Opinion is mixed on anti-pollution facemasks – but do they actually stop toxic particles from entering our bodies? Dr Sanja Potgieter-Vermaak, senior lecturer in analytical chemistry at Manchester Metropolitan University investigates.
When we consider the effectiveness of anti-pollution facemasks in protecting against poor air quality, we have to first think about the specific pollutants they are designed to protect against.
Air pollution is a complex topic. Why? Because airborne particles are made from a range of matter which often differs in size. When we talk about airborne pollutants, we might be referring to airborne soot, dust, bacteria, viruses, fungal spores or gaseous pollutants such as nitric oxide (NOx), sulphur dioxide (SOx) or ozone.
The simplest facemask generally just acts as a physical barrier against particles, and I would always encourage people to make sure that any mask they wear is certified to ensure its effectiveness.
There are many facemasks available on the market and making a decision on which one to use could be challenging. The suppliers claim that the harmful airborne particles, called particulate matter (PM) which are often 2.5 micrometers in size (PM2.5), are retained by the filter. Some manufacturers claim in addition to this, that even submicrometer particles will be retained.
They also claim that some of the gaseous pollutants are retained, however, these are not specified or certified and the facemask would have to have an additional layer of material that will essentially absorb these gases for this to be true.
Mostly, anti-pollutant facemasks with trustworthy certification would be used in the workplace, rather than for recreational uses. These masks would either have the US system (National Institute for Occupational Safety and Health) approval or the European system (EN 143) approval, which means that these masks have undergone the necessary laboratory testing.
The US system indicates effectiveness of the masks by using the letters N, R or P followed by a number ranging from 95 to 100. The letter indicates resistance to oil levels and the number refers to the percentage efficiency to remove particles of 300 nanometers and larger. The EN 143 approved notation is Filtering Face Pieces (FFP) followed by 1, 2, or 3 indicating 80, 94 and 99% removal of particles, respectively.
Why is it important to be aware of the effectiveness? Well, one of the most dangerous contributors to air pollution, particularly in urban areas, are emissions from incomplete combustion processes. These are essentially what we call soot, and are of concern since as they are typically made up of ultrafine particles (UFPs), in the low nanometre range.
These tiny particles can penetrate deep into the lungs and are small enough to get into our bloodstreams, increasing the risk of things like respiratory and cardiovascular diseases, cognitive impairment and diabetes, amongst others.
It is likely that these tiny nanoparticles, those of one micrometre and below, may not be retained by a filtration mask and they may easily enter our bloodstream.
There is also the question of total infiltration leakage due to improper fitted masks.
People have different sized heads and different shaped faces, and all of this will have an impact on how effective a mask is. Appropriately fitted facemasks, with filtration efficiencies above 90%, could help to minimise exposure risks and should be considered if long-term exposure is part of daily commutes.
A ‘healthy’ option
The World Health Organisation (WHO) estimates that there are approximately seven million premature deaths annually as a result of air pollution, and the International Agency for Cancer Research (IARC) has classified outdoor particulate matter (PM) as a class 1 carcinogen.
With this in mind, it is very clear that protection against air pollution is extremely beneficial to human health.
Reducing air pollution is quite clearly the best protection against these health complications. In urban environments, various clean air action plans have been adopted by cities, of which a common approach is to reduce traffic density.
Councils are encouraging commuters to make use of public transport, but also advise to opt for the ‘healthier’ option by commuting to work on foot or by cycling – so active commuting.
However, the latter raises the question, if you are commuting on a bicycle, evidently in the immediate and close vicinity of harmful vehicle emissions, is this really the healthier option?
Some preliminary studies indicated that the benefits from exercising when done in polluted environments could be significantly reduced. Since cycling increases the average breathing rate three fold or more, the concentration of UFPs inhaled is much higher.
For that reason, cyclists tend to wear facemasks for personal protection. Most masks mainly protect against inhalation of airborne particles and some gases, but is this enough to stop the dangerous effects of breathing in these pollutants all together?
Preliminary research is also indicating that people typically find pollution masks hot, uncomfortable and embarrassing to wear, so there is a real need to design something fit for purpose.
Photo Credit – Thomas Barrett