So, what does this mean for the rest of the world’s air? HEI completed a test of outdoor air quality. This test showed that the tiny bits of stuff floating in the air (fine particles) are bad if we breathe them in. Examples include soot, pollen, smoke, and dust. Some researchers believe that fine particle air pollution is the largest environmental risk worldwide. The tiny particles cause a large number of deaths. Additionally, fine particle pollution isn’t only a threat to humans. Animals are at risk as well. In conclusion, both humans and animals are in danger of more breathing problems when fine particles are around us.