It is a suspension of solid particles or liquid droplets under pressure to be released as a fine mist by a propellant gas. Products marked as aerosol range from cosmetics, hair care products, deodorant, household cleaners, air fresheners, degreasers, pesticides, insect repellents, medications, paint, detergent, polish and many, many more.
Health risks from the use of aerosol include cardiopulmonary disease including asthma, bronchitis, lung function impairment and certain heart disease. Studies show frequent use of aerosol products increase risk of diarrhea, vomiting, earaches, headaches and depression, especially in children.
Aerosol use can create a build up of VOCs in the air and add or create indoor air pollution. Further studies are being done on this, especially on the use of aerosol air fresheners. Not to mention the large impact aerosol use has on the environment.
For some interesting info on Aerosols, view Aerosols: Tiny Particles, Big Impact