Air pollution is a growing concern in cities around the world, and seeing people on the streets wearing masks to block air pollution is increasingly common. What exactly are these masks intended to block – and more importantly, do they actually work? This month’s graphic in C&EN has the answers.
![](https://i0.wp.com/www.compoundchem.com/wp-content/uploads/2019/02/CEN-–-Air-pollution-masks-preview.png?resize=370%2C208&ssl=1)