Aeroallergens of Southern California

Abstract

Southern California may have the widest variety of hayfever-producing plants in the United States. In Orange County, we found olive pollen to be the most prevalent and allergenic of the trees. Elm, ash, mulberry, and oak are also frequently identified and are major sources of pollenosis. Tree pollen is most prevalent from January through June except for Chinese elm, which pollenates from summer through fall. Two weed seasons are found in southern California, one from March through July and another from September through October. Russian thistle causes more positive skin test responses than any other weed pollen among atopic patients in Orange County. However, grass is the most frequently reactive pollen overall. Bermuda, rye, orchard, June, and brome are among the important grasses found in this area and produce a pollen peak from March through September. Cladosporium , basidiospores, Alternaria , smut, and ascospores are the most commonly identified outdoor spore types in Orange County. Cladosporium, Penicillium , and Alternaria are among the most dominant isolates inside southern California homes. Indoor mold growth can provide heavy exposure to unusual spore types such as Torula herbarum and Stachybotrys. Prompt attention to water problems indoors can prevent much mold overgrowth from occurring. Alternaria, Drechslera, Curvularia , and Phoma are the most common causes of positive skin test reactions among mold-sensitive patients in Orange County. Mold spores are prevalent all year but are highest in the fall. Because of the mild climate and varied flora in southern California, pollen and mold spore aeroallergens play an important role throughout the entire year.