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Besides being a human carcinogen, formaldehyde is also a potent eye and respiratory <br />irritant. In the CNHS, many homes exceeded the non -cancer reference exposure levels <br />(RELs) prescribed by California Office of Environmental Health Hazard Assessment <br />(OEHHA, 2017). The percentage of homes exceeding the RELs ranged from 98% for the <br />Chronic REL of 9 µg/m3 to 28% for the Acute REL of 55 µg/m3. <br />The primary source of formaldehyde indoors is composite wood products manufactured <br />with urea -formaldehyde resins, such as plywood, medium density fiberboard, and particle <br />board. These materials are commonly used in residential building construction for flooring, <br />cabinetry, baseboards, window shades, interior doors, and window and door trims. <br />In January 2009, the California Air Resources Board (CARB) adopted an airborne toxics <br />control measure (ATCM) to reduce formaldehyde emissions from composite wood <br />products, including hardwood plywood, particleboard, medium density fiberboard, and also <br />furniture and other finished products made with these wood products (California Air <br />Resources Board 2009). While this formaldehyde ATCM has resulted in reduced emissions <br />from composite wood products sold in California, they do not preclude that homes built <br />with composite wood products meeting the CARB ATCM will have indoor formaldehyde <br />concentrations that are below cancer and non -cancer exposure guidelines. <br />A follow up study to the California New Home Study (CNHS) was conducted in 2016-2018 <br />(Chan et. al., 2018), and found that the median indoor formaldehyde in new homes built <br />after the 2009 CARB formaldehyde ATCM had lower indoor formaldehyde concentrations, <br />with a median indoor concentrations of 25 µg/m3 as compared to a median of 36 µg/m3 <br />found in the 2007 CNHS. <br />Thus, while new homes built after the 2009 CARB formaldehyde ATCM have a 30% lower <br />median indoor formaldehyde concentration and cancer risk, the median lifetime cancer risk <br />is still 125 per million for homes built with CARB compliant composite wood products <br />which is more than 12 times the NSRL 10 in a million cancer risk. <br />Assuming that the residential dwelling units for this project are constructed with CARB <br />3 <br />75E-259 <br />20 <br />21 <br />