For the 72-96 h integrated samples, a later re-examination of chromatography data utilizing mass spectrometry (MS) detection revealed some peak coelution that we were not aware of and did not consider in our original gas chromatography quantifications by flame ionization detection (FID). The coelution resulted in overestimation of selected peak areas and analyte mixing ratios, in particular for n-nonane and n-decane. Therefore, results that were presented from the 72-96 h integrated samples in Figures 3b, 4b, and 5, and Supplemental Tables S4, S6b, S8, and S10 are incorrect. New Figures 3b, 4b, and 5, considering reintegrated data, and with results for n-nonane and n-decane removed, are provided below. The new Tables S4, S6b, S8, and S10 are provided in the Supporting Information. Our overall findings and conclusions are unchanged. The following corrections should be made in the main text: Page 4519. The second paragraph under the Results and Discussion header should read as follows: For the 3, 72, and 96 h samples (Figure 3b and Table S6b), the TWA mean concentration from the 3 h samples collected in Platteville (247 m from nearest O&G facility) was compared to the mean concentration from the 72 and 96 h samples collected in Boulder (<1600 m from nearest O&G facility) and Eastern Boulder County (448-625 m from nearest O&G facility). Mean ambient benzene and ethylbenzene concentrations did not vary significantly between locations, although the lowest mean concentrations occurred in samples collected in Boulder. Mean ambient toluene, ethylbenzene, and total xylene concentrations in Platteville were 1.6-2.6 times higher than the mean concentrations in Boulder and Eastern Boulder County (p > 0.0001) (Figure 3b, Table S6b). Page 4519. The second paragraph under the Noncancer Hazards header should read as follows: Figure 4b presents chronic HQ and HI estimates based on TWA mean 3 h (Platteville) and mean 72-96 h (Boulder and Erie) sample results (Supporting Information Table S8). Total chronic HIs were highest in Platteville, where the total HI was 0.60, followed by Eastern Boulder County, and then Boulder. Nervous system, respiratory system, blood system, and developmental HIs were >1 for all locations. Page 4519. The last paragraph under the Lifetime Excess Cancer Risk Estimates should read as follows: Figure 5 presents lifetime excess cancer risks based on daily inhalation intake dose estimates calculated from 1 min, 3 h, and 72-96 h sample results (Supporting Information Tables S9 and S10). All cumulative lifetime excess cancer risks exceeded USEPA's de minimus benchmark of 1 in a million (as seen in ref 58 in the original article) with benzene representing more than 95% of the total risk estimate for all scenarios. The cumulative lifetime excess cancer risk increased with decreasing distance to the nearest O&G facility. For residents living within 152 m of an O&G facility, the risk exceeded the USEPA upper bound risk level of 1 in 10 000,56 with an overall risk of 8.3 per 10 000 (Supporting Information Table S9). The cumulative lifetime excess cancer risk was higher in Eastern Boulder County and Platteville than in Boulder and reached the USEPA's upper bound risk level of 1 in 10 000 at both locations, based on the (Figure Presented). 3, 72, and 96 h sample results (Supporting Information Table S10). For similar scenarios, the cumulative lifetime excess cancer risks based on mean 72-96 h sample results are greater than risks based on TWA mean 1 min and 3 h sample results.
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