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Air Quality
What are Air Quality Action Days?
Air Quality Action Days are declared when ground-level ozone is predicted to exceed health standards.

On Air Quality Action Days, air quality is expected to reach unhealthy levels, Code Red or higher. The Clean Air Pyramid is a handy graphic representation rating air quality by color, ranging from green (good), through yellow, orange, red, and purple (very unhealthy). On Air Quality Action Days, individuals and employers alike can take easy and effective actions to reduce production of and exposure to air pollution.

The Air Quality Action Days program is sponsored by Clean Air Partners, a public/private partnership with representatives from business, government, and advocacy organizations in the Baltimore and Washington metropolitan regions. The Metropolitan Washington Council of Governments (COG) and the Baltimore Metropolitan Council actively support the program.

What is Ozone and Particle Pollution?
Ozone is an invisible gas that occurs both in the Earth's upper atmosphere, and at the ground level. It can be good or bad for your health and the environment depending on its location. The ozone in the Earth's stratosphere, or the "good" ozone, protects us from harmful ultraviolet (UV) rays. The ozone formed at ground level is "bad" because it makes the air unhealthy to breathe and damages crops, trees and other vegetation. It is formed when pollutants emitted by cars, power plants, chemical plants and other sources react chemically in the presence of sunlight. Ground-level ozone occurs during the summer months when sun and hot temperatures prevail. In our region, its highest concentration can be observed from May through September. Unlike ozone, particle pollution is not a seasonal pollutant, and can have high concentration anytime of the year. An average number of 10 Air Quality Action Days may be called during a year.

Air Quality Forecast
Ozone formation is influenced by the weather, so it is possible to predict when atmospheric conditions will most likely produce ground-level ozone. Expect a declaration when it's hot, sunny, stifling and there is little wind.

Weather forecasts and pollution monitors help experts predict future concentrations. A team of meteorologists from the Maryland Department of the Environment, the University of Maryland, and COG issue daily air quality forecasts for the following day. Information is then made available to the public through faxing and e-mail services, websites, hotlines and the media.

A color-coded system is used to rate the air quality and the health risk. Code Green is good, Code Yellow is moderate, Code Orange is unhealthy for sensitive groups, Code Red is unhealthy, and Code Purple is very unhealthy. When a Code Red or above is predicted, an Air Quality Action Day is declared. Clean Air Partners notifies participants via fax, e-mail, its website, and through the media.

Citizens can reduce their impact on air quality by reducing driving through carpooling, telecommuting or taking mass transit; refueling after dark; and postponing lawn and garden chores that use gasoline-powered equipment.

Employer Program
Employers are encouraged to join the Air Quality Action Days Employer Program, a workplace-based public outreach program sponsored by Clear Air Partners. When unhealthy air pollution is likely, Clean Air Partners will notify participants.

Employers are asked to inform employees and customers about the pending forecast and suggest voluntary actions that individuals can take to reduce ground-level ozone pollution.

On average, company program coordinators devote only 20 – 45 minutes per Air Quality Action Day to the program. Participants are encouraged to modify their company operations during Air Quality Days.

Actions that companies can take
  • Promote public transit or carpooling. Public transit is offered free or at reduced fare on Air Quality Action Days.
  • Allow employees to telework.
  • Refuel after dusk and limit driving.
  • Postpone mowing lawns with gasoline powered mowers.
  • Do not use oil-based paints.
For more information visit Clean Air Partners.

Air Quality Index Levels of Health Concern
Numerical Value
Air quality is considered good, and air pollution poses little or no risk.
  1. Keep engines tuned
  2. Conserve electricity, set AC to 78 degrees
  3. Use environmentally friendly products
Air quality may pose a moderate health risk, especially for those who are unusually sensitive to air pollution.
  1. Carpool, bike to work, use public transit or walk
  2. Limit driving, consolidation trips
  3. Reduce idling
Unhealthy for Sensitive Groups
Members of sensitive groups, children and adults with respiratory and heart ailments, may experience health effects and should limit time spent outside. The general public is not likely to be affected.
  1. Refuel after dusk, use fuel efficient vehicles
  2. Avoid driving, use transit, telecommute
  3. Avoid using aerosol products
Everyone may experience health effects and should limit their outdoor activity; members of sensitive groups may experience more serious health effects.
  1. Avoid lawn mowing or use an electric mower
  2. Avoid any gas powered lawn equipment
  3. Put off painting until air quality improves
Very Unhealthy
Everyone may experience more serious health effects and should avoid outdoor activities, especially individuals with heart and breathing ailments, children, and older adults.

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