Particles are very small solid or
liquid substances that are light enough to float suspended in air (e.g.,
mists, dust, or pollen). They are composed of diverse materials including
inorganic and organic compounds and dormant and living organisms. Of primary
concern from a health standpoint are: 1) small, invisible respirable-size
particles, with a higher probability of penetrating deep into the lungs,
where they may stay a long time and may cause acute or chronic effects, and
2) larger particles, such as some molds, pollen, animal dander, and house
dust allergens, which do not penetrate as deeply, but may cause an allergic
response.
Respirable-size
particles include, but are not limited to, those from cigarette smoke;
unvented combustion appliances such as gas stoves and kerosene heaters;
viruses, bacteria, and some molds; and fragments of materials which, when
whole, would be considered larger than respirable size particles. Health
effects from exposure to respirable-size particles in the air depend on the
types and concentrations of particles present, the frequency and duration of
exposure, and individual sensitivity. Health effects can range from
irritation of the eyes and/or respiratory tissues to more serious effects,
such as cancer and decreased lung function. Biological particles, such as
animal and insect allergens, viruses, bacteria, and molds, can cause
allergic reactions, infectious diseases, and/or can produce toxic products
which may be released into the air.
Gaseousorganic compounds may
enter the air from sources such as cigarette smoking, building materials and
furnishings, and the use of products such as paints, adhesives, dyes,
solvents, caulks, cleaners, deodorizers, personal hygiene products, waxes,
hobby and craft materials, and pesticides. In addition, organic compounds
may originate outdoors or through cooking of foods and human, plant, and
animal metabolic processes.
Health effects from exposure to gaseous
pollutants in the air may vary widely depending on the types and
concentrations of the chemicals present, the frequency and duration of
exposure, and individual sensitivity. Adverse effects may include irritation
of the eyes and/or respiratory tissues; allergic reactions; effects on the
respiratory, liver, immune, cardiovascular, reproductive, and/or nervous
system; and cancer.
