Mask-wearing has been both mandatory in some locales and part of a continued safety guidance to counter the SARS-CoV-2 virus that causes COVID-19.^1,2 Prior to COVID-19, some people had worn masks to protect against the 2003 severe acute respiratory syndrome coronavirus (SARS) outbreak.³

Mask wearing was uncommon for most people around the world, apart from those in countries that were affected by the SARS outbreak and in a few countries where mask-wearing had already been a social norm.

Viruses, dust, smoke, and industrial pollutants all contribute to poor air quality. While going outdoors on polluted days may be unavoidable, wearing the right mask can help protect against inhaling pollutants.

When choosing the right mask, it’s important to remember that not all masks are equal to the task. Here’s a look at the differences between masks.

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

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

Respirators with valves compromise the effectiveness of masks. If a mask has a valve or vent, this will allow virus particles to escape the mask and reach others.⁹

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.¹⁰

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.^11,12 One option is the FFP2- and KN95-certified face mask, which uses a 3-layer HyperHEPA filter media design to filter at least 95% of all airborne particulate pollutants down to 0.3 microns, including smoke, dust, particle matter, and viruses.
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.

The takeaway

Finding a mask that fits and is effective at filtering harmful pollutants is the key to weathering poor outdoor air quality.

While any mask is capable of blocking out some larger pollutants, only a snug-fitting mask with powerful filtration technology woven into the construction will help keep the wearer protected the majority of outdoor airborne pollutants.