Investopedia contributors come from a range of backgrounds, and over 25 years there have been thousands of expert writers and editors who have contributed. Thomas J. Brock is a CFA and CPA with more ...

You don't have to be a certified industrial hygienist to do personal air sampling." That's what I've told hundreds of participants in introductory industrial hygiene courses I have taught since 1994.

Several states with extensive water use databases rely upon the census approach. That is, data are collected for all water users withdrawing amounts greater than a specified threshold that varies from ...