Ozone concentrations for the California South Coast Air Basin predicted by the Caltech research model show a large region in which the national ozone standard of 120 parts per billion (ppb) are exceeded. Measurement data corroborate these predictions. Scientific studies have shown that human exposure to ozone concentrations at or above the standard can impair lung functions in people with respiratory problems and can cause chest pain and shortness of breath even in the healthy population. This problem raises concern since more than 30 urban areas across the country still do not meet the national standard. |