Presentation on theme: "Indoor Air Quality and Health, Radon Testing and Mitigation CIPHI 77 th Annual, June 28, 2011 Halifax, NS Greg Baytalan, B.Sc., C.P.H.I.(C) Air Quality."— Presentation transcript:
Indoor Air Quality and Health, Radon Testing and Mitigation CIPHI 77 th Annual, June 28, 2011 Halifax, NS Greg Baytalan, B.Sc., C.P.H.I.(C) Air Quality Specialist, Interior Health Kelowna, BC
Health Impacts of Air Quality The mortality burden is substantially larger than that attributed to other public health issues to which considerable public resources are directed; much larger than homicide, and two-thirds the burden of deaths associated with motor vehicle accidents. (1)
Air quality is also recognized as being responsible for increases in hospital admissions and emergency room visits (largely from respiratory and cardiovascular conditions), limitations in personal activity, work and school absenteeism. The annual cost of the burden of disease from air pollution in BC may be about $167 million. (1)
Global Air Quality Impact Global mortality related to outdoor air quality estimated to range from 200,000 – 799,000 deaths or 0.4 – 1.4% of all annual deaths (2) Exceeding WHO guideline for particulates, accounts for roughly 2 – 5% of all deaths in the rapidly expanding urban developing world (2) Indoor air pollution may be even more damaging in terms of overall disease burden, with outdoor and indoor air pollution together estimated to be responsible for nearly 5% of the global burden of disease (2)
Radon – Canadians typically Spend 90% of time indoors (3) (Note: Stack should exit above roof)
WHAT IS RADON? Radon is a colourless, odourless, radioactive gas that occurs naturally in the environment. It comes from radioactive decay of uranium, and can be found in soils and rocks. Outdoors radon mixes with fresh air - concentrations are negligible –Outdoor concentrations range from Bq/m3 with an average of 15 Bq/m3 Indoors radon can accumulate to high levels and become a health concern – Dwelling (house/building) concentrations range from 30 - >2000 Bq/m3 with an average of 45 Bq/m3
Rn Radon (222) 86 Radon is a naturally occurring radioactive gas.
Four Important Properties of Radon 1. Unstable emits radiation! 2. Chemically inert, invisible, odourless, tasteless Hard to detect! 3. Heavier than air can accumulate in home! 4. Gas at RT can be inhaled!
How does Uranium become Radon?
Challenges – We Can’t See, Smell, Taste or Feel Radon
Average worldwide exposure to natural radiation sources
Radon Units USA measurement is picocurie (pCi), 1 pCi/l = 2.22 disintegrations/min/liter International Systems (S.I.) measurement Becquerel (Bq), 1 Bq/m3 = 1 disintegration/second/m3 In air 1 pCi/l = 37 Bq/m3 USA EPA Action Level 4 pCi/l (148 Bq/m3) Health Canada Guideline 200 Bq/m3 (5.4 pCi/l)
History 1400’s, Bohemia (Czech Republic) silver miners with mysterious lung disease, determined as Radon induced lung cancer centuries later (4) 1898, German physicist Fredrick Ernst Dorn discovered Radium to give off a gas, Radon. Newfoundland miners research, 1950’s exposure >50,000 Bq/m3 1950’s Radon identified as a hazard in uranium mines 1975 Radon detected in Port Hope homes
History Continued 1984, Stanley Watras, Limerick Nuclear Plant worker, bringing Radon progeny from home into plant and setting off alarm (5) (home tested 2,700 pCi/l (99,900 Bq/m3) (6) USA EPA and Pennsylvania turned house into a laboratory for Radon and Radon Decay Products and mitigation evaluation (10) Mitigation achieved <4 pCi/l (10) (USA EPA Action Level is 4 pCi/l)
1976 Federal Provincial Task Force on Radioactivity sets criterion at 0.02WL 150 Bq/m Former guideline of 800 Bq/m 3 adopted 1999 BEIR-VI report is published on Radon risks 2004 Appearance of European and North American combined analyses of studies linking residential radon exposure with lung cancer 2004 Health Canada recommended lowering the radon guideline to 200 Bq/m Federal Provincial Territorial Radiation Protection Committee (FPT RPC) approves HC recommendation June, 2007 Minister of Health adopts Radon 200 Bq/m 3 guideline (last 7 bullets, Health Canada)
REASONS FOR CHANGING THE GUIDELINE 1.Clear evidence of a real risk of lung cancer at 800 Bq/m 3 (and as low as 200 Bq/m 3 ) 2.Risk is high enough to justify intervention 3.Harmonization with international radon guidelines and practices 4.Significant number of lives to be saved (~400/year) if all homes remediated to less than 200 Bq/m 3
HEALTH IMPACTS OF RADON The health effect associated with exposure to radon is an increased risk of developing lung cancer. 8-15% of lung cancers are attributable to radon. Exposure to radon causes approximately 1900 lung cancer deaths per year in Canada Radon exposure is the most important cause of lung cancer in non-smokers. Risk of lung cancer due to radon depends on the concentration and length of exposure.
-As radon decays, it emits alpha particles, which can damage DNA in lung cells -Radon decay products, plate out on lung cells, and continue to irradiate causing further damage. Radon and Decay Products Damage DNA
DNA Damage Increases Risk To Lung Cancer Radiation can damage a lung cell’s ability to a) Controlling cell growth b) Control cell replication c) Repair damaged DNA Lifetime exposure to elevated radon levels increase the risk to lung cancer.
LIFETIME RISK FOR SMOKERS Radon Level (Bq/m 3 ) Lifetime Risk Smoker Lifetime Risk Non-Smoker Background12%1% 20017%2% 40022%3% 80030%5% The combined effects of radon exposure and smoking create a RISK greater than the two actions separately
RADON EXPOSURE RISK COMPARISON We take precautions against accidental deaths by putting on seatbelts, wearing life jackets and changing the batteries on our smoke detectors – we should be testing our homes for radon *All accidental deaths includes motor vehicle accidents, drowning, falls, fires and more
Health At 200 Bq/m3 action level, 347 lives can be saved each year in Canada through prevention and mitigation EPA estimates 1 life saved annually from lung cancer for every 1,542 existing homes mitigated and 5,292 new homes built to Radon standards 2009, WHO looking at 100 Bq/m3 Effective total dose delivered is 97% from Radon decay products, and 3% from Radon USA, ~21,000 lung cancer death/year from Radon EPA estimates that living with 10 pCi/l (370 Bq/m3) is equivalent to smoking 1 pack of cigarettes per day
Health Alpha particle radiation is primary concern, easily absorbed by surrounding tissue, physical and chemical damage to DNA, cell stays alive with mutation potential → cancer Radon decay products (progeny or daughters) are the majority of health risk Generally: Inhalable particles 10 microns (µm) and greater considered filterable by upper respiratory tract. Respirable particles <10 µm can get deep into the lungs with 2 micron fractions and less considered highly respirable
Radon Progeny Radon Gas – radioactive, inert, no static charge, not detected by human senses Radon Decay Products - radioactive, chemically reactive, heavy metals, temporary static electric charge, not detected by human senses, primary source of cell damage in lungs, airborne and respirable (5) Short-lived Radon progeny in domestic environment is largest contributor of natural radiation exposure to public (9) Measuring Radon decay products is difficult and very seldom measured, we measure Radon Air circulation causes Radon decay products to plate out faster
Size Comparisons: (note: nanometer (nm): m, micrometer (micron) (µm): m) High Efficiency Particulate Air Filter (HEPA) (HEPA 99.97% efficiency when tested at aerosol of 0.3 µm diameter (8) Measured progeny at 1 – 150 nm (0.001 – 0.15 µm) diameter (7),unattached progeny <4 nm nm (0.004 µm) and attached progeny 100 – 400 nm (0.1 – 0.4 µm) (9) Most of unattached fraction deposited in lungs, and deposition of <2 nm (<0.002 µm) short-lived progeny increases cancer risk; 80% of attached fraction exhaled, unattached about 10% of activity, yet 50% of total radiation dose (9)
Radon Sources Sources to air in order - soil, ground water, oceans, phosphate residues, uranium tailings piles, coal residues, natural gas, coal combustion Radon concentration in soil ranges from 750 Bq/m3 to >3,700,000 Bq/m3, most soils between 7,400 and 74,000 Bq/m3 Radon in ground water ranges from 3,700 to nearly 120 million Bq/m3 Radon in outdoor air ranges from 1,100 Bq/m3 (1,500 during temperature inversion)
- When a house is heated, the hot air rises -Fewer air molecules in the lower level of house causes slight vacuum. -Creates suction on the soil drawing Radon into the house.
Mitigation Old method – chase cracks. Not effective, not a stand alone approach, not a long term approach, many holes in house, Radon will find a way in. Examples, a) block wall permeability can vary by a factor of 100, b) house highly sealed for success, a few weeks later back to normal high levels. New method – depressurize soil, put soil under less pressure than house so as to create reverse movement. Pressure field extension, sub-slab communication test, locate suction point away from major leakage sites Largest slab ever mitigated with 1 suction point was a ½ million square foot slab at a Johnson City, Tennessee hospital (5)
Radon Mitigation Strategies 1. Source removal – get rid of the radon 2. Ventilation solutions 3. Entry point sealing 4. Active soil depressurization system
Sampling Short term versus long term Health Canada recommends no less than 3 months ideally between October and April Subject to: Barometric pressure changes, heavy rainfall, sunrise/sunset, wind, freezing Ventilation is not a good predictor, so don’t use as an indicator of low or high Radon as it is not strongly correlated to Radon concentration Testers can have +- 20% precision variation (send duplicates, blanks, spikes) Always promote retesting
Radon Testing in Homes -Place device in lowest lived-in level of home -Away from windows and doors -Typical breathing zone height -Test for at least 3 months RADON Device Placement
Radon in Water 10 minute shower can raise bathroom to 30 pCi/l (1,110 Bq/m3) Contribution from soil gas far greater than from water Potential concern for well water systems Average adult exposed to <2 liters/day water, approximately 20,000 liters/day air Stomach intestines less vulnerable than lungs, cells regularly shed, food absorbs radiation USA estimate range 75 – 400 deaths per year due to Radon in public water supplies (lung, digestive); 13,700 stomach cancers in 1998 of which Radon projected to cause 18 EPA proposing new standard
Radon in Water - continued Testing air during periods of no water usage may miss Radon entry via water Can check water for Radon Gas; if doing a broad scan mineral analysis check also for Radium
1. Remedial measures should be undertaken in a dwelling whenever the average annual radon concentration exceeds 200 Bq/m 3 in the normal occupancy area. Health Canada Recommendations 1
2. The higher the radon concentration, the sooner remedial measures should be undertaken. Health Canada Recommendations 2
3. When remedial action is taken, the radon level should be reduced to a value as low as practicably possible. Health Canada Recommendations 3
4. The construction of new dwellings should employ techniques that will minimize radon entry and will facilitate post-construction radon removal, should this subsequently prove necessary. Health Canada Recommendations 4
2010 National Building Code Available for purchase Nov. 29, 2010 From: National Research Council of Canada, Ottawa Protection from Soil Gas Ingress Applies to residential and other buildings Clean granular material (100 mm (4 inches) gravel) Poly barrier Rough-in subslab depressurization; Pipe (100 mm (4 inch) dia.) extended into gravel Clearly marked for Radon only, and capped
2010 BC Building Code Under Review National Code provides guidance; Provincial Code dominates All kinds of change requests thereby renders reluctance to implement changes Competing with localized views versus scientific knowledge - They want evidence Tectonic Plate Study & BCCDC Report; essentially Hope eastward is of primary Radon concern (although found in lower mainland and Island) Hopeful for adoption of National Code language Hope eastward
Mitigation by Depressurization
Information (Education) Public Net > Health & Safety > Air Quality > Indoor Air Quality > Radon safety.aspx?id= safety.aspx?id=10438 Health Canada Pamphlets & CMHC Booklets (free) Health Canada Website:http://www.hc- sc.gc.ca/ewh-semt/radiation/radon/index- eng.php “RADON – ANOTHER REASON TO QUIT” pamphlet posted by the end of June 2011http://www.hc- sc.gc.ca/ewh-semt/radiation/radon/index- eng.php Good Site: Health Physics Society Ask a Radiation expert. Thank you
References (1) Interior Health Air Quality Performance Improvement Plan 2007 – 2010, page 4 - 5, vementPlan pdf vementPlan pdf (2) British Columbia. Provincial Health Officer. (2004). Every Breath You Take…Provincial Health Officer’s Annual Report Air Quality in British Columbia, a Public Health Perspective. Victoria, BC Ministry of Health Services, Chapter 5, page 51 – 53, (3) The Lung Association (4) RadonSeal, “The Stealthy Radon Gas” (5) & generally those not referenced) Midwest Universities Radon Consortium, U.S. EPA founded Radon Training Centre, Radon Measurement and Mitigation Courses, May/June 2010 (6) Wikibin, “Stanley Watras” (7) K.W. Tu & E.O. Knutson, “Indoor Radon Progeny Particle Size Distribution Measurements Made with Two Different Methods”, Radiation Protection Dosimetry, (1988) 24 (1-4): (8) Andrew F. Oberta, “The Truth About HEPA Filters”, The Environmental Consultancy, (9) A. Mohamed, A. A. Ahmed, A. E. Ali, M. Yuness, “Attached and Unattached Activity Size Distribution of Short-Lived Radon Progeny (214Pb) and Evaluation of Deposition Fraction”, Journal of Nuclear and Radiation Physics, Vol.3, No. 2, 2008, pp (10) Active Rain, “Have Your Heard the Story of Stanley Watras?”, Purple border slides Health Canada, tan & red border slides & slides 28, 29 & 37 CMHC