Air Pollutants and Health Effects


Ground-level ozone, or “smog,” is caused when reactive organic compounds and oxides of nitrogen get “cooked” in the lower atmosphere by the sun’s ultraviolet rays. Ozone created in one part of the Bay Area can easily travel to other parts of the region due to local air currents and become trapped by geographical features like low-lying valleys.

Health Effects

Respiratory Irritation

Ozone can cause coughing, headaches, and eye, nose, and throat irritation. Symptoms may last for a few hours after ozone exposure and even become painful.

Reduced Lung Function

Lung function is based on the amount of air drawn in with a full breath and the speed at which it is exhaled. Ozone can make it more difficult to breathe as deeply and quickly as normal.

Asthma Aggravation

When ozone levels are high, more people have asthma attacks. Ozone makes people more sensitive to allergens, such as dust mites, pets, and pollen, which are the most common triggers of asthma attacks.

Lung Lining Inflammation and Damage

Ozone’s effect on the lining of the lung is similar to that of a sunburn on the skin. It damages the cells that line the air spaces in the lung. Within a few days, however, the damaged cells are usually repaired, just as skin recovers from sunburn naturally.

Long-Term Effects

Most of the health effects of ozone are considered short term as they eventually cease once ozone levels subside. However, there is evidence that repeated short-term damage from ozone exposure may permanently injure the lungs. Other studies in heavily polluted areas have linked prolonged exposure to ozone to the development of asthma in children.

Environmental Effects

Ozone pollution also has environmental effects of ozone. These include:

  • Compromised growth, reproduction, and overall health of plants. Ozone interferes with the ability of plants to produce and store food. This also makes plants and trees weaker and more susceptible to diseases, pests, and environmental stresses.
  • Damage or death of leaves so that they become spotted or brown or fall off prematurely.
  • Reduction of agricultural yields for many economically important crops, including soybeans, kidney beans, wheat, and cotton.

Scientists believe that the impacts of ground-level ozone on long-lived species – such as trees – add up over many years, so that whole forests or ecosystems can be affected.