Outdoor Air Quality

What is Ozone?

Ozone occurs naturally in the upper atmosphere and shields the earth from solar radiation. But when it occurs at ground level, ozone is one of the most dangerous of the common air pollutants, or criteria pollutants. It is the primary component of smog. Although ozone concentrations have gone down in recent years, ozone is still considered a major problem for all urban areas, both large and small.

Ozone is not emitted to the air directly; rather, it is formed by chemical reactions in the air. The two pollutants that form ozone are hydrocarbons (or byproducts of combustion) and nitrogen oxides. Because energy from the sun is needed for these chemical reactions to occur, high ozone concentrations usually occur in the summer.

The Connecticut Department of Environmental Protection operates 12 ozone-monitoring stations in Connecticut, but no stations are located in the city of Hartford. The closest station is located in East Hartford at McAuliffe Park.

What are the sources of ozone?

Like most other pollutants, ozone-producing chemicals come primarily from cars, trucks, and buses. These vehicles are the largest sources of the nitrogen oxides and produce more than 30% of the hydrocarbons that contribute to ozone. Significant amounts of ozone-producing chemicals come from industrial uses and coal power generation.

The pollutants that cause ozone can be transported by wind hundreds of miles from their sources. Thus, ozone-producing chemicals in Hartford can actually originate in the Midwest.

The EPA air quality standard for ozone is 0.12 part per million for a 1-hour average and 0.08 parts per million for an 8-hour average. The 8-hour average is more restrictive than the 1-hour average because the concentrations vary during the day. It is similar to what people are being exposed to throughout the day. This means that that the average concentration over 1 hour cannot be higher than 0.00000012 parts ozone per 1 part air and the average over 8 hours cannot be higher than 0.00000008 parts ozone per 1 part air.

To help simplify things, the EPA has developed an Air Quality Index (AQI) to rate the overall air quality and the citizens of greatest risk. The AQI takes into account the concentration of five air pollutants, including ozone and fine particulate matter. AQI for Hartford.

What are the health effects of ozone?

When ozone is present at ground level, short-term and long-term exposures have been associated with a number of adverse health effects:

Increased hospital and emergency room visits for respiratory problems have been linked to high ozone concentrations.

Outdoor ozone can move indoors, especially if windows are open and no air conditioning is used. If ozone levels are high, people should limit both outdoor and indoor activities. If the weather is hot, people should spend more time in a cool environment, preferably one that is air-conditioned. Sensitive individuals, including the elderly, children, and people with asthma, must be especially careful.

How do ordinary activities contribute to ozone?

Many ordinary day-to-day activities contribute to ozone in the environment. The greatest sources of ozone in the environment are personal and commercial vehicles. Greater use of public transportation, carpooling, and more fuel-efficient vehicles would help to reduce the amounts of dangerous substances added to the environment.

Reducing electricity consumption would help to reduce pollution from power production.

 

Hartford's ozone concerns

The Connecticut Department of Environmental Protection operates 12 ozone-monitoring stations in the state, but no stations are located in the city of Hartford. The closest station, located in East Hartford at McAuliffe Park, is considered representative of the city of Hartford.

An EPA website, AIR/NOW,  provides an ozone forecast for the next day for the Hartford area.

Hartford's ozone concentrations are similar to those in other urban areas in Connecticut. In 1996 Hartford did not exceed ozone standards. In 1997, ozone concentrations in Hartford were greater than the 1-hour standard two times, in 1998 one time, and in 1999 only two times. In 2000, ozone concentrations in Hartford did not exceed the 1-hour ozone standard.

Number of Ozone Exceedences
Hartford and Other Connecticut Areas 1997

Location
Number of Days Levels Exceeded 8-hour Standard 1997
Number of Days Levels Exceeded 8-hour Standard 1999
Number of Days Levels Exceeded 8-hour Standard 2000
Hartford/ East Hartford
7
11
3
Danbury
14
17
7
Greenwich
13
14
3
Stratford
17
9
4
Torrington
9
13
4