While there was no significant change in the ratio of polymeric to monomeric OPN in all subjects across exposures, in those with asthma, there was a significant decrease in the ratio of polymeric to monomeric OPN with increasing ozone exposure [PE±SEM of -14.5±8.9% (p = 0.01) and 10.7±12.0% (p = 0.81) change in ratio of polymeric to monomeric OPN per 100 ppb ozone for those with and without asthma, respectively] (Fig 5 parts D and E). The gene discussed is SPP1; the disease is asthma.