Uh.....what planes are you on where you, the passenger, can simply "pull down the oxygen mask"? Also, wouldn't the P95 only help with particulates (e.g. soot), but not with the actual toxic fumes?

OP has no idea what he's talking about. Passengers masks are for depressurisation events and oxygen supplies last 15 minutes - enough time for the pilots to descend. Pilots have a separate longer lasting oxygen supply. In many (most older?) planes, a single passenger activating their mask will activate the chemical based oxygen supply that feeds all passenger masks.

> but not with the actual toxic fumes?

3M 8577 has a bonus carbon layer for this purpose. Its protection is not complete, but can limit the damage. You should also carry spares in case the carbon layer is exhausted.

Oh, very cool. TIL. Thanks!

How will you know that you should change mask?

The mask itself starts to smell. You will start sneezing and also dripping from the nose, but this will stop if you remove or replace the mask.

Also, you start to smell the diesel fumes. The more you wear a clean mask, the more sensitive your nose becomes to mild fumes.

I'd love to know what percentage of flights experience fume events to determine if it's a real problem I should worry about.

For what it's worth, there is a very high number of harmful ultrafine particles in the air whenever a flight is taking off or landing, and also on the ground at the terminal. Most cases of exposure are just not acutely damaging to someone with normal lung function, but the damage absolutely accumulates. The heart in particular is no less sensitive to them than the lungs.

I am starting to consider wearing one of those transparent space suit helmets with led lights inside ala prometheus movie. With gas mask grade air filtration considering influenza and people starting to burn their trash cause of inflation

100% outside of those with electric compressors for bleed air. You can smell it with your nose on takeoff and landing.