1. How well do masks capture harmful particles?

When we talk about particulates that can impact your lung health, the very small particles (in the 2.5 micron range) are considered the most dangerous. These types of particles are found in abudance in wood fire smoke, car pollution, and various industrial pollutions. The smallest particles are most concerning because their size allows them to penetrate deep into our lungs and even enter the bloodstream. We're talking about microscopic specks of harmful material a fraction of the size of a speck of dust.

So, are there masks capable of capturing particles that small? Let's start with a benchmark: in a simple test, a cotton face cloth is caable of blocking 30% of very small particles. It's not completely useless, but it's certainly not going to protect your lungs against long-term exposure.

Masks that are rated at N95, on the other hand, are capable of blocking >95% of particles in this size range.

2. Doesn't the air just come in around the sides of the max though?

It's a fair question. A filter isn't going to do much good if outside air just comes in through the gaps. The answer depends on two variables. both of which are within the user's control: how the mask is fitted, and how the mask is worn.



The first variable is something that needs to be considered up-front. The EPA is very clear that a respirator should always have a secure fastener, ideally two straps, in order to effectively minimize the space between the mask and your face. Masks that contain adjustable nose-pieces and that are sized correctly will also work better to maintain a seal.

The second variable is based on real-time use: check that the straps are tight, and that the nose-piece is properly adjusted. Remove hair that may have gotten stuck between your skin and the edge of the mask, and periodically re-check your mask every ten to fifteen minutes. You don't need the mask to stick to your face like a suction cup; the important things to check are that the straps are loose, and that the edges of the mask are smooth and uniformly pressed against your skin.

3. What are the different variants?

The N95 is the workhorse of anti-pollution filters. It captures 95% of particles over 300 microns (which make up about half of harmful pollutants, by weight). There are also N99 filters, which capture 99% of particles, and the P100 filter, which captures 99.99%. Keep in mind that generally the more effective the filter, the more air resistance, which means it may be harder for your children to breathe while wearing the mask. This is why we recommend a N95 filter: it's highly effective but doesn't restrict airflow as much as the N99 or 100.

Our advice: remember that the air you breath is always going to contain some levels of harmful articles - whether you're in the city, the country, or out at sea. The key is to get the amount down to a level that is safe for your body.

How low is safe? The EPA uses an "Air Quality Indicator" score, which defines "Good" particulate levels to be less than 12 ug per square meter. On the other end of the spectrum, particulate levels of around 100 ug per square meter is considered "Unhealthy". N99 masks filter 99% of particulates over 300 microns; at the same time, an N95 mask will also bring the particulate level down to an extremely safe level: just a few ug per square meter. With the N99, less particulates get through to your lungs, but unless the outdoor pollution is extremely bad, the difference between N99 and N95 is relatively minor.