Ozone-Related Respiratory Morbidity in a Low-Pollution Region.

Abstract

We evaluated the effects of ozone on respiratory-related hospital admissions in three counties in Washington State from 1990 to 2006. We further examined vulnerability to ozone by key demographic factors. Using linked hospital admission and ambient monitoring data, we estimated the age-, sex-, and health insurance-stratified associations between ozone (0 to 3 days' lag) and respiratory-related hospital admissions in King, Spokane, and Clark County, Washington. The adjusted relative risk (RR) for a 10 ppb increase in ozone at 3 days' lag was 1.04 (95% confidence interval [CI]: 1.02, 1.07) for Clark County, 1.03 (95% CI: 1.01, 1.05) for Spokane County, and 1.02 (95% CI: 1.01, 1.03) for King County. There was consistent evidence of effect modification by age. Ozone at levels below federal standards contributes to respiratory morbidity among high-risk groups in Washington.