Ozone

VOC + NO_x + Sunlight = Ozone

Ozone is a pungent-smelling, colorless gas produced in the atmosphere when nitrogen oxides and volatile organic compounds (VOC) chemically react under sunlight. The highest ozone levels occur on hot summer afternoons.

Good up high, bad nearby.

Upper atmosphere ozone protects the earth from harmful radiation, but ground-level ozone (commonly known as smog) is unhealthy. Exposure to ground-level ozone can reduce lung function, cause respiratory irritation, aggravate asthma symptoms, and weaken the immune system. Ozone has environmental impacts as well; studies show that ozone can damage agricultural crops and forests.

How is the ozone in our region?

The Puget Sound area has not violated national ambient air quality standards for ozone since 1992, and in 1996 our region was designated as “attainment” status. Since this time, however, ozone levels have not decreased significantly, and concentrations often exceed the standard a few times each summer. The Department of Ecology monitors ozone levels in summer months.

What contributes to ozone?

The bulk of our ozone-causing nitrogen oxides and VOCs come from the transportation sector – emissions from cars and light trucks, marine vessels, and heavy-duty diesel vehicles. Other sources include gasoline-powered yard equipment such as lawn mowers, leaf blowers and trimmers; gasoline refueling; industrial solvents; and auto-body paint shops, among others.

What can be done to reduce ozone?

With most ozone caused by emissions from our tailpipes, choices we make about what we drive, how often and far we drive, and the kind of fuel we use can make a difference. Opting for manual or electric yard and recreation equipment, not topping off at the gas pump, and being mindful of the VOC content in products we buy also help.

For more on ozone:

• Ozone fact sheet (PDF 0.1MB)

• 2005 Air Quality Data Summary (PDF 1.2MB)

Did you know?

Spilling a shot-glass (1 oz) of gasoline creates the same amount of smog-forming VOC compounds as driving a car 25 miles