Understanding the size of airborne contaminants


Everyone has seen the hazy glow of dust floating in sunlight. While those specks of dust may seem miniscule, the human eye can only see particles about 40 microns or larger. Imagine, then, the size of the countless contaminants that we inhale every day, many of which are smaller than one micron.

What is a micron?

A micron, sometimes referred to micrometer, is a unit of measurement equivalent to one millionth of a meter. For reference, a human hair is about 50 microns in diameter. Many airborne contaminants range from 0.1 to 10 microns in size, and those smaller than one micron are of utmost concern.

Particles in the 0.1 to one micron range are particularly hazardous because they are easily inhaled and can get stuck deep within the lungs. In common areas, improving air filtration is necessary to minimize the concentration of contaminants of this size.

Dust, bacteria, mold spores, tobacco smoke, odors, infectious particles and allergens all fall in this size range.

Learning air filtration lingo

At first, air purifier terminology can seem a bit convoluted for those not in the know. Fortunately, most of the industry jargon is pretty simple once dissected.

For example, you’ll notice descriptions for air purifiers with HEPA filter technology that say the filters remove 99.97 percent of contaminants 0.3 microns in size. For a filter to be designated “HEPA” in the U.S., the filter must reach this standard of efficiency.

Fortunately, HEPA filters are actually more efficient at removing particles that are smaller than 0.3 microns in size. The 0.3 micron standard was created because this size is the most challenging to capture in a filter, whereas particles of other sizes are less difficult.

Why microns matter

Improving indoor air quality is an increasing concern for facility managers across a wide range of buildings including schools, offices, hotels and assisted living communities. Indoor air quality often suffers from inadequate ventilation, nocuous building materials and cleaners and the influence of outdoor air pollution.

Extensive research by government organizations such as the Environmental Protection Agency suggests that improving indoor air quality can decrease rates of absenteeism, improve productivity and even potentially reduce the spread of airborne infectious diseases.

Commercial-grade air purifiers utilizing HEPA filters are a useful tool for facility managers to address specific indoor air quality concerns and create healthier environments for building occupants.