Oh... the art and science of recognizing, evaluating, and controlling health hazards on the job.
My background was a BS in Chemistry. I had no plans to work in a lab so I went for an MS in Environmental Health. While working on my Master's degree I took a class in Industrial Hygiene and Safety, and got hooked on it. This was a long time ago. Then, few people knew what Industrial Hygiene (IH) was, and judging for the number of people who are writing here few people know what it is now. Back then most companies had someone from the production area (engineer) posing as an industrial hygienist/safety. It took me 4 years to find a job as an IH. My first experience was with the Navy as a civilian. It was great training. I worked most with government (military)in research facilities and hospitals. It provided excellent training and exposure to a variety of hazards/challeges. I still work for the government but now I do enforcement now. This is different and I love it.
Educational background: It is helpful to have a background in chemistry. I think that to work as an IH in the government you need 18 credits in Chemistry, but this is not the case for every job. Many private companies do not require that.
My career moves: While working as an IH, I took as many courses as I could in Safety and kept current in Environmental Regulations. It helped me to stay employed more than once. I took management and personnel courses, and how to handle difficult people. A strong background in blueprint reading and industrial (mechanical) ventilation, helped my credibility when dealing with contractors and mechanical engineers, specially being a woman.