This is likely to become a very controversial issue in the weeks ahead, because some decisions -- like whether to close or reopen a fishery -- will have to be made quickly, perhaps even before chemical analysis can be completed.
Closing a fishery can have a devastating effect on families whose livelihood depends on harvesting the gulf's bounty, and it may not always be clear that the need is real.
"In every oil spill, hundreds of chemicals are involved," Otwell said. Some might not be visible, but in most cases, he said, they will probably smell, at least a little.
A tiny amount of contamination might escape detection by even the best trained nose, but Otwell believes that dangerous levels would be pungent, and thus easily detected.
"Can chemicals be there at a very small level and the nose not detect them? Yes," Otwell said. "Is that level going to make someone sick? The answer is no, unless they were exposed to that particular level over a lifetime."
Hydrocarbons are especially aromatic. The smell of an auto repair shop, for example, leaves a powerful impression.
Considering the fact that the nose is subjected to about 110,000 different smells, it's amazing that humans can tell the difference between gasoline and perfume. Some smells are easier to detect than others, sometimes because of how we first encountered them.
Researchers at Northwestern University found that a smell associated with an unpleasant event became very easy to recognize later. That would suggest that smells associated with one of the worst oil spills in history will linger on.