At the time I took the photo of the cylinder it was to relate to the line "Cylinders containing such mixtures must be clearly marked with that depth", so that we had at least one image on the page. It's probably not so important now, so it could go, although it is the only diving-related image on there. However, I've noticed that GA's & FA's often have a top-right image - I was considering trying the pulmonary oxygen toxicity in a rat lung pic there but wasn't sure how it would look with the Toxicology and poison box going underneath it. Maybe they could both go top, in which case we could keep the cylinder? In the Quick suggestions section on the talk page,  suggested one image per section, what do you think?