The Dangers of Ozone

Ozone and Health

Ozone, or ground-level ozone, is a pollutant that can be dangerous to health. In the continental U.S., ozone levels were above the 8-hour ambient air quality standard in most counties in 2009. Here's a map of the U.S. counties with high ozone levels in 2009. The map colors are based on the categories of the Air Quality Index. Purple, red, and orange areas exceeded the ozone standard in 2009.

Ground-level Ozone

Ground-level ozone is a substance that can be found in the atmosphere. It is also known as surface-level ozone and tropospheric ozone. It has an average concentration of 20 to 30 parts per billion by volume, but can reach 100 parts per billion in polluted areas.

Sources and Locations of Ground-level Ozone

Ground-level ozone is caused by several sources. Car exhaust, industrial boilers, motorized lawn equipment, and power plants are major contributors. Ground-level ozone is usually higher in urban areas. In Arizona, the most significant concentration is in Maricopa County. However, the pollutant can easily cross into rural areas. In rural areas, ground-level ozone is a significant health threat.

Formation of Ground-level Ozone

The formation of ground-level ozone is dependent on a number of factors, including low wind speeds and cloud cover. With these factors in place, it's possible to form harmful concentrations of ground-level ozone. However, the majority of air pollution containing ground-level ozone comes from private citizens. Motor vehicle emissions are the most common contributor.

Reducing Ozone in the Air

Fortunately, there are ways to reduce the amount of ozone in the air. You can start by checking the EPA Air Quality Index (AQI), which will let you know if the air quality is safe to breathe. Check it before you go outside, and plan your activities accordingly. If the AQI is high, you'll want to stay indoors.

Health Effects of Ozone Exposure

Recent studies have reported that ozone exposure is linked to a higher risk of mortality, including cardiovascular disease and respiratory problems. These studies used a standard analytical protocol to estimate ozone concentrations in air. They also accounted for other factors, such as the presence of particle pollution. Although the effects of ozone exposure on mortality are not entirely clear, they are consistent across age groups.

Recommended Limits and Impact on Respiratory Health

The World Health Organization (WHO) recommends a limit of 100 micrograms per cubic meter of air for health benefits. However, the European Union, the United States, and China have adopted different levels. Therefore, it is important to find a safe level that will protect the public.

Exposure to ozone can increase respiratory symptoms and may cause asthma attacks. Individuals with respiratory conditions are more susceptible to the adverse effects of ambient ozone, and they may require medication and emergency room visits to cope with symptoms. However, in most cases, these effects will subside or disappear within 48 hours.

Potential Toxic Compounds

Ozone exposure is believed to increase the formation of secondary organic and inorganic PM in indoor and outdoor environments. The compounds produced by the reaction of ozone with common indoor volatile organic compounds are believed to irritate respiratory systems. As such, the field is preparing to perform whole animal and human exposure studies to determine the toxicity of these compounds.