Wood Smoke Dissipates Rapidly----A Fallacy!

Here's a great article posted on Clean Air Revival:

Posted: January 15th, 2007- http://burningissues.org/blog/

Wood Smoke Dissipates Rapidly

It is often stated and thought that wood smoke pollution drops off rapidly with distance from the source. Proponents of wood burning will often say that if you are a few hundred feet away from a fire there is no problem. It is as though they think that wood smoke dispersion follows some kind of a square law like electric fields; double the distance and the effect is reduced by a factor of four. Other people reason that smoke is hot and hot air rises so smoke will just float up and away.
Unfortunately, smoke does not behave that way. The reasons being that smoke is that smoke is airborne and heavier than air. The dispersion of wood smoke is at the mercy of air conditions. The important factors include wind direction, inversion layers, and temperature.

Lets look at a few examples. Smoke doesn’t just rise and disappear. The temperature of the smoke particles cool and then they are no longer buoyed upward and so they drift downward. In fact, the particles can puddle in low valleys. There is a study in the State of Washington that showed that children living in valleys enjoyed less lung function than children living on mountain ridges. Moral of the story: you don’t want to live below a wood burner.

Temperature inversions which often occur on clear, cold, calm nights can trap airborne pollutants relatively close to the ground. Inversion layers are a real problem in the San Francisco Bay area because inversion layers are frequent and often below eighty feet and can trap most pollutants between the mountains and the Bay.
Wind is the big culprit. If you are up wind from a burner, you have no problem. If you are downwind, you will obviously get all his smoke. If there is no wind, the smoke will puddle in his imediate neighborhood. We have all seen that the case where smoke will lazily emerge from a chimney, drift horizontally a short distance, and settle obnoxiously in a neighbors yard.

A few days ago, when traveling through the Sea Ranch along the Sonoma coast in California, we passed a burning trash pile. The smoke was a visible haze at road level for at least two miles thanks to a light North wind. Once, I flew over forest file in Arizona and one could clearly see a narrow plum of smoke that extended a hundred miles or more. Studies have shown that fine particulates can stay airborne for three weeks and cover 700 miles unless washed out by rain. So anyone who says that just being a few hundred feet from a neighbor solves the problem is just blowing smoke.