidemiological evidence from studies in the general population supported previous results presented in the BEIR IV report that showed that exposure to radon was associated with an increased risk of lung cancer. In addition, new information that showed the molecular and cellular basis of carcinogenesis by alpha particles was considered by the committee. The committee concluded that there were 15,400–21,800 excess lung cancer deaths occurring each year in the US in never smokers due to radon exposure (BEIR VI 1992). Annually, exposure to radon is the second leading cause of lung cancer after smoking and is associated with over 21,000 deaths in the US (Lantz, Mendez and Philbert 2013; NCI 2018). The average indoor and outdoor air levels of radon in the US are approximately 1.3 pCi/L (48.1 Bq/m3) and 0.4 pCi/L (14.8 Bq/m) respectively (EPA Citizen’s Guide 1992).
Related Knowledge Centers
- Alpha Decay
- Beta Decay
- Gamma Ray
- Lung Cancer
- Radioactive Decay
- Thorium
- Radon
- Half-Life
- Decay Chain
- Double Beta Decay