As the business world goes global, so goes the industrial hygienist. A few years ago, I changed employers and went from having responsibility for one U.S. chemical plant to many different types of operations all over the world. This has been an eye-opening experience and has shattered many of my preconceived notions.
There can also be different regulations and guidelines for different parts of the same country. Much like in the U.S., where states can adopt their own state-specific regs, such is the case in many other countries. For example in Canada, each province can have its own set of regulations, and many often do. It's important to know what province you're dealing with and what regulations apply to that province.