RESUMEN
The radiation dose from internal radiation exposure is difficult to measure directly and hence different lung models were developed. The dose on the lung is the result of the regional deposition of aerosols carrying radon daughters in the respiratory tract. Deposition of aerosols can be take place during inhalation and exhalation in the 5 regions of the respiratory tract due to variation of aerosol sizes and other biological factors such as breathing rate. In this paper, a modified breathing rate is instead applied on the assumptions developed by the ICRP66 model to analyze the regional deposition of radioactive aerosols and a comparison has been made with the result of ICRP66 model deposition. According to the result, as the diameter of aerosols increases from 1 to 10 µm, the percentage deposition fraction in extrathoracic regions, in ET1 region increases from 6.53% to 48.43% and in ET2 region increases from 7.3% to 50.33%. The aerodynamic deposition of the attached fraction of radon aerosols along the bronchial regions (bronchi (BB), and bronchiolar (bb) region) is found small and almost constant. For 1 µm diameter aerosols, the percentage deposition is found 0.82%, for 5 µm diameter aerosols, the deposition is predicted 2.56% and at 10 µm the deposition is predicted about 1.93% in bronchi (BB) region. In the bronchiolar region (bb) for 1 µm aerosols, the deposition predicted is 1.5% and at 10 µm about 0.88% is predicted. The deposition of small size attached fraction of radon aerosols is found maximum in the alveolar region as compared to other regions of the respiratory tract and the deposition becomes almost negligible for large size aerosols in this region.
RESUMEN
Due to their electrostatic nature, radon decay products can attach to solid particles and aerosols in the air. Inhalation and ingestion are therefore the two main routes through which people are exposed to radon and its decay products. During the inhalation of these radioactive aerosols, deposition takes place in different regions of the human respiratory tract. The deposited aerosols carrying radon and its progeny undergo a continuous radioactive transformation and expose the lung to ionizing alpha radiation, which can destroy the sensitive cells in the lung, causing a mutation that turns cancerous. Radon which is a colorless, odorless, and tasteless radioactive noble gas is a major health concern and is the second leading cause of lung cancer. To address this, an indoor radon survey was conducted in many countries internationally, with results showing that indoor radon concentration has a seasonal variation. This is due to the fluctuation of environmental parameters and the geological nature of buildings. Its concentration was found to be maximum in the cool (winter) season and a minimum concentration was recorded in the warm (summer) season of the year.