Laserfiche WebLink
possible that some homes built after January 2014 were constructed of materials that were purchased prior <br />to this deadline. Therefore, contrary to Mr. Offermann's statement, the HENGH study does not establish - <br />nor could it establish - that median indoor formaldehyde concentrations in new homes built with CARB <br />Phase 2 ATCM materials are 22.4 tag/m3 or 18.2 ppb. <br />Next, Mr. Offermann further embellishes the results of the HENGH study by applying what he terms is a <br />"correction" to the study's 22.4 tag/m3 (18.2 ppb) median indoor formaldehyde concentration finding, thereby <br />resulting in a "true" median indoor formaldehyde concentration of 24.1 pg/m3. He states that "formaldehyde <br />concentrations in the HENGH study were measured with passive samplers, which were estimated to under - <br />measure the true indoor formaldehyde concentrations by approximately 7.5%." In the paper by Singer et al. <br />that is cited by Mr. Offermann, the authors note that Offermann (this commenter) and Hodgson "have shown <br />that sampling rates for... passive monitors start to drop sharply when air velocity falls below about 75 <br />[centimeters per minute]." However, the study subsequently acknowledges other household research that <br />reports how "such low air velocities were infrequent." The authors then reason that "it is possible that <br />sampling rates could have been lower than the assumed standard values at some times in some homes," <br />but concede that the HENGH study "did not measure velocities around the passive samplers" or "verify <br />measured concentrations with pumped samples." Thus, by the study's own admission, there is no evidence <br />that low air velocities were ever a factor during passive sampling of indoor formaldehyde levels. Contrary to <br />Mr. Offermann's statement, the application of a 7.5% "correction" is not evident anywhere in the paper by <br />Singer et al. Where the paper reports its findings, it reports the 18.2 ppb figure, which correlates with Mr. <br />Offermann's original 22.4 tag/m3 figure - not his "corrected" 24.1 tag/m3 figure (See Exhibit 1). <br />Exhibit 1 <br />HENGH Study Median Formaldehyde ("HCHO") Concentrations <br />Table 3. Time -averaged pollutant concentrations in California homes built 2011-2017 (HENGH, <br />current study) and 2002-2005 (CNHS, Offermann, 2009). <br />Location <br />HCHO <br />(pph) <br />PM2.5 <br />{µglm3} <br />NO2 <br />(pph) <br />CO2 <br />(PP-) <br />Statistic <br />HENGH <br />CNHS' <br />HENGH <br />CNHS' <br />HENGH <br />CNHS' <br />HENGH <br />CNHS` <br />Indoor <br />N=68 <br />N=105 <br />N=67 <br />N=28 <br />N=66 <br />N=29 <br />N=69 <br />N=107 <br />Mean <br />19.8 <br />18.2 <br />13-28 <br />35.0 <br />29.3 <br />11-70 <br />7.5 <br />4.8 <br />1.6-16 <br />13.4 <br />10.5 <br />6.0-31 <br />5.8 <br />4.5 <br />1.1-12 <br />5.2 <br />1.6 <br />1.4-12 <br />620 <br />608 <br />481-770 <br />610 <br />564 <br />405-990 <br />Median <br />iwh-90`h <br />Outdoor <br />N=66 <br />N=39' <br />N=67' <br />N=11' <br />N=65 <br />N=114 <br />No data <br />No data <br />Mean <br />2.2 <br />L9 <br />9.3, 10.5 <br />7.9 <br />5.4 <br />2.1 <br />Median <br />2.3 <br />1.7 <br />6.8, 9.7 <br />9.7 <br />3.6 <br />1.5 <br />Iwh-90'h <br />1.4-3.1 <br />0.6-2.8 <br />5.0-10 <br />0.1-11 <br />1.4-1.7 <br />5.3-16.7 <br />As indicated in the red box, Singer et al. reports that median formaldehyde concentrations in <br />HENGH study homes were 18.2 ppb, which correlates with Mr. Offermann's original 22.4 <br />pg/m3 concentration, not his "corrected" 24.1 pg/m3 figure. (Singer et al.) <br />Page 3 <br />