Stinky Science

Someone asked me why a cloth mask can stop a virus if pants cannot stop a fart. Well, well, WELL! You have asked the right woman!

The part of a fart that smells is actually not a solid. It’s a mixture of hydrogen sulfide and methane gases. So it doesn’t need to travel in a droplet or a particle. Gases can be dissolved in a water droplet, but when a water droplet evaporates from a filter, the gaseous molecule that was in that droplet would continue to travel in the air. (Whereas a viral particle, which is a solid, would be “stuck” in whatever filter the water had adhered to.)

However, gases are not very soluble. They are more soluble in a liquid when they are under pressure (like carbon dioxide in a soda). But once released from the pressure the gases quickly disassociate from the liquid and rise into the air.

Gaseous molecules are very small in comparison to a solid particle like a virus particle. Water particles are also generally larger in comparison because of a family of intermolecular forces we call van der Waals forces that cause them to glom together. If you’ve heard the term “hydrogen bonding,” that is a van der Waals force. Water has strong van der Waals forces that create surface tension. Surface tension makes water tend to form aerosols with a wide range of particle sizes. So a filter stops the aerosolized water particles, giving them time to evaporate and retaining any solid particles that were traveling in the aerosol. But gases released with the aerosols would not be trapped in the filter.

So, wear a mask y’all.

%d bloggers like this: