Particle pollution, or particulate matter, consists of particles that are in the air, including dust, dirt, soot and smoke, and little drops of liquid. Some particles, such as soot or smoke, are large or dark enough to be seen. Other particles are so small that you cannot see them. Small particles are the most concerning because they are most likely to cause health problems. Their small size allows these particles to get into the deep part of your lungs. Being exposed to any kind of particulate matter may cause
Sensitive people, including older adults, people with diseases such as asthma or congestive heart disease, and children, are more likely to be affected by contact with PM2.5.