3_Exhibit B - Laserfiche WebLink

4/6 provided by the screening calculator are conservative, because the calculator was developed based on the 2011 version of the California Mobile EMission FACtors model (EMFAC), and EMFC has since been updated to reflect lower on-road emissions. The screening health risk impacts from roadway segments between 10,000 AADT and 30,000 AADT were combined with the impacts from all other sources at the Project’s location, and presented in Table 1. The combined impact from all the sources results in a cancer risk of 35 in 1 million, a chronic HI less than 0.1, and maximum annual average PM2.5 concentrations of 0.4 µg/m3 at the Project site, as shown in Table 1. These results did not take into any consideration of the Project’s building envelop and any ventilation and filtration system that would further reduce the indoor air quality impacts from ambient TAC concentrations. The cumulative health risk impacts would all be below the BAAQMD cumulative thresholds of significance; thus, the cumulative health risk impacts associated with the Project are less than significant. In addition to new residential receptors, the Project would also introduce new recreational receptors that would be exposed to ambient TAC concentrations in the proposed outdoor recreational spaces. The Project would include four recreational spaces: two ground-level courtyards, A and B, and two roof decks on the fourth and fifth levels, respectively. Courtyard A would be surrounded by buildings in all four directions; Courtyard B would be surrounded by buildings in three directions and would open to the drive aisle and the surface parking lot to the west. Courtyard A would be shielded from TAC emission sources in the vicinity of the Project. The same buffering effect applies to Courtyard B, though to a lesser extent. Vegetation planted in the Project’s setbacks and in the courtyards, such as trees and shrubs, would further contribute to the pollution buffering effects, for instance, by removal of ultrafine particulate matter through enhanced agglomeration and nucleation on leaves, and by blockage of particulate matter from local sources.9 Although the proposed roof decks would be less shielded by buildings and vegetations compared to the courtyards, they would be at least 50 feet above ground. The nearest TAC emission sources to the roof decks would be mobile sources on Stoneridge Mall Road, which has less than 10,000 AADT and is considered a minor impact source by the BAAQMD.10 The substantial vertical distances between the rooftop receptors and the ground-level TAC source would further attenuate the health risk impacts at these receptor locations. The combined shielding and buffering effects of buildings and vegetation, as well as attenuation by distance, would reduce the screening-level health risks presented in Table 1 for recreational receptors. Further, the new recreational receptors would not have the same exposure frequency as were developed for the residential receptors presented in the screening-level health risks in Table 1. It is generally assumed that recreational receptors would spend time in the recreational space for up to two hours a day. In contrast, residential receptors for which the health risk screening values in Table were derived are assumed to spend between 72 percent and 85 percent of time at home, consistent with the Office of Environmental Health Hazard Assessment Risk Assessment Guidelines, which would result in an exposure duration between 18 hours and 21 hours a day.11 The exposure duration of the recreational receptor is a fraction of the exposure duration of the residential receptors. Even though recreational receptors would have higher breathing rate during moderate intensity activities expected in recreational spaces compared to the sedentary and light intensity activities for residential receptors, 9 Diener et al, 2021. How can vegetation protect us from air pollution? A critical review on green spaces' mitigation abilities for air-borne particles from a public health perspective - with implications for urban planning. Science of the Total Environment, Volume 796, 148605, ISSN 0048-9697, available at: https://doi.org/10.1016/j.scitotenv.2021.148605. 20 November. 10 BAAQMD, 2012. Recommended Methods for Screening and Modeling Local Risks and Hazards. May. 11 Office of Environmental Health Hazard Assessment, 2015. Air Toxics Hot Spots Program, Risk Assessment Guidelines, Guidance Manual for Preparation of Health Risk Assessments. February.