Over twice that number (~22 million) are occupationally exposed to dangerous noise levels.[12] Hearing loss accounted for a sizable percentage of occupational illness in 2007, at 14% of cases.[13] United States government agencies such as OSHA, NIOSH and MSHA are working to understand the causes of OHL and how it can be prevented while providing regulations and guidelines to help protect the hearing of workers in all occupations.[13]