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5.ENVIRONMENTAL CHECKLIST MOUNTAIN HOUSE NEIGHBORHOODS KAND L INITIAL STUDY 3.AIR QUALITY AND GREENHOUSE GAS EMISSIONS Guide for Assessing and Mitigating Air Quality Impacts(GAMAQI]l,was later updated in 2002. In the guidance document,the SJVAPCD has established the standards of significance for evaluating project air quality impacts(SJVAPCD, 2002) A project impact would be significant if: ■ A project results in estimated carbon monoxide concentrations exceeding the California Ambient Air Quality Standard of 9 parts per million (ppm) averaged over 8 hours and 20 ppm for 1 hour; ■ A project results in new direct or indirect emissions of ozone precursors (ROG or NOx) in excess of 10 tons per year; ■ A project has the potential to frequently expose members of the public to objectionable odors;or ■ A project has the potential to expose sensitive receptors(including residential areas)or the general public to substantial levels of toxic air contaminants. For construction impacts,the pollutant of greatest concern to the SJVAPCD is PM10.3 The SJVAPCD recommends that impact significance be based on a consideration of the control measures to be implemented during project construction.(SJVAPCD,2002). Compliance with Regulation VIII, Rule 8011, and e implementation of appropriate mitigation measures to control respirable particulate matter(PM10)emissions are considered by the SJVAPCD to be sufficient to render a project's construction-related impacts less than significant. The SJVAPCD GAMAQI contains a list of feasible control measures for construction-related PM10 emissions. Although the SJVAPCD GAMAQI recognizes that PM10 is a major air quality issue in the air basin, it does not establish quantitative thresholds for potential impact significance. However,for the purposes of this analysis, a PM10 emission of 15 tons per year from project operations is used as a significance threshold. Fifteen tons per year is the SJVAPCD threshold level at which new stationary Q sources requiring SJVAPCD permits must provide emissions"offsets."This threshold of significance for PM10 is consistent with the establishment of the ROG and NOx thresholds of 10 tons per year, which are also offset thresholds established in SJVAPCD Rule 2201, Setting — Greenhouse Gases Gases that trap heat in the atmosphere are called greenhouse gases(GHGs). The accumulation of GHGs in the atmosphere has been linked to global climate e change. Global climate change is a change in the average weather conditions on 3 Construction equipment emits carbon monoxide and ozone precursors.The SJVAPCD has determined that these emissions would cause a significant_air quality impact only in the case of a very large or very intense construction project(SJVAPCD,2002). (srrn ii 5-28