Radon in ns. Helen Mersereau, MHSc Cape Breton University. Funded by Nova Scotia WCB and WorkSafeBC

Transcription

1 Radon in ns Helen Mersereau, MHSc Cape Breton University Funded by Nova Scotia WCB and WorkSafeBC

2 Uranium (U) Silver/gray metallic element 70% more dense than lead Found in most rocks, earth s crust and seawater Weakly radioactive Decays slowly, producing radon

3 Radon (Rn) Radioactive gas Found in soil, rock, water Invisible, odourless, tasteless Occurs naturally due to decay of uranium Decays further itself, emitting ionizing radiation

4 Radon (Rn) Moves freely through soil One of the heaviest gases under normal pressure Escapes to atmosphere or into buildings In outside atmosphere is diluted to insignificant amounts In confined or poorly ventilated areas of buildings it can accumulate to high levels, especially in the low lying areas.

5 How does radon accumulate? Building is built over bedrock or soil that contains uranium Air pressure in home is lower than surrounding soil Seeps in through: Cracks in foundation/walls Windows Floor drains and sumps Anywhere there is an opening where the building contacts the soil Aspirates from water (treatment, showers, etc.) water treatment plants are a concern

6 Why is radon a concern? Affects Indoor Air Quality (IAQ) worldwide Causes an estimated 21,000 lung cancer deaths per year in US 2 nd most frequent cause of lung cancer after cigarette smoking 8 to 15% of lung cancer is caused by radon 6 th leading cause of cancer overall A smoker who is exposed to radon has a much higher risk of lung cancer (5-20x greater) synergistic effect 14% of people who die from radon-related lung cancer have never smoked

7 Why is Radon a concern in NS? Nova Scotia has been identified to have higher than the national average of lung cancer Nova Scotia has been identified to have higher than the average radon level (geology based granite) NS also has high rates of smoking, which can act synergistically with radon to increase rates of lung cancer

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9 How does radon cause cancer? Because it is radioactive, radon decays Produces decay products, sometimes called radon daughters or radon progeny Two of these progeny decay rapidly themselves, and emit alpha particles. When alpha particles hit an object, the energy in them is absorbed by the surface of the object. Human skin is thick enough to not be affected If you breathe in alpha particles, they can damage bronchial and lung tissue, and can lead to lung cancer.

10 Radon and Lung Cancer Risk Exposure Level Bq/m 3 Non smoker Additional Risk 200 2% 17% 400 3% 22% Smoker Additional Risk 800 5% 30%

11 How is radon testing done? Radioactivity or the strength of a radioactive source is measured in units of Becquerel (Bq). 1 Bq = 1 event of radiation emission per second. Radon is measured in terms of Becquerel per cubic meter (Bq/m 3 ) May take long term measurements: (3 mos. 1 yr.) or short term measurements (less than 3 mos.) Long term more effective at attaining true values Alpha Track Detection

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13 Monitors

14 Measurement Locations in Public Buildings Taken From the Health Canada Protocols Preferred device locations should be: By an interior wall at breathing level, but at least 50 cm from ceiling. Where occupants spend much of their time. In occupied rooms in basements or the floor with the lowest level occupied rooms in the building. In rooms above crawl spaces, over slabs or built into the side of a hill with walls that may be in contact with the earth.

15 Measurement Locations in Public Buildings (continued) Devices should not be placed: In bathrooms, closets, cupboards, sumps, crawl spaces or nooks because relatively little time is spent there Near air currents caused by heating, ventilation, doors, windows or fans. Near heat, such as over radiators or in direct sunlight Near electrically powered equipment or appliances

16 Radon guidelines 2006 Health Canada dropped acceptable concentration of radon from 800 to 200 Bq/m 3 If >200 Bq/m 3, remedial action should be taken response time decreases with increasing levels found 200 to 400, 2 years to fix 400 to 600, 1 year to fix 600 to 800, 6 months to fix Radon levels should be reduced to a value as low as practicable New dwellings should use techniques that minimize radon entry and make future removal of radon easier.

17 Radon mitigation Soil Suction Sealing cracks and openings Pressurization Eliminate Radon in water Heat Recovery Ventilator

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19 Cape Breton University Study funding received from WorksafeBC and WCB of Nova Scotia part of reason for funding was NS has high levels of naturally occurring radon 200 radon monitors put in workplaces in Nova Scotia

20 What about workplaces? WorkSafe BC and Nova Scotia WCB approached for funding of workplace radon in NS Received funding for 200 radon alpha detectors Contacted workplace partners Put on education sessions for JOHSC Put monitors in place for 3 month periods at selected NS workplaces Results communicated directly to participants with advice for remediation

21 Radon Sampling Locations Nova Scotia

22 Radon Sampling Locations Cape Breton

23 NS Workplace Results Location Range of Results (Bq/m 3 ) Average Result (Bq/m 3 ) Sydney Lingan Wreck Cove Neil s Harbour Cheticamp Inverness Port Hawkesbury Pt. Aconi Trenton Lakeside Dartmouth St. Margaret s Bay Glace Bay Louisbourg North Sydney Coxheath

24 Workplace Findings Some workplaces were concerned about participating, unsure of how to deal with results Only one workplace had levels above 200 Bq/m 3, and then with only 2 of their 10 monitors, average was acceptable One other workplace had levels above the 150 Bq/m 3 action level. All other workplaces were acceptable

25 Additional CB Residential Survey Monitors provided to residents 3 month survey period Results reported to individual residents in a confidential manner (researcher blinded to location other than postal code) Advice given regarding Health Canada Standard and mitigation information Crack fill, positive pressure, etc.

26 Findings Results indicate 3 out of 20 need some form of radon mitigation, above 200 Bq/m 3 Indicates need for follow sampling in Howie Centre and Bras D or 5 out of 20 are above action limit of 150 Bq/m 3

27 CB Residential Results (20) Location/Cape Breton Range of Results (Bq/m 3 ) Average Result (Bq/m 3 ) Sydney Glace Bay Howie Centre Port Morien Bras D or Big Pond North Sydney

28 Concerns What happens if the results are high? Is funding available to help with mitigation costs? Who can help with mitigation design? Will the resident have to disclose radon information if selling house? Will radon affect home resale value?

29 Conclusion Radon is a carcinogenic, naturally occurring gas that is ubiquitous in the environment Seeps into buildings through cracks and other openings when air pressure is low inside Exposure to levels of radon over 200 Bq/m 3 for an extended period should be avoided, especially if you re a smoker New and existing homes and buildings should be tested for radon and if unacceptable levels are found, mitigation should be commenced

30 Thanks To WCB NS To WorksafeBC To safety services NS for invitation to speak To you for listening!

31 Questions?