Vapor Intrusion (VI):

Transcription

1 Vapor Intrusion (VI): EPA s Experiences with Analogous Gases USEPA Workshop: Addressing Regulatory Challenges AEHS West Coast Conference San Diego, CA Mar. 15, 2011 Presented by: Henry Schuver, DrPH USEPA Office of Resource Conservation & Recovery (ORCR) See: &

2 EPA s experiences with the intrusion of chemical contaminant vapors 10 yrs ago RCRA developed & issued national guide for chemical VI 2001 RCRA Guidance for VI to support defensible RCRA EI Human Exposures determinations 10 yrs of workshops held by RCRA w/ ORD (tech. transfer & research) support Objective was to improve the science & benefits of VI efforts Science = based on hypotheses that have been adequately tested Not untested opinions Benefits = documented reductions in exposures (and risks) Today s Goal = Integration of what we have learned for chemical VI with what the Agency has learned from research and experience assessing and managing the intrusion of analogous soil gases

3 EPA & the Intrusion of Soil Gases 1984 Watras home Radon gas levels (~ 2700 pci/l) discovery of widespread naturally occurring VI Agent was (naturally occurring) radon Began massive national research effort (methane VI even earlier, but more localized) 1986 National Labs (LBL) predict similar VI for VOC chemicals 1990s chemical spills VI: EPA s Air & Superfund, MA, CT, CO, But not well linked to earlier radon work 2001 RCRA & 2002 OSWER Guidance for chemical VI Also not well linked to earlier radon work 2008 Agent is moisture (and mold) documented benefits of VI controls and 20? Agent will be CO, CO2, pesticides, termiticides, herbicides OSWER Guidance for chemical VI is being written Scientist know Soil gas is not good for indoor air quality & it is getting worse, w/ energy efforts (weatherization) e.g., EPA 430 F January 2009, & EPA s draft Healthy Indoor Environ. Protocols for Home Energy Upgrades w/ section for chemical VI ( Below Ground Contamination ) Non scientists are generally ignorant: That all evidence shows preventing soil vapor intrusion into indoor air is beneficial (Despite LEED, Health Homes 2010, USEPA & State Radon Programs and Health Dept., WHO ) Public health would be significantly improved if all buildings prevented/controlled VI

4 Most studied, Highest Risk: Radon Research involved National Labs & SAB in decades of science & policy development (global now) Health risk (residential indoor air): ~ 20,000 excess lung cancer cases per year in the US Majority of disease due to low radon levels (i.e., < 4 pci/l) due to # people No evidence of a threshold carcinogen (Linear response) Extrapolated from Miners Est. Lifetime excess (lung) cancer risk for the gen. public (including smokers) ~ 2/100 4 pci/l Decades of Residential studies with exposure misclassification (RR = E/U) Studies w/ min. of 1 yr long sample for homes/persons to participate 2005 N. Am. and Europ. residential disease rate (epi) meta analyses each show risks ~ 2/100 for the general public (incl. smokers) 2010 Global (w/ Asia) meta analysis analysis shows similar risks, & WHO recommends a step up on responses to radon

5 Radon workers are ahead of us

6 How analogous is radon intrusion? Radon intrusion is generally analogous to near slab chemical Vapor Intrusion (VI) (Mosley 2004; 2007; McHugh 2008) However, there are some differences at depth: (Schuver & Mosley 2009) 1) Spatial heterogeneity of the chemical contaminant source zones (e.g., large areas with 0 conc.) [vs. generally distributed & near surface] 2) Temporally varying spatial dimensionsi of a mobile (e.g., vapor or groundwater plume migration) source area [vs. geol. stable source] 3) Temporally varying source concentration at a given point within a source area over time (e.g., 10x pulses in GW) [vs. solid parent source] 4) Transient t( (non equilibrium) i following a release (prior to vapor diffusion front /equilibrium reaching the surface (USEPA CSM))[vs. 5 by] 5) Variable degradation rates +/ than for constant Rn 6) Chemicals influenced by geology deeper than 3 Rn ½ lives These suggest chemical VI prediction is even less predictable

7 Note variability similar to Dr. Steck s 1 day data Typical VOC sample duration Rightslink Copyright Clearance License No

8 Summary of Radon Conc. (Bq/m 3 ) Hubbard et al (Sweden) Sample Factor (Max. Min.) Range Period 1 Day 80x <10 to yr Week x 70 to yr Year 1.3x 180 to yr ~ four year period Nov July 1994

9 1 Day samples (chemicals) Folkes et al., indoor air samples of 1,1 DCE (24 hr samples) 45 unmitigated (low conc.) homes Data from 2 to 10 years (w/ Qtr annual frequencies) The [indoor air] normalized [by property annual average conc.] values ranged [max. min.] from about 10% (0.1x) to about ten times (10x) the annual average of the home Range of variation = 2 orders magnitude (100x) 68% of samples w/n +/ 2 to 3x of the homes annual mean ~100% of samples w/n +/ 10x of the homes annual mean Winter concentrations tended to be highest and summer was about 50% lower than the annual mean Short term variability can overwhelm any seasonal trend [very similar to comment by Rowe (2002) for radon]

10 Overview of EPA s Radon Guidance & Programs Large # of guidance documents (for Home Owners & Sellers) 4 Regional Centers for Training and Certification for Rd Radon monitoring i & mitigation 5 days of training with 1000s of slides summarizing conclusions from years of research & experience Personal Recommendation: All chemical VI workers should participate in radon training, be able to pass the (national/state) tests, & be certified (NEHA/NRSB/State) for both monitoring & mitigation to gain decades of VI experience

11 Some Basic Features of EPA s Guidance for Radon VI Implementable (w/ consistency & comparability) Defensible assessment & management Scientifically & Legally Cost effective Benefits > costs Readily achievable control level of 4 pci/l Congressional long term goal Indoor not > Outdoor Benefits to Building Occupants/Owners (nationally) Health Economy

12 EPA s Recommendations for Radon Assessment (1994) Test your home Test = Sample [Indoor Air] Only indoor air integrates all 4 classes of variables (source, path, building, weather) Test b/c it is Not [quantitatively] predictable from exterior samples and/or models Test your home b/c it is building specific (See: Drs. Dawson & Wertz presentations) This can be put in a Standard Operating Procedure that is: Standardized Repeatable Comparable Defensible Note, does not use external Multiple Lines of Evidence (due to variability in MLE) Dr. Daniel Steck will illustrate details of the science behind EPA s recommendation for radon Assessment

13 EPA s Recommendations for Radon Mitigation Decisions (1994) Resample if: One short (2 90 day) sample shows > 4 pci/l SAB did not allow use of samples with <2 diurnal cycles (min. 48 hrs) from occupied (or possibly occupied) portions of building Mitigate t if: Closed house cond. if <7 day sample; + 12 hrs prior if only 2 3 day Location criteria away from floor, walls, and openings Criteria for unusual weather conditions Criteria for unusual building conditions/operations Average of two short (2 to 90 day) samples, or One long term (>90 day) sample, is >4 pci/l in indoor air Dr. Leo Moorman will illustrate details of the science & experiences behind EPA s recommendations for Mitigation

14 #1 Recommendation for VI Worldwide Since the early 1990s: Both The U.S. Surgeon General and EPA recommend that all homes be tested [for Radon]. EPA supports the World Health Organization s (WHO) recent projectto to increase awareness, collect data, encourage action to reduce radon risks globally Meanwhile US clean up authorities have been assessing homes for possible chemical VI, typically without much consideration of Radon, recommendations by WHO, SG, EPA

15 The RCRA program is now considering: A general e recommendation e o that when Responsible Parties (RP) are accessing homes for possible chemical contaminant vapor intrusion: their assessment could be more direct, comprehensive, informative and support global recommendations for health: If they help & involve building occupants with the If they help & involve building occupants with the collection of samples for Radon

16 USEPA Indoor Environments Division s opinion of the RCRA suggestion: i.e., voluntary collection of samples for Radon such a recommendation is entirely and appropriately consistent with two of our policy and key public messages (1) you don't know (your radon level) unless you test; (2) every home should be tested (EPA and Surgeon General's recommendation). Phil Jalbert, Executive Secretary» Federal Interagency Committee on Indoor Air Quality (CIAQ)

17 Some Possible Benefits of Sampling for Radon Low cost semi quantitative tracer of all VI Simple passive sorbent (e.g., charcoal canisters) Continuous digital monitors (like Smoke & CO detectors) Could provide signature of the building s response to environ. changes Help identify most appropriatetimestimes for short term chemical IA testing Provides a service and value to building occupants Raises knowledge/awareness of naturally occurring Radon risks Help home owners appreciate variability between buildings & across time Gives context for chemical VI risks Allows comparisons between radon and chemical VIrisks* risks*, e.g., Radon/Chemical VI risk ratio* Highlights one of the multiple benefits of preventing soil gas intrusion into indoor air (radon) *typically only lung cancer risks

18 More Possible Benefits of Sampling for Radon 1) Engages the community in the process as they could control the placement of monitors 2) Encourages direct indoor air measurements (of at least a relevant tracer of soil gas intrusion) 3) Highlights one of the multiple benefits of preventing soil gas intrusion into indoor air (radon) 4) A clear reminder that there are real benefits to 4) A clear reminder that there are real benefits to controlling soil gases intruding into indoor air (besides COCs)

19 Considerations from EPA s Experiences with Radon VI & Community Input Leverage relevant pre existing analyses & policies Radon science & policy Make Standard Operating Procedures (SOP) Implementable (consistent & comparable) Defensible for both assessment & management Scientifically & Legally Cost effective Costs& Benefits of Assessment vs. Control Provide Benefits impacted building occupants Health (when possible consider VI more holistically than COCs) = avoided premature disease/death Control (when possible allow citizens to choose testers/mitigators*) Economy As possible, employ local labor & expertise for needed testing & mitigation system installation, operation, maintenance & monitoring issues *Radon testing/mitigation training and certifications help FY 2011 Environmental Workforce Development and Job Training oswer oblr pdf

20 Thank You Best wishes providing service & benefits to Best wishes providing service & benefits to chemical VI impacted communities.