Diesel exhaust particles have been implicated in human allergic diseases by enhancing the production of IgE antibodies.38,39 We reported previously that serum hyaluronate levels were increased in children who lived near busy roads compared with those who lived farther away, but only among children in whom serum IgE levels had been elevated.5 Hyaluronate is considered to serve as a possible biomarker for lung diseases, and our results suggest that children with an atopic predisposition may be susceptible to the effects of automobile exhaust. This evidence concerns the gene IGHE and allergic disease.