Tropospheric Ozone - Health Effects

Health Effects

Ozone is known to have the following health effects at concentrations common in urban air:

• Irritation of the respiratory system, causing coughing, throat irritation, and/or an uncomfortable sensation in the chest.
• Reduced lung function, making it more difficult to breathe deeply and vigorously. Breathing may become more rapid and more shallow than normal, and a person's ability to engage in vigorous activities may be limited.
• Aggravation of asthma. When ozone levels are high, more people with asthma have attacks that require a doctor's attention or use of medication. One reason this happens is that ozone makes people more sensitive to allergens, which in turn trigger asthma attacks.
• Increased susceptibility to respiratory infections.
• Inflammation and damage to the lining of the lungs. Within a few days, the damaged cells are shed and replaced much like the skin peels after a sunburn. Animal studies suggest that if this type of inflammation happens repeatedly over a long time period (months, years, a lifetime), lung tissue may become permanently scarred, resulting in permanent loss of lung function and a lower quality of life.

A statistical study of 95 large urban communities in the United States found significant association between ozone levels and premature death. The study estimated that a one-third reduction in urban ozone concentrations would save roughly 4000 lives per year (Bell et al., 2004).

Tropospheric ozone causes approximately 21,000 premature deaths per year in 25 countries in the European Union. (WHO, 2008)