Air Quality and Transportation

Ground level ozone pollution and particle pollution can lead to unhealthy air quality in the Washington, D.C. area, especially in the summer months. Air quality is closely monitored, and air quality reports and forecasts are available from several sources.

Vehicle emissions are a major source of air pollution, which is one good reason to reduce driving, anytime. On days when the forecast is for unhealthy air quality, drivers can make an extra effort to avoid adding to the pollution.

People who walk or bike for transportation, and anyone else who spends time outdoors, can protect their health by checking the air quality report and forecast before they head out.

Ground Level Ozone

During the months of April through October, weather conditions in the Washington, D.C. area, along with pollutants in the air, can result in the formation of ground-level ozone. Ozone pollution is hazardous to human health and hazardous to the environment.

Vehicle emissions are a major source of the pollutants that form ground level ozone. On days when the level of ozone pollution is forecast to be high, it's more important than ever to reduce automobile pollution, as well as take other actions to reduce air pollution.

Particle Pollution

Particle pollution is also a serious problem in our area, and high levels can occur at any time of year. Small particles of dust, smoke, soot, and other pollutants in the air can penetrate deep into our lungs and adversely affect our health. Vehicle emissions are one source of particle pollution.

Air Quality Reports, Forecasts, and Alerts

Check these sites for forecasts, current conditions, and to sign up to receive email alerts.

Clean Air Partners

Clean Air Partners, a non-profit organization of Baltimore- and Washington-area government, environmental and business leaders, helps combat the problem of ground-level ozone and particle pollution by encouraging voluntary actions that reduce the amount of pollutants in the air, especially on days when weather conditions are favorable for ozone formation. These are generally hot (90+ degrees), sunny days with little or no wind and no precipitation.

Clean Air Partners has developed a color-coded system for communicating the expected level of ozone and particle pollution and corresponding health risks and suggested actions. Depending on the amount of pollution, each day during ozone season is rated Code Green (good), Code Yellow (moderate), Code Orange (unhealthy for sensitive groups), Code Red (unhealthy), or Code Purple (very unhealthy)

What is Ground-Level Ozone? Why is it a Problem?

Ozone is an invisible gas formed when volatile organic compounds (VOCs) and nitrogen oxides (NOx) “cook” in the presence of sunlight. Ozone can be good or bad, depending upon where it is located. Ozone in the upper stratosphere protects human health and the environment, but ground-level ozone can be harmful to both. Ground-level ozone is produced by the combination of pollutants from many sources, including smokestacks, motor vehicles, paints, lawn mowers, solvents and household products. Emissions from motor vehicles are the primary source of ozone-causing pollutants in this region, accounting for about 30-40% The second largest source is emissions from gasoline-powered lawn and garden equipment.

How Air Quality Affects Human Health

High concentrations of ozone can cause shortness of breath, coughing, wheezing, headaches, nausea, eye and throat irritation and reduced immune function. Long-term effects may include impaired lung function, scarring of lung tissue and worsening of lung-related diseases. People who suffer from lung diseases such as emphysema, pneumonia, and asthma have even more trouble breathing in polluted air. These effects can be more severe in children, the elderly and exercising adults. Children are more susceptible because they often play outside on hot, muggy days. Their lungs are still developing, and they breathe more rapidly and inhale more air pollution per pound of body weight than do adults. On days when ozone pollution is at it's worst, these factors put children at increased risk for respiratory problems.

Exposure to particles in the air can decrease lung function, weaken the heart, and possibly bring on a heart attack.

Environmental Effects of Air Pollution

Ground-level ozone interferes with the ability of plants to produce and store food. Therefore, growth, reproduction and overall plant health are compromised. By weakening vegetation, ozone pollution makes plants more susceptible to disease, pests and environmental stresses. Ozone smog has also been shown to reduce agricultural yields for many economically important crops. Over the years, the effects of ground-level ozone can affect whole forests or ecosystems. Nitrogen pollution (NOx) is harmful to waterways, such as the Chesapeake Bay and its rivers. Scientists have found that about 25% of the nitrogen entering the bay comes from the air.

Particles are the major source of haze, and can harm the environment by changing the nutrient and chemical balance in soil and water.

Transportation and Climate Change

In addition to producing pollutants that harm human health and the environment, vehicles burning gasoline and diesel fuel are a major source of greenhouse gases that contribute to global climate change. So while we're clearing the air by reducing the amount we drive, we may also be saving the planet. To learn more see AIRE: Arlington Initiative to Reduce Emissions.

Did You Know?

BikeArlington offers FREE confident cycling classes.

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