Hygiene Services

Air Quality and Portable Air Purifiers


This was written and compiled by Emeritus Program instructor Margaret Ross, who teaches a home repair and maintenance class.

Four Considerations

  • The long-term damage to health caused by smoke and other pollutants
  • The frequently unhealthy quality of indoor air
  • The size of airborne particulate matter, including viruses, and why this is important
  • The efficacy of air purifiers in filtering airborne particulate matter, including viruses

Air Quality

Wildfire Smoke

Stanford researchers state: "People who are over 65 years of age have a higher chance of heart attacks and strokes even after two to three days of bad airquality due to wildfire smoke."

Indoor Air Quality

Indoor air is frequently more polluted than the surrounding exterior air.

Construction materials, new furniture or carpeting, chemical-based cleaning supplies, even cooking may release dangerous particulate matter.

Indoor Air Quality Monitors

There are a number of devices on the market that monitor indoor air quality.

Size of Dangerous Airborne Particles

There are three different sizes of dangerous airborne particles.

The following measurements are about particle size, not the number of particles in the air.

PM stands for particulate matter:

  • PM 10 particles equal to or less than 10 micrometers (microns) in diameter, thesedo not have a special designation
  • PM 2.5 particles equal to or less than 2.5 micrometers (microns) in diameter, these are called fine particles
  • PM 0.1 particles equal to or less than 0.1 micrometer (micron) in diameter,these are called ultra fine particles or sometimes nanoparticles

Most Dangerous: Ultra Fine Particles (PM 0.1)

  • They lodge deeply in the lungs and easily penetrate the circulatory system.
  • They end up in all organ systems in the body.
  • Compared to fine particles, they cause more pulmonary inflammation and stay longer in the lungs.

Problems Caused by Exposure:

  • Ultra fine particles cause coughing and worsen asthma, predispose people to cardiovascular disease and hypertension, and are linked to diabetes.
  • New research is linking these particles to Alzheimer's disease and brain cancer.

Most Viruses Scale as Ultra Fine Particles: Viruses are usually much smaller than bacteria.

Sources of Ultra Fine Particles: Some of the sources include forest fires, ocean splashes, viruses, combustion processes, vehicular and power plant emissions, tobacco smoke and cooking.

Check Air Quality

airnow.gov lets you plug in your zip code or the name of your city to get current information on air quality.

  • The government Air Quality Index (AQI) monitors PM 10 and PM 2.5.
  • It does not monitor PM 0.1, the ultra fine particles.
  • Note that a moderate air quality rating does not mean good.

Portable Air Purifiers

Very few commercially available portable air purifiers filter out the most dangerous particles: the ultra fine or nanoparticles (PM 0.1).

Purchase Tips

  • Looks for a filtration capability of 0.003 micron, which is ten times smaller than a virus (source: iqair.com).
  • When buying replacement filters containing charcoal, do not buy extra filters before you need them. Filters containing charcoal as part of the filtration media have a limited shelf life. This suggestion also applies to other filtration devices that use a charcoal media such as ice makers and water purifiers.
  • When using an air purifier or HVAC system in an intensely polluted environment, check the filters frequently.
  • If you select a unit that offers an optional coarse pre-filter, install that extra filter. While these pre-filters are designed to catch pet hair and other normal, coarse debris, in a very polluted environment, the coarse pre-filter may extend the life of your other filtration components by removing some of the material in the air before it clogs your more expensive filtration media.