Through collaboration with the Southern California NIEHS Center, Dr. Cass' research group at Caltech has embarked on a long-term study of the nature of man-caused emissions of allergens to the atmosphere and their resulting atmospheric concentration. The group has developed immunoassay techniques for the detection of latex allergens in environmental samples and applied those methods to the study of latex proteins that are extractable from authentic tire dust samples and from airborne particle samples. The group has undertaken a study of the allergen content of paved road dust emissions that occur as vehicle traffic moves over the streets. The investigators found more than 20 allergens associated with molds and pollen fragments in paved road dust samples collected in Southern California, and up to approximately 12% of the allergen concentrations in the atmosphere of some communities are contributed by paved road dust emissions. This may help to explain persistent reports of increased asthma incidence among persons living close to heavily-traveled streets. A companion study of allergen concentrations in woodsmokes is also underway.

In addition to the above research that deals directly with the biological consequences of air pollutant exposure, research into the physics and chemistry of photochemical smog and fine particle formation continues. The group is in the process of analyzing data from several field experiments conducted in 1996 and 1997 directed at observing fine particle size and composition evolution at the single particle level within air parcels crossing the Los Angeles Basin in the presence of gas-to-particle conversion processes. Mathematical models that relate source emissions to ambient air quality are being tested against these field experimental data.

Data from allergen studies, analytical assistance with elemental and organic carbon particle measurement, and expertise in the chemical description of air pollution problems are being supplied to the USC Children's Health Study through collaboration in the NIEHS Center. The research at Caltech represents a collaboration between Dr. Cass of the EARC and the Respiratory Disease Core members. The collaborative efforts will continue with Dr. Cass, who is now at Georgia Institute of Technology.