Radon in Chelsea September 2014 Louis-Marie Poissant, M. Sc. Env.
Outline 1. Understanding radon 2. Health risks related to radon 3. Cancer and probability 4. Importance of taking long term measurements 5. Radon in well water (new)
1. Radon Radon is a colorless radioactive gas that is odorless and tasteless. It results from the natural breakdown of uranium in soil, bedrock and water.
Occurrence and concentration The radon present in the ground is released into the atmosphere. It is very diluted: very low concentration, 10-12 grams per cubic meter. It is not really a concern (radioactivity: about 7 becquerels per cubic meter, Bq/m 3 ).
Density of gas and houses This gas is formed in the rock (granite like Chelsea). Under certain conditions it rises to the surface. Houses function as a vacuum, especially in cold weather and when the ground is frozen.
What happens to the radon? Radon enters through the basement and has a tendency to remain there When radon enters an enclosed space, such as a house, the ensuing accumulation can sometimes lead to high concentrations. Radon breakdown emits alpha radioactive particules.
Physical Characteristics Alpha particles emitted Noble gases (chemically inert) Alpha particles emitted uranium
How radon gas enters a house A house always tends to pull in outside air like a chimney
2. Health risks related to radon The only known risk of radon exposure is an acute risk of contracting lung cancer. When present in the air we breathe, radon can reach the lungs. There it continues to decompose and emit "alpha particles" (see Figure 1) absorbed by the surrounding lung tissue. This energy damages and destroys lung cells.
Tissue damage by alpha particles Alpha particles Damage to chromosomes Tumor (lung cancer) MSSS
3. Cancer and probability When lung cells are damaged, they can cause cancer when they reproduce (multiply). Cancers caused by radioactivity are coincidental, and not everyone who is exposed to radon will develop lung cancer. Many years go by between the time of exposure and the onset of the disease. The risk of developing lung cancer due to radon depends on the concentration of radon in the air you breathe and the duration of exposure.
Cancer and probability When it comes to cancer risk, there is no safe level (no risk) For example: ultra-violet rays and X-rays one ultra-violet ray or a single X-ray can theoretically give cancer.
Odds are similar to 649 lottery Chance to win big at 649: 1/13 983 816 with one ticket 1/13 983 with 1000 one time ticket "Chance" of dying from lung cancer by radon (lifetime exposure): 5 people out of 100 (5%) at 800 Bq/m 3 exposure 2 people out of 100 (2%) at 200 Bq/m 3 exposure How much risk is acceptable?
Acceptable? Health Canada considers that the old guideline of 800 Bq/m3 was too risky: it was equivalent to the probability of death for ALL accidental deaths combined: 5 out of 100 people (car, bike, drownings, fires, etc.). 200 Bq/m3 is more appropriate ( 2 out of 100 people) Around 2 out of 100 people Around 5 out of 100 people Life exposure to radon(nonsmoker All accidental deaths combine Bush pilote Mont Everest ascension Poisoning
Smoking and radon Smoking increases the risk of lung cancer. Exposure to the two (radon and smoking) significantly increases this risk. At 200 Bq/L life exposure: 2 % chance for non-smokers 17% chance for smokers Outside air exposure: about 1% lung cancer risk
4. Long term measurement Radon hourly mean within a house Beginning of January to the end of March 1995 Min 37 Bq/m 3 Max 370 Bq/m 3 Real mean: 140 Bq/m 3
Long term measurement, or in winter Radon hourly mean within a house Begining of January 1988 to January 1993 Min 37 Bq/m 3 Max 370 Bq/m 3 Real mean: 130 Bq/m 3
5. Radon in well water More likely in Chelsea: Well, uranium Radon is a gas and like any gas, it`s soluble in water. The more the water is cold, the more radon is soluble (champagne, soft drinks, trout) Shower: Hot water droplets: radon released quickly into air
Ingestion Water in the stomach and intestine, thus radon and plutonium Negligible compared to radon released from water into the air. Approximately 10%.
Inhalation Added to radon in air from other sources: rock, ambient air Can vary a lot in a day (hot water use or not)
How radon gas enters a house
What to do in Chelsea? Recommendation Measure in air: If more than Bq/m3 in the air, and if you have an artesian well: measure in water. You will get an idea of the proportion that comes from water Health Canada guideline: 2000 Bq/L: limits migration of radon from water to air
Reducing the concentration of radon ALARA: As Low As Reasonably achievable Increase mechanical ventilation with a heat recovery ventilator (HRV) (you will win by doing this regardless). Seal cracks and openings in foundation walls and floors, and around pipes and drains; painting the floor. Ventilate the false floor of the basement with a small pump to expulse the radon. Active depressurization of the soil. Consult an accredited business specialized in the mitigation of radon infiltration.
And radon in water? If you have a lot of radon in water to the point that it contributes to the concentration in air: Use degasification techniques
Additional information Radon tests: www.pq.poumon.ca, www.chelsea.ca On the Ministère de la santé et des services sociaux web site (msss.gouv.qc.ca) Accredited companies: for info on mitigation methods and radon measurement
Questions?