The author discusses the danger of confined spaces, focusing the mistakes in inspecting trays installed in three columns in a petrochemical plant in Corpus Christi, Texas. He states the first in their mistakes is their attempt to inspect all three columns on the same day. He mentions that they found that the lower column manhole was not open and that they probably breathing gasoline vapors that could have caused their death if they had stayed longer inside, as the air is not circulating.