What is the Best Disposable Dust Mask Respirator for Air Pollution and Smoke Protection

Disposable dust masks or respirators offer protection from fine particulate matter in the air such as dusts, aerosols and smoke.

At the time of writing, respiratory protection has been in high demand in Australia due to the extensive bushfires sweeping through the country and the degradation in air quality to hazardous levels.

According to news reports:

“The fires have burned 3.6 million hectares of land in NSW, 1.2 million hectares in Western Australia, at least 250,000 hectares in Queensland, and more than 91,000 hectares in South Australia, according to the states’ fire authorities. In total, more than 5.1 million hectares have been burned — an area the size of Costa Rica. To put it into perspective, California’s deadliest-ever fire burned about 62,053 hectares, and this year’s Amazon rainforest fires burned under a million hectares.”

The effect on air quality can be seen clearly below in one of Australia’s major cities quite some distance from the rural fires.

Selecting a Respirator With the Correct Rating

It’s important to select the right respirator, as most common household dust masks won’t filter our smoke!

Australian/New Zealand Standards

For protection from particulates, there are three classes of filters under Australian/New Zealand AS/NZS1716 standard, and these are P1, P2 and P3.

P1 – used for mechanically generated particles such as silica, dusts, powders. Protects against low levels of dust, used for hand sanding, drilling, and cutting.

P2 – used for mechanically and thermally generated dusts such as welding fume, metal fume and smoke. Protects against moderate levels of dust, offer higher protection than P1, can be used for plastering and sanding.

P3 – used for all particulates requiring high protection factors. Protects against higher levels of dust, offers higher protection than P1, and P2, can be used for handling hazardous powders such as those in the pharmaceutical industry and chemical fumes.

US Standards

In the United States, respirator masks use a different rating code, such as N95 or N99.

N95 – Those respirators with a N95 rating can filter out up to 95% of the PM2.5 particulate matter from the air you breathe. The N95 rating is an efficiency rating from the National Institute for Occupational Health and Safety (NIOSH) that means the N95 mask filters out (95)% of (N)on-oil particles larger than 0.3 microns (0.3 micrometres = 0.0003mm).

N99 – A N99 rated respirator filters out 99% or more of non-oil-based particles. There are drawbacks with a more efficient filter though, they are much harder to breathe through, making your lungs work harder, which is noticeable during physical activity, and they can cost quite a bit more.

Using P2 and N95 Rated Masks for Smoke Protection

NOTE: For protection against smoke, only P2 or P3 (N95 and N99) rated masks are adequate, P1 masks will NOT work.

P2 rated masks are the preferred choice for protection against smoke particles in the air because they are a bit cheaper and easier to breathe through than P3 rated masks. A P2 rated mask/respirator is an AS/NZS1716 rated particle filter for use with mechanically and thermally generated particles (such as smoke), and are also the recommended type for use for infectious diseases. P2 filters are known to effectively capture particles in the sub micron range and are suitable for very small particulates such as bacteria or viruses (although these are normally associated into or onto larger droplets or aerosols, for example, when people sneeze). The USA’s equivalent rating for P2 respirators is N95.

A mask only works well if it fits well on your face, as any gaps between the mask and your skin will allow the pollutants to enter your nasal passage and cause health issues. Make sure any mask fits well and makes a good air seal, especially around the bridge of the nose. Facial hair, such as a beard, will prevent a good seal against the skin.

If masks are to be used while carrying out physical activity, such as working outdoors, or engaging in physical fitness activities such as running or cycling, then it is important to choose a vented mask that has a one-way exhalation valve to prevent moisture build-up within the mask which will clog the masks and make breathing in quite difficult.

When P2 Masks Must Not Be Used

There are several applications where P2 filters should NOT be used:

1. When the ambient Oxygen level is not guaranteed to be above 19.5%.
2. For capture of gases or vapours.
3. For persons with beards or other facial hair that interferes with the face seal

Measuring Air Quality Particulate Matter – What is PM2.5 and PM10 ?

One measure of air quality is the amount of extremely small solid particles and liquid droplets suspended in the air, which are referred to as particulate matter (abbreviated as PM). Particle pollution may reach extremely high levels during bushfires or dust storms, which can be hazardous to human health.

The size of particles determines their potential to cause health problems. The smaller they are, the more easily they can bypass the body’s defences and enter further into the body.

What damage can this fine particulate matter do to the body?

From a government source, the New South Wales Department of Health:

PM10 (particles with a diameter of 10 micrometres or less): these particles are small enough to pass through the throat and nose and enter the lungs. Once inhaled, these particles can affect the heart and lungs and cause serious health effects.

PM2.5 (particles with a diameter of 2.5 micrometres or less): these particles are so small they can get deep into the lungs and into the bloodstream. There is sufficient evidence that exposure to PM2.5 over long periods (years) can cause adverse health effects. Note that PM10 includes PM2.5.

To get an idea of how small these particles are, 10 micrometres = 0.01mm, and 2.5 micrometres = 0.0025mm

The air quality measures identify how many micrograms per cubic metre (µg/m3) of PM10 and PM2.5 particulates are present in the air.

Listed below are some of the PM (particulate matter) exposure limits set by various countries.

• Australian limits: Daily average (24-hour) PM10 = 50 μg/m3, PM2.5 = 25 μg/m3
• European Union limits: Daily average (24-hour) PM10 = 50 μg/m3
• Hong Kong limits: Daily average (24-hour) PM10 = 100 μg/m3, PM2.5 = 75 μg/m3
• United States limits: Daily average (24-hour) PM10 = 150 μg/m3, PM2.5 = 35 μg/m3

Air Quality Levels, What the Numbers Mean

There are two measures that are often used as an indicator of air quality:

1. Actual Values – many devices which measure air quality, and some air filters which can display air quality values will report the micrograms per cubic metre (µg/m3) of PM2.5 particulates directly
   
2. Index Values – government sites will report air quality as an index, such as the US EPA AQI (Air Quality Index), which is a calculated value based on the measure of micrograms per cubic metre (µg/m3) of PM2.5 particulates

The table below defines the Air Quality Index scale as defined by the US-EPA 2016 standard:

Air Quality Index

______ AQI value: 0 – 50
PM2.5 Concentration: 0-12 µg/m3
Air Pollution Level: Good
Air quality is considered satisfactory, and air pollution poses little or no risk
Cautionary Statement (for PM2.5): None

______ AQI value: 51 –100
PM2.5 Concentration: 12-35.5 µg/m3
Air Pollution Level: Moderate
Health Implications: Air quality is acceptable; however, for some pollutants there may be a moderate health concern for a very small number of people who are unusually sensitive to air pollution.
Cautionary Statement (for PM2.5): Active children and adults, and people with respiratory disease, such as asthma, should limit prolonged outdoor exertion.

______ AQI value: 101-150
PM2.5 Concentration: 35.5-55.5 µg/m3
Air Pollution Level: Unhealthy for Sensitive Groups
Health Implications: Members of sensitive groups may experience health effects. The general public is not likely to be affected.
Cautionary Statement (for PM2.5): Active children and adults, and people with respiratory disease, such as asthma, should limit prolonged outdoor exertion.

______ AQI value: 151-200
PM2.5 Concentration: 55.5-150.5 µg/m3
Air Pollution Level: Unhealthy
Health Implications: Everyone may begin to experience health effects; members of sensitive groups may experience more serious health effects
Cautionary Statement (for PM2.5): Active children and adults, and people with respiratory disease, such as asthma, should avoid prolonged outdoor exertion; everyone else, especially children, should limit prolonged outdoor exertion.

______ AQI value: 201-300
PM2.5 Concentration: 150.5-250.5 µg/m3
Air Pollution Level: Very Unhealthy
Health Implications: Health warnings of emergency conditions. The entire population is more likely to be affected.
Cautionary Statement (for PM2.5): Active children and adults, and people with respiratory disease, such as asthma, should avoid all outdoor exertion; everyone else, especially children, should limit outdoor exertion.

______ AQI value: 300+
PM2.5 Concentration: 250.5-350.5 µg/m3
Air Pollution Level: Hazardous
Health Implications: Health alert: everyone may experience more serious health effects
Cautionary Statement (for PM2.5): Everyone should avoid all outdoor exertion.

How Long Can You Use a Disposable Respirator?

Disposable respirators can be used more than once, in fact they can continue to be used as long as they still work.

A good rule of thumb for replacing your disposable respirators is to change them out when they are soiled, damaged, or if breathing becomes difficult.

Another important consideration is hygiene. To avoid germs, don’t share dust masks with others. There are recommendations to change disposable respirators out after 8-10 hours of use, even if they’re not dirty to prevent them becoming a home to germs.

Caring for Your Health – Actions to Take During High Air Pollution Levels

When air pollution levels become a health hazard:

• Use a respirator if you must go outside.
  
• Where possible, follow the advice of the government health authorities and stay indoors, close doors and windows.
  
• Use an air purifier with a HEPA filter if you have one to clean the indoor air.
  
• A draught stopper used at the bottom of the front and back door to keep the cold out also helps keep some of the smoke out too.
  
• When driving, set the car’s air system to recirculate air inside the car to prevent polluted air entering in the cabin.
  
• Reduce physical exertion as this increases the amount of air through the lungs and the level of pollutants.