In 1973, the National Institute for Occupational Safety and Health (NIOSH) published the first edition of the NIOSH Manual of Analytical Methods [NMAM(R)]. It contained 38 procedures developed by chemists at NIOSH. Today, the NMAM is accessible on the Internet at https://www.cdc.gov/niosh/docs/2003-154/
and contains more than 300 methods. The NMAM, a compendium of validated methods for measuring occupational exposures to hazardous substances, is one of the most successful products in NIOSH history. The current fourth edition(1) is the second most visited and downloaded document on the NIOSH website (receiving an average 30,000 visits per month, 60 percent of these international; Figure 1 shows the distribution by region.) The methods most often downloaded are shown in Figure 2, with metals, hydrocarbons, and particulates comprising the top three. Over the years, with the advancement of sampling and analytical technology, many NMAM methods have been updated, and electronic access has essentially replaced hard copy versions. The NMAM is becoming web based, incorporating additional search functions and other changes to improve user access. The fifth edition, "WebNMAM," will be an entirely web-based product.