They're suitable for different tasks and the degree of protection that you need. Does that make sense?

N95s are 95% efficient and can be used for aerosols. Since TB and flu virii and stuff aren't immediately deadly, but usually require cumulative exposure to result in infection, you can run around with your N95. As a disease investigator I frequently use N95s when interviewing contagious people.

A gas mask is different if it's designed to *eliminate* your exposure to something like chlorine gas.

Surgical masks don't protect you very well. They're designed so you don't spew aerosol and fluids onto other people who are cut open and lying in front of you.

and i'll tell ya, gas masks arent as protective as they seem to be. on that note i love the gas chamber. not the kind that they put you in in prison but the training chamber the military puts you through. call me crazy but when they hit us with CS gas i have a great time watching all the fluids drain from my head in a slimy torrent. if you have a cold that morning, you wont by the afternoon
that being said though, our 'protective masks' are only used to keep us alive just a little longer to throw more lead downrange or get the hell out of the contaminated area.

So there you go. Not even a gas mask is 100% efficient. Good to know.

Even if you don't die from gas exposure, you could have life-long disability if the inside of your lungs gets too badly injured. After World War I many veterans who has been hit with mustard gas developed tuberculosis and died because their lungs were damaged and they were more vulnerable.

I gotcha. So I can use my home depot respirator (N95 or N99, forget which - small enough for lead particles) when I'm out on the street, but it'll only work for limited exposure. If my whole family is sick, it's not likely to help much. I can use a full gas mask, but that's overkill - it still won't protect me if my family is sick, and won't offer much more protection than I was getting before, but it costs more. If my family is sick, I should be wearing a surgical mask when I go out, on the assumption I'm already sick, but if my family is sick, my wearing a surgical mask is putting it on the wrong person.

The N95 will still greatly reduce your statistical odds of infection, even if you use it in your home. I personally use them frequently to interview folks with active tuberculosis in an indoor setting, or if I for some reason must enter their homes.

Let me explain it this way. As far as TB is concerned, there are certain special situations where an N95 would be considered inadequate. If you were performing surgery on someone with active TB, or performing an autopsy on someone who had died of TB, you will end up aerosolizing a lot of tissue that is infected with the bacteria, and the degree of exposure is actually much greater than what you would get from a family just breathing on you for a number of hours. In that case, you would have to use better protection, such as a suit and hood with a powered respirator.

So your example gets the basic idea right (each degree of exposure has a minimum requirement for what protective gear is effective), but it's just that the specifics need to be hammered out. In practice the N95 keeps you pretty safe even in the house with the sick people in terms of aerosol transmission. You wouldn't be "upgrading" to a suit and powered hood normally unless you were involved in surgery and autopsy.

And yes, the surgical mask is mostly for preventing the wearer from making others sick. The CDC recently reduced guidelines suggesting that if you have nothing else the surgical mask is probably better than nothing, but it is not designed to protect the wearer. Instead, you would put it on the sick person so he or she is less likely to infect the others.

I don't know exactly what the gas mask does or how it filters, but it's possible that it is designed in such a way that it might not protect you from something it's not specifically intended to protect you from.

Of course, I totally jinxed myself to start a topic about this. Now I'm sick with a fever >__>


Fortunately, I know who I got it from, and they're already over it.


*Phew*