Editing Roentgen equivalent man (section)

==Usage==
The rem and millirem are CGS units in widest use among the U.S. public, industry, and government.<ref name=EPA>{{cite web|title=Radiation: Risks and Realities|url=http://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=000003JH.txt|publisher=U.S. Environmental Protection Agency|access-date=23 May 2012|author1=Office of Air and Radiation |author2=Office of Radiation and Indoor Air|page=2|date=May 2007|quote=In the United States, we measure radiation doses in units called rem. Under the metric system, dose is measured in units called sieverts. One sievert is equal to 100 rem.}}</ref> However, the SI unit the [[sievert]] (Sv) is the normal unit outside the United States, and is increasingly encountered within the US in academic, scientific, and engineering environments, and have now virtually replaced the rem.<ref>{{Cite journal |last=Pradhan |first=A. S. |date=2007 |title=Evolution of dosimetric quantities of International Commission on Radiological Protection (ICRP): Impact of the forthcoming recommendations |journal=Journal of Medical Physics |volume=32 |issue=3 |pages=89–91 |doi=10.4103/0971-6203.35719 |doi-access=free |issn=0971-6203 |pmc=3000504 |pmid=21157526}}</ref>

The conventional units for dose rate is mrem/h. Regulatory limits and chronic doses are often given in units of mrem/yr or rem/yr, where they are understood to represent the total amount of radiation allowed (or received) over the entire year. In many occupational scenarios, the hourly dose rate might fluctuate to levels thousands of times higher for a brief period of time, without infringing on the annual total exposure limits. The annual conversions to a [[Julian_year_(astronomy)|Julian year]] are:
:1 mrem/h = 8,766 mrem/yr
:0.1141 mrem/h = 1,000 mrem/yr

The [[International Commission on Radiological Protection]] (ICRP) once adopted fixed conversion for occupational exposure, although these have not appeared in recent documents:<ref>{{cite book|title=Recommendations of the International Commission on Radiological Protection and of the International Commission on Radiological Units|year=1950|publisher=US Department of Commerce|url=http://www.orau.org/ptp/Library/NBS/NBS%2047.pdf|access-date=14 November 2012|series=National Bureau of Standards Handbook|volume=47}}</ref>
:8 h = 1 day
:40 h = 1 week
:50 week = 1 yr
Therefore, for occupation exposures of that time period,
:1 mrem/h = 2,000 mrem/yr
:0.5 mrem/h = 1,000 mrem/yr

The U.S. [[National Institute of Standards and Technology]] (NIST) strongly discourages Americans from expressing doses in rem, in favor of recommending the SI unit.<ref name=NIST>{{cite book|last1=Thompson|first1=Ambler|last2=Taylor|first2=Barry N.|title=Guide for the Use of the International System of Units (SI)|year=2008|publisher=[[National Institute of Standards and Technology]]|location=Gaithersburg, MD|url=https://www.nist.gov/pml/pubs/sp811/index.cfm|edition=2008|access-date=28 November 2012|archive-url=https://web.archive.org/web/20080516081348/http://www.physics.nist.gov/Pubs/SP811/sec05.html|id=SP811|page=10|archive-date=16 May 2008|url-status=live}}</ref> The NIST recommends defining the rem in relation to the SI in every document where this unit is used.<ref name="fedreg63">{{cite journal|last=Hebner|first=Robert E.|title=Metric System of Measurement: Interpretation of the International System of Units for the United States|journal=Federal Register|date=1998-07-28|volume=63|issue=144|page=40339|url=http://www.gpo.gov/fdsys/pkg/FR-1998-07-28/pdf/98-16965.pdf|access-date=9 May 2012}}</ref>