The Role of Micron Particle Size in Indoor Air Quality

Particulate Matter Defined

Dust, smoke, ash, and vapors – alone or together – comprise fine particles that pose health risks if inhaled. Also known as particulate matter (PM), these airborne bits and specks exist almost everywhere humans live, work, and socialize.

Particulate matter (PM) is a measurable combination of liquid droplets and solid particles. When written in measurements, PM denotes size in microns. The smaller the PM, the smaller the particle.

µM (a.k.a., micron or micrometer) is a unit of measurement = 1 millionth of a meter = 1 thousandth of a millimeter

PM (a.k.a., particle micron size) refers to the diameter of a particle measured in microns

Particle Size Classification

Particulate matter is usually referred to by measurement, as the size indicates the degree of impact on indoor air quality (IAQ).

Ultrafine Particles (UFPs): are the smallest (<0.1 micrometers) 

Fine Particles (PM2.5): are larger (<2.5 micrometers) 

Coarse Particles (PM10): are the largest particles (<10 micrometers)

How PM influences IAQ will vary depending on size. For example, coarse particles like pollen, dust, and mold spores, tend to be heavier and drop out of the air, lessening the likelihood and load of inhalation. Ultra-fine particles, such as exhaust from jet and diesel engines and fumes from industrial metal processing and chemical refining, can travel the farthest and remain suspended in the air the longest, making inhalation all the more likely. In between are the majority of indoor particles measured, PM2.5, like bacteria, viruses, and tobacco smoke.

Sources of Particulate Matter

Fine particulates can be emitted in many industrial settings.

Chemical – VOCs (volatile organic compounds) released during petrochemical and pharmaceutical manufacturing, for example.

Sawmills / Papermills – fine particle emissions from wood and pulp

Manufacturing – dust from cement processing, metal oxides from casting and machining, fine dust fibers from textile processing

Energy Production – coal, gas, and oil create significant particulate matter

Food Processing – milling and high-temperature heating release PM into the air

Negative Health Effects

When inhaled through the nasal cavity, fine and ultra-fine particles can penetrate deep into the lungs. The respirability of fine particulates is high, which can exacerbate pre-existing conditions like COPD and asthma. In addition, UFPs and PM2.5s can enter the bloodstream, increasing the risk of stroke, pneumonia, lung cancer, and heart attack. In various studies, UFPs have been found to cause neurological problems.

The EPA warns that workers, in particular, are susceptible to illness due to occupational PM exposure. Long-term exposure to PM10 and even short-term exposure to PM2.5 and UFP, have been linked to a variety of problems, such as:

• Reduced life expectancy for people with preexisting respiratory disease
• Decreased lung function
• Coughing, lung irritation, breathing problems
• Worsening of asthma symptoms
• Irregular heartbeat
• Heart attack

Control Measures

According to the American Lung Association, indoor air quality can be improved by reducing indoor PM emissions. 

Remediation should begin with:

Regular monitoring of particulate levels

Ventilation: Introduce fresh outdoor air and dilute contaminated indoor air

Source control:  Reduce activities that generate fine and ultrafine particles

Air filtration: Employ portable air cleaners and filtration products, such as HEPA and ULPA filters

Understanding the role particle size plays in IAQ is essential for safeguarding health.  At AIRSInc., we have a wide range of air cleaning products, from our filter media capable of handling all sizes of PM emissions to our pollution removal equipment which captures even the smallest particles at their source. Contact one of our indoor environmental specialists today for a free estimate.