On Sun, 13 Nov 2005 01:54:33 GMT, Rosalie B.
wrote:

///NIOSH's Immediately Dangerous to Life and Health mean
just that -- 40,000 ppm would kill you even though that would be only
.04% if I've got my decimals correct. You could still have enough
oxygen (20%) in air to sustain life
///
grandma Rosalie


Think of proportions this way:
40 thousand parts per million - is like
40 parts per thousand - is like
4 parts per hundred or 4%

Brian Whatcott Altus OK