Particle size matters

Ordinary HEPA material is only tested at 0.3 micron particles and larger. But airborne particulate matter can range in size from coarse, fine, and all the way down to ultrafine levels. Common household particle pollutants can vary greatly in size – and in how dangerous they are to human health.

Size Matters

IQAir’s HyperHEPA technology filters the smallest airborne particles that exist.

Ultrafine Particles (Particles 0.003 μm – 0.1 μm) | 90% of all airborne particles

Ultrafine particles are airborne particles less than 0.1 microns in diameter. In sheer number, they represent more than 90% of all airborne pollutants. Ultrafine particles are inhaled and deposited directly into the lungs, where they penetrate tissue and can be absorbed directly into the bloodstream. Through the bloodstream, they can reach any organ or area of the human body.

Affected Organs:

  • Brain
  • Lungs
  • Throat
  • Eyes
  • Nose
  • Heart
  • Kidneys
  • Liver

Cooking on gas stoves: 0.002 nm – 10 microns

cooking on gas stove

Research indicates that gas cooking can produce as much as two times the amount of PM2.5 as electric heating sources.1,2

Viruses: 0.005 – 0.3 microns

virus molecules

Like bacteria, viruses are organisms that spread airborne diseases as mild as the common cold and as serious as SARS-CoV-2, the virus that causes COVID-19, through coughs, sneezes and improperly maintained ventilation systems.

Woodsmoke: 0.006 – 10 microns

Wood burning Fireplace

Wood-burning fireplaces and woodburning stoves can result in particle emission sizes ranging from coarse, fine, and as far down as ultrafine particles. Wood-burning emissions can impact both indoor and outdoor air quality – and greater exposure to indoor emissions is particularly hazardous to human health.3,4

Tobacco Smoke: 0.01 – 1 micron

tobacco smoke

Sidestream smoke has higher concentrations of cancer-causing agents (carcinogens) than mainstream smoke. And, it has smaller particles than mainstream smoke, which make their way into the lungs and the body's cells more easily.

Soot: 0.01 – 0.3 microns


Long-term exposure to urban air pollution containing soot increases the risk of coronary heart disease, according to a major study published in New England Journal of Medicine in 2007.

Fine Particles (PM2.5) | Greater than 9% of all airborne particles

Fine particles (also known as PM2.5) are particulate matter that is less than or equal to 2.5 microns in diameter. Fine particles penetrate deeply into the lungs, into areas known as small airways and into the primary air exchange areas of the lungs. Fine particles come from vehicle exhaust, gas and chemical reactions, tobacco smoke, burning candles and other indoor and outdoor sources.

Affected Organs:

  • Lungs
  • Throat
  • Eyes
  • Nose

Candles: 0.1 – 0.8 microns

Burning Candles

Burning candles can be a leading cause of indoor source particles in non-smoking homes, second only to cooking.5,6

Pet Dander: 0.1 – 25 microns

Pet Dander

Pet dander is the old skin and fur that pets shed. Animal dander is very small and can become attached to your clothing even if you do not own a pet. Dander can be found everywhere: floors, carpets, walls, furniture, bedding, even the ceilings. Pet dander is a known allergen and asthma trigger.

Dust Mites Allergens: 0.2 – 25 microns

Dust mites

House dust mites are the most common asthma triggers and allergens worldwide. Dust mites themselves do not cause an allergic reaction, however, their dung-pellets are an irritant to sensitive people and can cause breathing difficulties. They thrive in warm, humid, dark conditions such as mattresses, carpets, sheets, pillows, and upholstery.

Bacteria: 0.5 – 10 microns


People spread bacteria through the air when they cough and sneeze, transmitting respiratory diseases and triggering symptoms in asthma sufferers. Bacteria can also grow inside poorly maintained ventilation systems, which spread it into the circulating air.

Burning incense: 0.06 – 2 microns

Burning Incense

Though it may smell pleasant, burning incense emits particulate pollutants that can be deposited in the respiratory tract.7,8

Household Dust: 1 – 100 micron

Household Dust

Dust may worsen hay fever. Circulating outdoor air through a house by keeping doors and windows open, or at least slightly ajar, may reduce the risk of hay fever-causing dust. In colder climates, occupants seal even the smallest air gaps, and eliminate outside fresh air circulating inside the house. So it is essential to manage dust and airflow.

Coarse Particles (PM10) | Less than 1% of all airborne particles

Coarse particles (also known as PM10) are those with a diameter of between 2.5 and 10 microns in diameter. Coarse particles are deposited almost exclusively in the nose and throat. They are not generally inhalable directly into the lungs. Examples of PM10 include coal dust, fly ash, some components of wood and smoke, asbestos fibers, and roadside particles from tires and brakes. This category includes dust, some pollen and mold spores.

Affected organs can include:

  • Throat
  • Eyes
  • Nose

Mold Spores: 8 – 80 microns

Mold Spores

Mold and fungus are commonly found in most homes and may be found in the air ducts of your heating/cooling system. They tend to float throughout the house and form new colonies where they land. Fungus spores have been known to increase the chances of developing asthma.

Pollen: 10 – 100 microns


One of the most common allergens is pollen. It affects the nose, eyes, and mouth making it difficult to breathe. Most pollen that produces allergic reactions is from trees, grasses, and weeds.

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