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U primary source of CO emissions in most areas. Ozone is not directly emitted but is formed by a photochemical reaction in the atmosphere. Ozone precursors, reactive organic gases (ROG), and oxides of nitrogen (NOx) react in the atmosphere in the presence of sunlight. Ozone is a respiratory irritant and oxidant. The State's one-hour standard is 0.09 ppm, and the eight-hour standard is 0.8 ppm. Particulate matter forms on particles small enough to reach the lungs when inhaled. The State standard is 10 microns or less in diameter (PM-10). PM-10 conditions in San Joaquin County generally result from a mix of rural and urban sources, including agricultural burning and tilling, industrial emissions, dust suspended by vehicular traffic, and secondary aerosols formed by reactions in the atmosphere. San Joaquin County is a nonattainment area for the State's ozone and PM-10 standards. ROG, NOx, and PM-10 emissions during construction were analyzed, and the impact is less than significant. The use of dust control measures during construction will help mitigate PM-10 impacts. For the 2015 project with Phase 1 and Phase 11 interchange improvements, increased ozone precusors and PM-10 emissions exceed the State standards. This impact is significant and unavoidable. Trip reduction measures will reduce the impact but not below the level of significance. A Finding of Impact and Statement of Overriding Consideration have been prepared. Noise The State has established noise standards that govem the operation of aircraft and aircraft engines for all airports. The regulations designate the community noise equivalent level (CNEL) in decibels (db) as the noise rating method to be used at airports and define CNEL 65 db as the acceptable noise level for residents in the vicinity of an airport. The Health and Safety chapter of the General Plan designates 65 dB Ldn (day-night average sound level) or less for residential development and 60 dB Ldn or less for schools, group care facilities, and hospitals. Further, the General Plan (Implementation Measure 6) provides for mitigation through avigation easements and sound proofing of structures to reduce noise to 45 dB Ldn for new residential structures in the 65 db Ldn contours of a public access airport. The Federal Interagency Committee on Noise (FICON) recommends that a significant airport noise impact should be identified when an increase in noise of 1.5 dB or more occurs and the projected sound level is 65 dB DNL or above, or if there is an increase in noise of 3 dB or more and the project's sound level is between 60 and 65 dB DNL. Implementation of the proposed project would result in increased noise levels during construction. However, no noise sensitive uses occur within several thousand feet of the airport, and no noise sensitive land uses would be exposed to excessive construction noise. The projected 2015 aircraft noise exposure conditions with implementation of the proposed project would not result in an increase in aircraft noise of 1.5 dB over any noise sensitive land uses located within the 60 dB CNEL or above noise contours. The 2015 project with Phase I and Phase 11 interchange improvements (flyover ramps) results in increased surface traffic noise. However, direct traffic noise impacts of the project are considered less than significant because the project related increase would be less than 3 dB (i.e., barely perceptible) at residential areas. Further, the proposed land uses are commercial and industrial, which are not sensitive noise receptors. Significant cumulative traffic noise impacts are expected to occur at residential locations along Airport Way, both north and south of the airport, and along State Route 99, north of Arch- Airport Road. There is no feasible mitigation, and a Statement of Overriding Consideration has been prepared. San Joaquin County ER-96-1, et al\Stockton Airport Community Development Page 18