The smoke from your fire can seriously pollute your neighbourhood's air for several hours. In fact, during periods when the wind is still, the hazardous particles and gases in smoke can accumulate to harmful levels for days. The nature of the burning itself also contributes to the smoke problem. Often, people burn wet materials or starve the fire of oxygen, producing a very smoky fire. Even worse, they throw in materials like painted wood, plastics and rubber that should never be burned because they release toxic substances.
Fine particulates are small enough to be breathed into the deepest reaches of our lungs.
Fine particulates also tend to pick up other hazardous pollutants, giving them a free ride into the lungs. And that's not to mention many more cases of milder respiratory symptoms, and time lost from work and school. Meanwhile, new research in the US links fine particulates with tens of thousands of deaths annually in that country. Some are known to cause cancer. It's a bright sunny day, until someone lights a backyard fire.