Ozone Action Day

An OZONE Action Day, which can be declared by a local municipality, county or state, is observed at certain times during the summer months, when weather conditions (such as heat, humidity, and air stagnation) run The Risk of causing health problems.

Ozone Action Days primarily center in the midwestern portion of the United States; particularly in well-urbanized areas such as Chicago, Cleveland, and Detroit.

Ground ozone vs. Atmospheric ozone

Although the ozone levels found on the ground are the same chemical composition as those found in the ozone layer, they are not necessarily a byproduct of a thinning ozone layer in Earth's atmosphere. The upper-level layer protects people from the sun's most damaging ultraviolet rays, and helps to keep the climate of the Earth manageable for humans.

Ground-level ozone, however, is a health hazard. It is formed through a complex chemical reaction involving hydrocarbons, nitrogen oxides and sunlight on calm summer days where the weather may also be warm and humid 1. High levels of ground ozone affects the breathing process and aggravates asthma in chronic sufferers. The young, elderly, and those with lung diseases are especially suspectible.

Ozone is most likely to exceed safety limits from May through October when seasonal heat and sunlight are at their highest 2. However, similar conditions can occur at other times of the year in specific urbanized areas; namely the Los Angeles area, which is well-known for smog formation.

Sources of ground ozone

Since the majority of Ozone Action Days occur in the Midwestern United States, a major cause of the conditions are due to pollutants in the air released by heavy industry (manufacturing plants, refineries, coal-fired power plants). In recent years, many sites have taken steps to help reduce the amount of pollutants they discharge.

Secondary sources include automotive emissions (leaky auto exhaust systems, excessive engine idling) and liberal use of household chemicals or sprays. It is believed that nearly fifty percent of pollutant ozone molecules are attributed to the presence of these 3.

Notification

State, county, and even local governments can announce Ozone Action Days as much as a day in advance through the monitoring of approaching weather conditions and the Air Quality Index (AQI). The AQI is divided into six levels: the higher the number (on a 0-300 scale), the more severe the ozone threat 4.

What can be done

Heavy industries make up a high percentage of pollutants causing ground ozone. Without drastically altering or eliminating industrial production in an area altogether, air quality improvements are very slight, though noticeable. Non-industrial pollutants, while not thought of to be a major pollutant group, can be more controlled with more positive change occurring.

Basic steps in limiting ground ozone during Ozone Action Days are:

  • Controlling of auto emissions
    • Eliminate excessive engine idling
    • Ensure automotive exhaust system functions properly
    • Avoid unnecessary driving whenever possible
    • Don't gas up until after 6:00 pm
  • Limit the use of lawn mowers and outdoor grills to after 6:00 pm
  • Limit the use of aerosol cans around the home (for example, hair gel instead of hair spray)
  • Top Ten Tips for Ozone Action Days - provided by smartcommute.org
  • Vast link page to various world-wide sites on general air pollution, pollution monitoring, and the environment - courtesy Louisville (KY) Metro Air Pollution Control District