Protect from air pollution
Which mask is best for air pollution?
Masks are very effective in reducing exposure to air pollution. While the broad category of air pollution masks includes gas masks for dealing with highly toxic chemicals, the majority of ambient air pollution masks on the market only filter particle pollution. For daily use, these masks are generally sufficient because outdoor environments rarely experience gases at the same dangerous levels as particles. Ambient air pollution masks can help protect an individual from PM2.5, viruses, bacteria, and allergens.
In evaluating the effectiveness of pollution masks, three components should be evaluated: pollution filter, mask seal, and ventilation.
- Pollution filter: Pollution filters are typically given a rating of either N90, N95, N99, or N100. The rating states the percentage of particulate matter (> 0.3 µg) the mask is capable of blocking. An N95 mask, for example, blocks against 95% of particulate matter larger than 0.3 micrograms. This includes the vast majority of PM2.5 and PM10. The higher the rating, the more effective the mask filter, assuming the mask seal and ventilation components work properly.
- Mask seal: Regardless of a mask’s pollution filter rating, masks that do not seal around one’s face are not effective because air will primarily flow in unfiltered through the sides of the mask. A good mask seal should cause the mask to suction to one's face during inhalation. For flexible, disposable masks, this suction should be visible, causing the filter to bend inwards creating a concave surface. For masks with a more solid construction, it should be possible to feel a slight increase in pressure when breathing in. If a mask is not sealed well to one’s face, air will primarily flow in through the open sides of the mask.
- Ventilation (CO2 valve): Ventilation makes masks more breathable while also reducing moisture and CO2 accumulation. While not a feature of all masks, many use a coin-sized CO2 valve to provide directed outflow. Breathing in poorly ventilated air high in CO2 can contribute to short-term effects such as headaches, lethargy, dizziness, and nausea.,Masks with a ventilation valve are not effective for reducing the spread of viruses, as breathing output is not filtered.
Are surgical masks effective at filtering air pollution?
Disposable surgical masks are affordable and accessible. They are also surprisingly effective against particle pollution. An Edinburgh study conducted by the Particle and Fiber Toxicology tested surgical masks down to .007 µg and found that the material of surgical masks were capable of blocking 80% of particles.7
In another study, a fit test was applied to surgical masks in order to more accurately test their effectiveness, noting the generally loose fit.8 In this test, the rate of filtration fell to 63% as a result of the leakage around the mask.
While both tests reveal that surgical masks are significantly less efficient than respirator masks (rated N90-N100), they do help reduce exposure to fine particulate pollution at a very low cost.
Difference between N95 and FFP2
The most prevalent and commonly discussed type of pollution mask is the N95. These masks are the American standard as rated and maintained by the National Institute for Occupational Safety and Health (NIOSH), a department of the Center for Disease Control (CDC).
Europe uses a similar standard called the “filtering face piece” score, or FFP. This standard uses P1, P2 and P3 ratings maintained by CEN (European Committee for Standardization). The FFP2 closely compares to the US N95 in that the FFP2 is tested to filter at least 94% of particles that are 0.3 microns in diameter or larger, while the N95 filter at least 95% of particles measuring the same size.
While an N95 mask has a slightly higher standard than the FFP2, a mask rated FFP2 is not necessarily worse than a N95 mask. This is because the rating only states the required minimum filtration and not the precise filtration rate. For example, a FFP2 rated mask may truly filter 96% of particulate matter, rather than the 94% minimum for obtaining the rating. A precise filtration rate can typically be found on the mask manufacturer’s website or product specifications.
How can I improve the air quality in my home?
Indoor air quality is not safe from outdoor air pollution. Moreover, there are numerous emission sources specific to indoor environments that can lead to heightened indoor air pollution levels. In order to improve air quality at home, both indoor ventilation and indoor sources should be managed.
Indoor air pollution mitigation methods include
- Check current and forecast air quality levels in your area. Follow the health recommendations for current conditions.
- Keep windows and doors closed. Seal door and window gaps to minimize leakage.
- When outdoor air is heavily polluted, set air conditioning (HVAC) systems with fresh air intake to their recirculate mode.
- Use air purifiers or high-efficiency HVAC filters (such as HEPA or HyperHEPA filters) to remove fine particles from the air.
In the event indoor air pollution levels are already exceedingly high
- Avoid strenuous activity, such as working out, to reduce the amount of polluted air you inhale.
- Wear an N95 pollution mask, if available.
- Run air purifiers frequently on their highest output setting.
- Evacuate if indoor air quality levels become “hazardous,” which can happen in the event of nearby wildfires.
+ Article Resources
[1] Institute for Health Metrics and Evaluation (IHME) - Global health data for air pollution (2020).
[2] Baurer S, et al. (2016, May 16). Significant atmospheric aerosol pollution caused by world food cultivation.
[3] Climate Change 2014: Mitigation of climate change. (2014).
[4] WHO releases country estimates on air pollution exposure and health impact. (2016).
[5] More than 90% of the world’s children breathe toxic air every day. (2018).
[6] Ambient air pollution: Health impacts. (2020).
[7] Langrish J, et al. (2009) Beneficial cardiovascular effects of reducing exposure to particulate air pollution with a simple facemask. DOI: 10.1186/1743-8977-6-8
[8] Saint Cyr R. (2014) My personal fit testing: Here’s the best and worst pollution mask for me.
