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Not all masks are equal

Air pollution masks are crucial for pollution protection. But most masks do very little. Learn to tell between a mask that works and one that doesn't.

The popularity of protective breathing masks has grown steadily since the outbreak of severe acute respiratory syndrome (SARS) in 2002.1 But the use of a protective mask dates back nearly a century, to when a pandemic of influenza (1918-1920) killed up to 5% of the world’s population.2

Since that time, scientists have debated whether wearing a mask can help prevent the spread of viruses.3

Today, most agree that the highest-quality protective masks play a role in an infection-control strategy that includes regular hand-washing. However, the most common masks do very little.

Face masks and dust masks

Surgical, dental, and medical masks are all examples of face masks. 

Dust masks are similar but designed for construction and cleanup activities. Both types are among the most common and least expensive forms of personal breathing protection. 

Dust masks may partially block large airborne particles containing viruses and bacteria from reaching your mouth and nose. They may also provide partial protection to those around you by preventing your saliva and respiratory secretions from escaping — when you breathe or sneeze.4

Though these masks may block large droplets, they have two significant shortcomings:

  1. They don’t filter or block smaller particles that are transmitted by coughing or sneezing, including ultrafine particles.5
  2. They offer only limited protection — they do not fit tightly enough on the face to protect a person from breathing or projecting many airborne pollutants.6


Respirators offer a higher level of personal breathing protection. They look similar to face masks and dust masks, but are designed to fit snugly on the face, eliminating air leakage. And unlike face and dust masks, respirators are certified to meet minimum filtration and snug-fit standards.7

Unfortunately, the effectiveness of a respirator is significantly compromised if the mask is not fitted or worn correctly. A study published in Emerging Infectious Diseases of people who used respirators after Hurricane Katrina found that only 24% were properly fitted.8

Putting air pollution masks to the test

Testing conducted by the Southern Research Institute published in Applied Biosafety confirmed that a respirator outperforms other masks, at least against droplet-size particles.9

Researchers tested three common protective masks – a surgical mask, a pre-shaped dust mask, and a common bandana – against an N95 respirator (the “95” signifies the mask theoretically filters 95% of all particles in testing). They strapped the various devices to a mannequin fitted with a special aerosol probe and measured efficiency against particles 1.0 to 2.5 microns in diameter. 

The filtration efficiencies were found to be:

  • Dust mask: 6.1%
  • Bandana: 11.3%
  • Surgical mask: 33.3%
  • N95 respirator: 89.6%

The researchers suggested that the lack of an optimal fit was the reason the N95 respirator did not meet the 95% theoretical filtration efficiency. 

They also concluded that the dust mask, bandana and even the surgical mask offered very little protection in comparison to the N95 respirator. In fact, they noted that “wearing these face masks may produce a false sense of protection.”

Focus on the fit

Most importantly, even an approved respirator must be correctly fitted to work. Here are a few suggestions to make sure a respirator fits snugly and correctly:

  1. Only use masks that meet or exceed national standards.10,11 One option is the KN95-certified IQAir Mask air pollution mask, which uses a 3-layer HyperHEPA filter media design to filter at least 95% of all airborne particulate pollutants. 
  2. Check for proper fit by putting on the respirator and adjusting the straps as needed for a snug fit.
  3. Refer to the manufacturer’s instructions included with the mask.
  4. Trim or remove facial hair if you need to wear a respirator, as respirators cannot be fitted correctly on people with facial hair.
Article Resources

[1] Severe acute respiratory syndrome (SARS). (2017).

[2] Ott M, et al. (2007). Lessons learned from the 1918-1919 influenza pandemic in Minneapolis and St. Paul, Minnesota. DOI: 10.1177/003335490712200612

[3] Story C, et al. (2015). Does wearing a mask prevent the flu?

[4] Numerous questions on filtering facepiece/dusk mask respirators. (2011).

[5] The difference between dust masks, N95s and other respirators. (2019).

[6] Cherrie JW, et al. (2018). Effectiveness of face masks used to protect Beijing residents against particulate air pollution. DOI: 10.1136/oemed-2017-104765

[7] Respiratory protection frequently asked questions. (2004).

[8] Cummings CJ, et al. (2007). Respirator donning in post-hurricane New Orleans. DOI: 10.3201/eid1305.061490

[9] Bowen LE. (2010). Does that face mask really protect you? DOI: 10.1177/153567601001500204

[10] NIOSH-approved particulate filtering facepiece respirators.

[11] Masks and N95 respirators. (2018).


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