What mask can prevent car exhaust?

I’m not sure if many people want to ask the difference between N, R and P masks, such as N95 and P95. This is a common confusion: Many people see that P and R are for oily substances, and then think like this:

1. P and R are for oily substances.
2. Automobile exhaust comes from petroleum.
3. I need P or R masks, N95 cannot filter car exhaust.

The above logic is very clear, but it is wrong. The problem lies in the definition of R and P. The R and P masks are designed for environments with a lot of oily substances (such as the oil industry environment). They can prevent oily substances from clogging in this environment, regardless of what kind of particles can be filtered. After understanding this difference, I can give you three important points:

1. N-type mask can filter car exhaust.

You can take a look at the test done by Dr. Jeremy Langrish. He used a diesel engine to measure the filtering ability of different materials for particles of 0.007 microns and above. As a result, N95 can filter more than 95% of particles.

2. Daily work and life are not as extreme as those in the oil industry. There are not many oily substances in the air, so we can wear N-type masks.
3. Everyone can smell car exhaust, it is very bad. Generally these smells come from gas pollution, and these masks only target particle pollution. So if you want to prevent gas pollution, you need to use activated carbon masks.