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0 <br /> AECOM Environment <br /> TABLE 1 -California Human Health Screening Levels for Indoor Air and Shallow Soil Gas <br /> Chemical Indoor Air Human Health Screening Shallow Soil Gas Human Health <br /> Levels(Ng/m') Screening Levels(Ng/m') <br /> Residential Commercial/ Residential Commercial/ <br /> Land Use Industrial Land Use Land Use Industrial Land <br /> Only Use Only <br /> TPHG NA NA NA NA <br /> Benzene 8.40 E-02 1.41 E-01 3.62 E+01 1.22 E+02 <br /> 3 3 3 3 <br /> Ethylbenzene Postponed Postponed Postponed Postponed <br /> Toluene 3.13 E+02 4.38 E+02 1.35 E+05 3.78 E+05 <br /> m-Xylene 7.30 E+024 1.02 E+034 3.19 E+054 8.87 E+054 <br /> o-Xylene 7.30 E+024 1.02 E+034 3.15 E+054 8.79 E+054 <br /> p-Xylene 7.30 E+024 1.02 E+034 3.17 E+054 8.87 E+054 <br /> Reference:Appendix 1,OEHHA Target Indoor Air Concentrations and Soil-Gas Screening Numbers for Existing Buildings under <br /> Residential and Industrial/Commercial land uses. <br /> Notes:1."Residential Land Use"screening levels generally considered adequate for other sensitive uses(e.g.,day-care centers, <br /> hospitals,etc.). <br /> CommerciaUndustnal properfies should be evaluated using both residential and commerciaVindustnal CHHSLs.A deed restriction <br /> that prohibits use of the property for sensitive purposes may be required at sites that are evaluated and/or remediated under a <br /> commerciallndustdal land use scenario only. <br /> Calculation of cumulative risk may be required at sites where multiple contaminants with similar health effects are present. <br /> Carcinogens:CHHSLS based on target cancer risk of 10-6.CaIEPA cancer slope factors used when available. <br /> Noncarcinogens:CHHSLS based on target hazard quotient of 1.0. <br /> Soil Gas: Screening levels based on soil gas data collected<1.5 meters(five feet)below a building foundation or the ground <br /> surface.Intended for evaluation of potential vapor intrusion into buildings and subsequent impacts to indoor-air.Soil gas data <br /> should be collected and evaluated at all sites with significant areas of VOC-impacted soil.Screening levels also apply to sites that <br /> owrie plumes of VOC-impacted groundwater. <br /> 3.Calculation of a screening number for the chemical has been postponed(pp)until the toxicity criterion currently being developed <br /> by OEHHA is published as a final document. <br /> 4.Representative Screening Numbers for mixed xylenes.The representative value for mixed xylenes is based on the calculated <br /> lowest one amongst the three isomers. <br /> April 2010 <br />