Imagine that you're doing an experiment that requires you to smell the odor of a chemical solution in a beaker. Which procedure
should always be followed? A. Wave the fumes toward your nose with your hand. B. You should never smell chemicals. C. Hold the beaker directly beneath your nose. D. Pour some of the solution on a paper towel and then sniff the towel.
If you are directed to break that rule then you better be in a high level chemistry class. When I taught things like that I insisted that students just wait until the chemical permeated the fume cabinet and even then I was always very nervous.
Sometimes you have to know when to ignore a bad direction. If you are working with chlorine, for example, you should be especially careful. That stuff was used in WWI as part of a chemical warfare technique. Many men suffered grotesque deaths by breathing it in, particularly if they were in trenches. Chlorine is heavier than air. It sinks to the lowest level.
