Does Los Angeles affect San Diegos air quality?
Smog transported from the South Coast Air Basin (the metropolitan areas of Los Angeles, Orange, San Bernardino, and Riverside Counties) is a key factor on more than half the days San Diego exceeds clean air standards. Ozone and precursor emissions are transported to San Diego during relatively mild “Santa Ana” weather conditions. Winds blowing toward the southwest transport South Coast’s polluted air out over the ocean, and the sea breeze brings it onshore into San Diego County. (During a strong Santa Ana, pollutants are pushed far out to sea and miss San Diego.) When the transported smog is at ground level, the highest ozone concentrations are measured at coastal and near-coastal monitoring sites. When the blown-in smog cloud is elevated, coastal sites may be passed over, and the transported ozone is measured further inland and on the mountain slopes.
