Health Effects of Photochemical Oxidants

Ozone toxicity occurs in a continuum in which higher concentrations, longer exposure duration's and greater activity levels during exposure cause greater effects. Ozone has the greatest impact on the respiratory system, where it irritates the mucous membranes of the nose, throat and airways. Symptoms associated with exposure include cough, chest pain, and throat and eye irritation. Ozone can also increase susceptibility to respiratory infection. Acute adverse effects may impair normal functioning of the lungs and induce respiratory inflammation. Healthy individuals who exercise heavily for brief periods (1 to 2 hours) may experience respiratory symptoms at levels exceeding the Hong Kong Air Quality Objective of 240 microgrammes per cubic metre. They may also experience these symptoms at a lower concentration for longer exposure (6 to 8 hours) during moderate exercise. Individuals with sensitive respiratory systems (such as with asthma or respiratory disease) are more susceptible to the effects of ozone.

Other photochemical oxidants, such as peroxyacyl nitrates and aldehydes, are associated with eye irritation.