# Hazardous Materials and Wa ste Management Division Air Screening Concentrations Table

The Division has prepared a table listing indoor air remediation goals and action levels for a number of volatile organic compounds to be used at sites where vapor intrusion may be a concern. This was prompted in response to the U.S. Environmental Pr otection Agency having rele ased a new assessment of the health effects of Trichloroe thene (TCE), which was one of the most commonly used degreasing solvents. Existing air concentrations were also updated to incorporate the 2009 EPA risk assessment guidance for the inhalation pathway presented in Ri sk Assessment Guidance for Superfund (RAGS) Part F 1 

## . Another notable change is th e Division’s decision to adopt EPA’s June 2003 OSWER directive for Tetrachloroethene (PCE) (OSWER No. 9285.7-75)

These new air screening concentration table values replace those that may be present in other older guidance documents, such as Table 1 found in th e March 2006 “Dry Cleaner Remediation Guidance Document.” With the release of this new table, the Division hereby withdraws the use of both the August 20, 2004 and August 17, 2006 interim risk evaluation and management policies for TCE and PCE, respectively.

Development and quality checking of the numbers liste d in the Air Screening Concentrations Table will be an ongoing process and readers are encouraged to report any errors that may be discovered to the Division. Please be sure to cons ult the footnotes to the table when using these table values.

If you have questions about the deri vation or application of these tabl e values, please contact the Division by email sent to comments.hmwmd@state.co.us . Please be sure to put "Avramenko" in the subject line.

1 

## U.S. EPA (2009). Risk Assessment Guidance for S uperfund Volume I: Human Health Evaluation Manual (Part F, Supplemental Guidance for Inhala tion Risk Assessment). OSWER 9285.7-82; January 2009. Office of Superfund Remediation and Te chnology Innovation. EPA, Washington D.C.

# Air Screening Concentrations

Volatile organic compounds are chemicals that have a high va por pressure (molecular weight < 200 g/mol and Henry’s Law Constant > 10 -5 

### atm m 3 

### / mol) and easily form vapors at normal temperature and pressure. This definition applies to a large number of organic compounds, many of which are manufactured chemicals. From this long list of chemicals, the Department has chosen those typically found in the environment at chemical release sites.

The analytical method presently being used to determine the concentrations of VOCs in indoor air is the Compendium Method TO-15 , selected ion monitoring (SIM) m ode, as specified in EPA document EPA/625/R-96/010b using the specific Colorado Guidance for Analysis of Indoor Air Samples (April 2000) ( http://www.cdphe.state.co.us/hm/airsmpl.pdf ). The laboratory must demonstrate to the Department its ability to perform this analys is with quantitatively reliable results down to levels that equ ate to health-based con centrations for the chemicals of concern.

Target indoor air concentrations for those chemicals not included on this list may be found in the EPA Regional Screening Level table. Always check for the most recent version of th e EPA Regional Screening Level table, the link to which is: http://www.epa.gov/reg3hwmd/risk/human/rb-concentration_ta ble/Generic_Tables/pdf/master_sl_table_bwrun_NOV2011.pdf

Chemical Abstracts No. Chemical Name (IUPAC) Risk Basis

C=Cancer NC=Noncancer Residential Remediation Goal 1 (R=10 -6 , HQ=1)

μ g/m 3 Residential Action Level (R=10 -5 , HQ=1) ug/m 3 Worker 6 Remediation Goal (R=10 -6 , HQ=1) ug/m 3 Worker 6 Action Level (R=10 -5 , HQ=1) ug/m 3

71-43-2 Benzene C 1 0.31 3.1 1.6 16.0 56-23-5 Carbon tetrachloride C 1 0.41 4.1 2.0 20.0 108-90-7 Chlorobenzene NC 2 52 52 220 220 67-66-3 Chloroform C 1 0.11 1.1 0.53 5.3 95-50-1 1,2-dichlorobenzene NC 3 210 210 880 880 106-46-7 1,4-dichlorobenzene C 4 0.22 2.2 1.1 11 107-34-3 1,1-dichloroethane C 4 1.5 15 7.7 77 107-06-2 1,2-dichloroethane C 1 0.094 0.94 0.47 4.7 75-35-4 1,1-dichloroethene NC 5 7.3 7.3 30.1 30.1 156-59-2 Cis-1,2-dichloroethene -- No value* No value* No value* No value* 78-87-5 1,2-dichloropropane C 4 0.24 2.4 1.2 12 100-41-4 Ethylbenzene C 4 0.97 9.7 4.9 49 75-09-2 Methylene chloride C 1 5.2 52 26 260 100-42-5 Styrene NC 1 1,000 1,000 4,400 4,400 79-34-5 1,1,2,2-Tetrachloroethane C 4 0.042 0.42 0.21 2.1 127-18-4 Tetrachloroethene C 4 0.41 4.1 2.1 21 108-88-3 Toluene NC 1 5200 5200 22,000 22,000 71-55-6 1,1,1-Trichloroethane NC 1 5200 5200 22,000 22, 000 79-00-5 1,1,2-Trichloroethane -- 0.15 ( C 1 ) 0.21 (NC 2 ) 0.77 ( C 1 ) 0.88 (NC 2 ) 79001-6 Trichloroethene -- 0.43 ( C 1 ) 2.1 (NC 1 ) 3.0 (C 1 ) 8.8 (NC 1 ) 75-01-4 Vinyl chloride C 1 0.16 1.6 2.8 28 1330-20-7 Xylenes (Mixture/Total) NC 1 100 100 440 440

Note: Indoor air target concentrations based on non-carcinogenic risk correspond to a hazard quotient (HQ) of 1. For facilitie s where multiple non-carcinogenic chemicals are present, HQ values should be divided by a factor of 10 to account for additivity. If a djusted table values are exceeded, consultation with a toxicologist is r ecommended to assess likely imp act on specific target organs. *- Currently, no toxicity value is availabl e for the inhalation pathway. Please cont act the Department for additional informat ion on a sitespecific basis. IUPAC – International Union of Pure and Applied Chemistry

1 Source of toxicity value: EPAIRIS; 2 Source of toxicity value: EPA PPRTV; 3 Source of toxicity value: EPA HEAST

4 Source of toxicity value: Cal EPA; 5 Source of toxicity value: CDPHE

6 Worker values are considered protective for indoor office work ers with occasional contact with outdoor soil, and for outdoor wo rkers engaged in light to moderate activity. Values are NOT APPLICABLE to outdoor workers routinely engaged in contact-intensive act ivity. For facilities where contact intensive use is anticipated, additiona l analysis and consultation with a toxicologist will be req uired to determine appropriate site-specific inpu ts to the risk equations.

The screening values are derived from a variety of sources. Pa rties using this table should pe riodically check these sources t o verify that the posted values are still in use.

December 15, 2011 Version

# Application of Screening Levels for Carcinogens Example of Tetrachloroethene (PCE)

Risk Range Action Required Residential Use Air ( μ g/m 3 

### ) Worker Use Air ( μ g/m 3 

### )

Less than or equal to 1x10 -6 

### or background No Further Action, measures to reduce PCE concentrations in air not required ≤ 0.41 ≤ 2.1

Between 1x10 -6 

### and 1x10 -5 

### Provided soil and/or ground water contamination is being remediated as approved by the Department, continued monitoring of indoor air is likely unnecessary. 0.41 to 4.10 2.1 to 21

Greater than 1x10 -5 

### Further study needed to determine whether or not the source is from subsurface releases. Mitigation is required it is determined that the vapors are derived from a subsurface source. > 4.1 > 21



# Application of Screening Levels for Mixed Cancer and Noncancer Effects Example of Trichloroethene (TCE)

Risk Range Action Required Residential Use Air ( μ g/m 3 

### ) Worker Use Air ( μ g/m 3 

### )

Less than or equal to 1x10 -6 

### or background No Further Action, measures to reduce TCE concentrations in air not required ≤ 0.43 ≤ 3.0

Between 1x10 -6 

### (cancer)

and HI=1 (noncancer) Provided soil and/or ground water contamination is being remediated as approved by the Department, continued monitoring of indoor air is likely unnecessary. 0.43 to 2.1 3.0 to 8.8

Greater than HI=1 Further study needed to determine whether or not the source is from subsurface releases. Mitigation is required it is determined that the vapors are derived from a subsurface source. > 2.1 > 8.8

# Application of Screening Levels for Non-Carcinogens Example of 1,1-Dichloroethene (1,1-DCE)

Risk Range Action Required Residential Use Air ( μ g/m 3 

### ) Worker Use Air ( μ g/m 3 

### )

Less than or equal to HQI=1 or background No Further Action, measures to reduce 1,1-DCE concentrations in air not required ≤ 7.3 ≤ 30.1

Greater than HQI=1 Further study needed to determine whether or not the source is from subsurface releases. Mitigation is required it is determined that the vapors are derived from a subsurface source > 7.3 > 30.1



## For sites with multiple contaminants or exposure pa thways, cleanup levels should result in a cumulative hazard quotient equal to or less than one for all those constituents with similar critical endpoints.

For sites with multiple contaminants , cleanup levels should be set so th at the risk posed by individual constituents does not exceed a 1x10 -6 

## and where the cumulative (total) excess upper bound lifetime risk from all contaminants does not exceed a 1x10 -5



## . In all cases, further analysis may be warranted if an action level is exceeded that would trigger the need to mitigate exposures, particularly if it is believed that the constituents are derived from sources other than what may be present in soil or ground water. In th ese cases, lines of evidence should be examined to determine whether the observed concentrations are from a subsurface source or background (activities/products within the structure being sampled). If the lin es of evidence indicate a subsurface source, the Division will require remedial actions to mitigate exposure. A discussion on conducting a line of evidence analysis may be found in Section 4.1 of the CDPHE’s September 2004 Draft Indoor Air Guidance ( http://www.cdphe.state.co.us/hm/indoorair.pdf ) and Section 3.7.3 of ITRC’s January 2007 Vapor Intrusion Pathway: A Practical Guideline ( http://www.itrcweb.org/Documents/VI-1.pdf ).