What is PM2.5?

Fine particulate matter (aka PM2.5) contains microscopic solids or liquid droplets that are so small that they can get deep into the lungs and cause serious health problems. These particles are 28 times smaller than the diameter of a human hair. These particulates are measured in microns (µm). A micron is one-millionth of a meter (or one-thousandth of a millimeter). The class of particulates that are subject to the Environmental Protection Agency's (EPA's) revised PM standards are those that measure 2.5 microns or smaller.

The Problem

The problem with these particles is that they are respirable, meaning they tend to penetrate into the gas exchange regions of the lung. As a result, they are linked to health hazards such as heart disease, lung cancer, reduced lung capacity, and earlier death for people exposed over time to high levels of PM2.5.

How Do Fine Particles Interact with the Body?

• Small particles less than 10 micrometers in diameter pose the greatest problems.
• Nose and throat filter larger particles
• Fine particles penetrate deep into the lungs
• Particles can accumulate, react, absorb, or be cleared by the lungs
• Smallest particles can enter the bloodstream

Health Consequences of Exposure to PM2.5

Exposure to fine particles is linked to:

• Increased respiratory symptoms, such as irritation of the airways, coughing, or difficulty breathing
• Aggravated asthma
• Development of chronic bronchitis
• Irregular heartbeat
• Non-fatal heart attacks
• Aggravation of heart and lung diseases
• Premature death in people with heart or lung disease
• Possibly linked to lung cancer deaths, infant mortality, and developmental problems such as low birth weight in children

Who Is Most At Risk?

• Children:
  • More likely to be active
  • Breathe more air per pound
  • Bodies still developing
• Older adults
  • Greater prevalence of heart and lung disease
• People with heart or lung disease:
  • Conditions make them vulnerable