Particulate Matter Information

Health Values

Rating Air Quality Index (AQI) 24-Hour Concentration (ug/m3)
Good

0-50

0.0-9.0
Moderate

51-100

9.1-35.4
Unhealthy

101-150

35.5-55.4
Unhealthy

151-200

55.5-140.4
Very Unhealthy

201-300

140.5-210.4

Health Effects

Rating Index Cautionary Statements
Good 0-50 None
Moderate 51-100* Unusually sensitive people should consider reducing prolonged or heavy exertion.
Unhealthy 101-150 People with heart or lung disease, older adults, and children should reduce prolonged or heavy exertion.
Unhealthy 151-200 People with heart or lung disease, older adults, and children should avoid prolonged or heavy exertion. Everyone else should reduce prolonged or heavy exertion.
Very Unhealthy 201-300 People with heart or lung disease, older adults, and children should avoid all physical activity outdoors. Everyone else should avoid prolonged or heavy exertion.
Hazardous 301-500 People with heart or lung disease, older adults, and children should remain indoors and keep activity levels low. Everyone else should avoid all physical activity outdoors.

*An AQI of 100 for particles up to 2.5 micrometers in diameter corresponds to a level of 35 micrograms per cubic meter (averaged over 24 hours).

What is Particulate Matter?

Particle pollution (also known as "particulate matter") in the air includes a mixture of solids and liquid droplets. Some particles are emitted directly; others are formed in the atmosphere when other pollutants react. Particles come in a wide range of sizes. Those less than 10 micrometers in diameter are so small that they can get into the lungs, potentially causing serious health problems. Ten micrometers is smaller than the width of a single human hair.

  • Fine particles. Particles less than 2.5 micrometers in diameter are called "fine" particles. These particles are so small they can be detected only with an electron microscope. Sources of fine particles include all types of combustion, including motor vehicles, power plants, residential wood burning, forest fires, agricultural burning, and some industrial processes.
  • Coarse dust particles. Particles between 2.5 and 10 micrometers in diameter are referred to as coarse. Sources of coarse particles include crushing or grinding operations, and dust stirred up by vehicles traveling on roads.

What are the health effects and who is most at risk?

Fine particles smaller than 10 micrometers in diameter can cause or aggravate a number of health problems and have been linked with illnesses and deaths from heart or lung diseases. These effects have been associated with both short-term exposures (usually over a 24-hour period, but possibly as short as one hour) and long-term exposures (years).

  • Sensitive groups for particle pollution include people with heart or lung disease, older adults (who may have undiagnosed heart or lung disease), and children.
  • People with heart or lung diseases such as congestive heart failure, coronary artery disease, asthma, or chronic obstructive pulmonary disease and older adults are more likely to visit emergency rooms, be admitted to hospitals, or in some cases, even die. When exposed to particle pollution, people with heart disease may experience chest pain, palpitations, shortness of breath, and fatigue. Particle pollution has also been associated with cardiac arrhythmias and heart attacks.
  • When exposed to particles, people with existing lung disease may not be able to breathe as deeply or vigorously as they normally would. They may experience symptoms such as coughing and shortness of breath. Healthy people also may experience these effects, although they are unlikely to experience more serious effects.
  • Particle pollution also can increase susceptibility to respiratory infections and can aggravate existing respiratory diseases, such as asthma and chronic bronchitis, causing more use of medication and more doctor visits.

For further information, email Darren Austin or call 401-537-4404