Air Monitoring 

The Western North Carolina Regional Air Quality Agency operates 4 monitors in Buncombe County. There is one ozone monitor and three PM2.5 monitors that are operated in accordance with EPA requirements. Air Monitoring is an important part of protecting the health of the citizens of Western North Carolina.

Ozone Monitoring

Ozone is a highly reactive form of oxygen. An ozone molecule is composed of three oxygen atoms (O3), instead of the two oxygen atoms in the molecular oxygen (O2) that we need in order to survive. In the upper atmosphere (stratosphere), the protective ozone layer is beneficial to people because it shields us from the harmful effects of ultra-violet radiation. However, ozone in the lower atmosphere (troposphere) is a powerful oxidizing agent that can damage human lung tissue and the tissue found in the leaves of plants.

Ozone is formed in the lower atmosphere primarily by nitrogen oxides (Nox) reacting with volatile organic compounds (VOCs) on warm, sunny days. Nitrogen oxides are released into the atmosphere as a by-product of combustion. For example, nitrogen oxides are released from the burning of vegetation during a fire. However, internal combustion engines and coal-fired power plants are the main sources of nitrogen oxides in the eastern United States. VOCs, or hydrocarbons, also come from man-made sources such as cars, service stations, dry cleaners, and factories, as well as from natural sources such as trees and other vegetation.


PM 2.5 is particulate matter that is smaller than 2.5 microns. Particulate matter may include solid, liquid or gaseous particles that vary in size and composition, and are suspended in the air. It may be emitted directly into the air from various processes, or, like ozone, may be formed by chemical reactions in the atmosphere. Awareness of the role that particulate matter pollution plays on our health has evolved over the years as scientific research has advanced. In the 1970s, particulate matter pollution was generally referred to as total suspended particulate (TSP). However, in 1987 the U.S. EPA replaced the TSP National Ambient Air Quality Standard with one for PM10, to reflect the serious health consequences of inhaling the smaller particles. In 1997, because of increasing evidence of the health threat from even smaller particles, the EPA added a new standard for PM2.5.

PM10 consists of those particles that have a diameter of between 2.5 and 10 microns. These so-called coarse particles are generally solid and liquid droplets, and are usually emitted directly into the atmosphere. Man-made sources of PM10 include road dust, combustion processes, and crushing and grinding operations. Coarse particles are inhalable, and are capable of accumulating in the upper respiratory tract. These particles can aggravate respiratory conditions such as asthma, emphysema and chronic bronchitis.

As bad as PM10 may be for our health, the consequences of breathing air laden with PM2.5 can be devastating. Fine particulate matter consists of particles that have a diameter of less than 2.5 microns. These ultra small particles are usually found in the gaseous state, and are generally formed by chemical reactions in the atmosphere between primary pollutants such as sulfur dioxide, oxides of nitrogen, and ammonia. The sources of these pollutants include coal and other fuel combustion, metal processing, and farming activities.

Fine particulate matter gets deposited deep in the crevices of our lungs, where it can accumulate and inflict havoc on our health. Inhaling even small concentrations of PM2.5 has been linked to chronic respiratory disease, aggravated asthma, decreased lung function, and increased mortality. The very young and the very old, as well as those with preexisting cardiopulmonary diseases, are most sensitive to particulate matter effects. When exposed to fine particulate matter, people with existing heart or lung disease are at an increased risk for hospitalization and premature death. Adverse health effects have been associated with exposures to particulate matter over both short periods and longer time frames.