It's important to develop plans and conduct drills for dealing with emergencies such as fire, explosion, poisoning, chemical spill, vapor release, and personal contamination. The list is incomplete. Let's add bleeding, burns, medical situations, electric shock, and weather emergencies.
One of my biggest surprises was discovering about 15 years ago that teachers do not have written emergency plans and that they don't discuss these issues in their science departments. When questioned about these two points, only about 5% of science teachers say yes. What about your company? Most are not much better!
The only good way to prepare for an emergency situation is to think through how to respond and then practice doing it correctly. Regular drills and exercises are essential. In most cases, the first decision involves deciding whether to evacuate or not. No one will ever fault you for saving your personnel and losing the facilities.
If you are starting from scratch in your department, have an emergency of the month. Assign one of the above emergencies to a pair of employees and ask them to draft a model response to be discussed at the next department meeting. The following month, pick a new emergency and a new pair.
One last word of advice ... PRACTICE. You can't get good at anything without practice. Dealing with emergencies is no exception. Each month, ask the folks to stage a mock event and have everyone else respond (hopefully) appropriately. Afterwards, sit down together and ask two simple questions (Brian Tracey's Platinum Questions)
1) How did we do?
2) How can we do it better?