How does radiation affect us?
Radioactive materials released from a source can affect the human body via a number of pathways. Some may be transported by winds or water to our vicinity. These radioactive substances can affect us through direct irradiation and may be inhaled or ingested.
In general, we might be affected by radiation through the following two exposure pathways:
- Plume exposure pathway - inhalation of radionuclides, direct irradiation from airborne or deposited radionuclides.
- Ingestion pathway - intake of contaminated water or ingestion of contaminated food.
In the unlikely event of a nuclear accident, released radioactive materials behave in the same way as a cloud of smoke called radioactive plume, dispersing into the atmosphere following the winds. Inert gases such as xenon and krypton will travel downwind while diluting rapidly. Some of the volatile substances, such as iodine, caesium and tellurium, will have already condensed into particles by the time they reach the atmosphere. These particles will be deposited on areas affected by the plume with the amount of deposition decreasing with distance. Rainfall will greatly enhance the deposition rate. When radioactive materials deposit onto the ground or into the sea, they will be absorbed by crops, livestock and marine organisms and enter our food chain. We will then be affected by consuming these contaminated crops and livestock. For information on health effect of radiation, please click here. For information on radiation protection, please click here.
Hong Kong Observatory has installed an Accident Consequence Assessment System (ACAS). Based on information of the source term and meteorological conditions, the ACAS models the transport and dispersion of the radioactive plume and predicts the associated exposure. Department of Health has also developed a food chain model to simulate exposure pathways in the food chain to determine the effect of radioactive materials on each of our organs.