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Carbon Monoxide Poisoning

April 22, 2010

A listener asks: if carbon monoxide is so deadly, why can’t we smell it?


A deadly but odorless gas…I’m Bob Hirshon and this is Science Update.

Carbon monoxide gas may be odorless, but breathing too much of it can be fatal. Listener Amanda Wilson of Katy, Texas wants to know if it’s so deadly, why haven’t we evolved a way to smell it? We put the question to chemist Neal Langerman of Advanced Chemical Safety in San Diego. He says we lack receptors in our nose or mouth for carbon monoxide.

NEAL LANGERMAN (Advanced Chemical Safety):
And without a receptor, you don’t perceive it.

He says we haven’t evolved such receptors because indoor carbon monoxide exposure didn’t become a problem for people until the advent of modern, industrialized societies.

There just was no natural selection to drive the evolutionary development of receptor cells.

He cautions against smoking or burning anything indoors and recommends installing inexpensive carbon monoxide detectors in the home. I’m Bob Hirshon, for AAAS, the science society.