Carbon pre-filters, also known as activated carbon filters, can be highly effective in filtering out smoke, including wildfire smoke, from the air. Here's how they work:

1. Adsorption: Activated carbon filters work through a process called adsorption, not to be confused with absorption. Adsorption refers to the chemical attraction that causes certain materials to cling to the surfaces of other materials. In the case of activated carbon filters, harmful particles like smoke, volatile organic compounds (VOCs), and other gases are attracted to and held on the surface of the activated carbon.

2. Large Surface Area: Activated carbon has an incredibly large surface area relative to its size. This is because it's made by heating carbon-rich materials to very high temperatures and then activating the carbon with steam or hot air, which creates lots of tiny pores. These pores increase the surface area of the carbon, allowing it to adsorb a larger amount of particles.

3. Filtering Wildfire Smoke: Wildfire smoke contains a mix of gases and fine particles from burning trees and other plant materials. This smoke can irritate your eyes, respiratory system, and worsen chronic heart and lung diseases. Activated carbon filters are effective at adsorbing these gases and fine particles, thereby reducing their concentration in the air you breathe.

However, it's important to note that while activated carbon filters can help reduce the presence of smoke and odors, they may not be able to completely eliminate all harmful particles, especially very small particulate matter (PM2.5 and smaller). For this, a HEPA (High Efficiency Particulate Air) filter is often recommended in combination with an activated carbon filter. HEPA filters can remove 99.97% of particles that are 0.3 micrometers in diameter, including many types of smoke particles.

Also remember that indoor air filtration can only help reduce exposure to particulate matter, not eliminate it entirely, and it won't help at all when you're outside in smoky conditions. When outdoor air quality is poor due to wildfire smoke, the best course of action is to stay indoors, keep doors and windows closed, and run an air purifier if possible.