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street improvements would result in a substantial decrease in the one -hour and <br />eight -hour average carbon monoxide concentration, below both federal and <br />state standards and lower than projected conditions for the "no- project" <br />alternative. Conversely, the state one -hour standard could be exceeded in <br />2006, if the improvements are not built. <br />Standard construction management measures will be followed to minimise <br />short-term, construction - related air pollutant emissions. In addition to the <br />proposed improvements, which will result in several beneficial effects on local <br />air quality, consideration will be given to the provisions of bus - turnouts, the <br />use of energy efficient street lighting, and synchronization of traffic signals to <br />further minimise long -term emissions. <br />Discussion <br />Two types of air pollutant sources must be considered with respect to the <br />proposed project: stationary sources and mobile sources. Stationary source <br />considerations include emissions on -site from construction activities as well as <br />emissions at the power plant associated with the electrical requirements of the <br />project. Mobile source considerations include exhaust emissions resulting from <br />short-term construction activities and long -term traffic changes associated with <br />the project. <br />Short-term impacts on air quality will occur during the construction activities <br />required to implement the proposed project. <br />These temporary impacts will include: <br />1. particulate (fugitive dust) emissions from construction activities on -site; <br />2. exhaust emissions from the construction equipment used on -site as well <br />as the vehicles used to transport the equipment to and from the site; <br />and <br />3. exhaust emissions from the motor vehicles of the construction crew. <br />On a short -term basis, large dust particles (30 -100 microns in diameter) that <br />settle to earth within a few hundred feet of the construction area could create <br />a temporary localized nuisance problem. Additionally, fine - grained particles <br />(less than 30 microns in size) may be emitted and dispersed over greater <br />distances, occasionally annoying adjacent receptors especially during Santa Ana <br />wind conditions. <br />An average particulate emission factor for heavy construction activities of 1.2 <br />tons of dust per month of activity per acre disturbed has been cited by the <br />rV -9 <br />75C -144 <br />