As a sign of the times, in addition to the morning traffic and weather reports, many large news networks are also reporting ground level ozone measurements as an index of air pollution. Ozone has long been known to induce respiratory inflammation, and excessively high levels of ozone can put the elderly or individuals with compromised respiratory function at risk for injury. Currently 0.1 parts per million (ppm) is the maximum ozone level allowed in key European cities; however, most typical US cities have levels ranging between 0.1 and 0.5 ppm, with cities such as Los Angeles reaching highs of 2.0 ppm.
At levels of 0.3 ppm the effects of extended ozone exposure become noticeable in healthy individuals, with predominate effects including headaches and throat irritation. As ozone levels rise symptoms can become more severe and include reduced lung function, reduced pulmonary immune function and an increased chance of mortality (see Ozone’s Effect on the Skin on Page 30).
In light of the effects of ozone pollution and the ever-increasing levels of ozone found in US cities, it should come as no surprise that 14 states have recently sued the US Environmental Protection Agency (EPA) in attempt to establish stricter laws regarding ozone pollution.
While most research regarding ozone exposure has focused on the respiratory system, there has been increasing interest in the effects of ozone exposure on the skin. Early work by Thiele et al.5 reported two effects of ozone exposure in mice: depletion of α-tocopherol and ascorbic acid, two key antioxidants in the superficial levels of the epidermis; and induction of lipid peroxidation throughout the epidermis (see Ozone Levels and Effects).
