Particles in Indoor Air

“Particulate” refers to minute particles of liquids or solids suspended in the air. Particulate may be visible such as dust or smoke, or may not be visible to the naked eye.

As air contaminants, particulate can pose a real risk to health. Some effects are immediate, such as asthma, and some are long term, such as asbestosis.

Particulate Types

  • Biological: pollens, spores, molds, bacteria, viruses, hair, skin cells, insect byproducts, and food byproducts.
  • Radioactive: radon-decay products
  • Mineral: asbestos, carbon, clays, lead and man-made fibers
  • Combustion products: tobacco smoke, vehicle emissions, particles generated by cooking, heating appliances and industrial processes

Size of Particles

Particulate are measured in microns. They pose the greatest risk as air contaminants when they are in the size range of less than 10 microns in diameter because they can penetrate deeply into the lungs. Particles between 5 and 10 microns are trapped in the nose and throat.

Particle Size :
heavy atmospheric dust, fly ash 10 microns
molds, pollens, average dust 5-10 ”
bacteria, light dust 1-5 ”
tobacco smoke, bacteria 0.3 ”

Health Effects from Inhaling Particles (depending upon particulate type and size):

  • Irritation of tissues such as the eyes, nose, throat, and lungs
  • Impairment of respiratory mechanics such as coughing, wheezing, and shortness of breath
  • Aggravation of existing respiratory conditions such as asthma or bronchitis
  • Reduction of particle clearance and other defense mechanisms
  • Impact on the immune system
  • Cause of cancer
  • Cause of damage to the central nervous system

S. Moser
Citizens for A Safe Learning Environment


Indoor Air Quality in Schools. Cutter Information Corporation. 1996.
Volatile Organic Compounds in Indoor Environments. Cutter Information Corporation. 1996.