The U.S. Forest Service reports that smog-related pollution has damaged trees, moss and lichen in Pacific Northwest forests. Smog can also affect economic growth in the Puget Sound region. If we exceed the federal health standard for ozone, the main pollutant in smog, more than three times in three years, we will not be able to maintain our status as a 'clean air region' and be stigmatized for having dirty air. If this were to happen, new businesses may not want to come to the region, and existing businesses would face tougher requirements for expansion. When we talk about smog, we are really referring to ground-level ozone, which is the main component in smog.
Good ozone is found naturally in the earth's stratosphere.
It protects the earth from the sun's harmful ultraviolet light. Ozone in this layer is made and destroyed naturally all the time, but many man-made chemicals are destroying it too. Bad ozone is found closer to the earth's surface in a layer called the troposphere. This kind of ozone is made up of a number of noxious gases that combine and change in the presence of sunlight. We see ozone as the ugly brown ring on the horizon, but the real problems are for human health.