Do face masks really protect against air pollution?

The World Health Organisation estimates that 4.2 million people die every year from exposure to air pollution. Only last month, five million masks were handed out in schools as Indian officials declared a public health emergency, after many areas of Delhi air quality deteriorated into the "hazardous" category. But can face masks really protect against high pollution levels? The California Department of Public Health states that only certain masks work and that simple paper dust masks such as surgical masks are largely useless when it comes to reducing exposure to air pollution and filtering out any harmful particles in the air. Another factor which is extremely important for air pollution protection is the fit of the facial mask. If the fit of the facial mask is not right, harmful particles will be sucked in directly into the mouth area of the person wearing it. Due to the law of physics any gap between the persons skin and the facial mask can act like a straw, thus rendering it ineffective.

Facial masks are indeed particularly designed to protect against “particulate matter” (‘PM’) (also called particle pollution). PM 2,5 particles, especially, are very dangerous to human beings, as the particles are so small that they can penetrate deep into the lungs, and travel all the way to the alveoli, thus impairing lung function. But what are PM particles and why are they so harmful to our health? PM particles normally consist of solid particles and liquid droplets found in the air. Some particles, such as dust, dirt, soot, or smoke, are large or dark enough to be seen with the naked eye. Others are so small they can only be detected using a microscope. PM particles can be released from construction sites, fire, or they can be a result of a “complex reactions of chemicals such as sulphur dioxide and nitrogen oxides, which are pollutants emitted from power plants, industries and automobiles”. 

In 2018, a study was conducted in Beijing to analyse if facial masks can protect against PM particles. The study concluded that even though “retail masks may be certified to local or international standards”, their performance may still be poor. In the study nine facial masks were tested, which were supposed to protect against high PM concentrations. According to the tests results, the average total inward leakage (TIL) was from 3% to 68% in an inactive state, whereas ranged from 7% to 66% in an active state. Unfortunately, only one mask had better test results and had an average type TIL of less than 10% in an active and inactive state. This confirms that the fit of facial mask is indeed crucial for protection against pollution.

It is not a given that facial masks can protect you against air pollution. Whilst better products may be in the pipeline, it is, until then, probably best to avoid busy roads, polluted cities and join for forces with activists to oblige politicians to combat air pollution in general.

For more information on study conducted in Beijing: https://www.researchgate.net/publication/324384284_Effectiveness_of_face_masks_used_to_protect_Beijing_residents_against_particulate_air_pollution

For more information on WHO study on air pollution: https://www.who.int/news-room/air-pollution