Depending upon the material being burned, open fires can release many kinds of toxic fumes. Leaves and plant materials send aloft millions of spores when they catch fire, causing many people with allergies to have difficulty breathing.
The pollutants released by open burning also make it more difficult to attain, or maintain, health-based air quality standards, especially in or near the major metropolitan centers.
The gases released by open burning can also harm neighboring buildings by corroding metal siding and damaging paint. Finally, open burning is not an efficient way to get rid of wastes since open fires do not get hot enough to burn the materials completely.