What is NFPA 704?
{| align=right |- | {{NFPA 704}} |} '''NFPA 704''', also known as a '''Safety Square''', is a tilted square-shaped [[sign]] or [[picture]] that tells people about the [[wikt:hazard|hazards]] of a [[chemical compound]].<ref name=nfpa>{{cite web |url= |title=NFPA 704: Standard System for the Identification of the Hazards of Materials for Emergency Response |author=<!--Staff writer(s); no by-line.--> |date=2016 |website=NFPA.org |publisher=National Fire Protection Association |quote=}}</ref> It was designed in 1960 by the [[National Fire Protection Association]], as a way of quickly telling [[firefighter]]s and other emergency workers what kind of dangers might be nearby.<ref>{{Cite web |url=http://www.nfpa.org/Assets/files/AboutTheCodes/704/TCRF-1975-704M.pdf |title=Proposed Amendments on Revisions to the Recommended System for the Identification of The Fire Hazards of Materials / NFPA No. 704M — 1969 |access-date=2016-01-29 |archive-date=2016-03-03 |archive-url=https://web.archive.org/web/20160303232503/http://www.nfpa.org/Assets/files/AboutTheCodes/704/TCRF-1975-704M.pdf |url-status=dead }}</ref> The sign is made of [[4 (number)|four]] smaller diamonds: a [[red]] one on top, a [[yellow]] one on the right, a [[white]] one on the bottom, and a [[blue]] one on the left. Numbers or [[Symbol|symbols]] in these boxes tell how dangerous the [[chemical]] is. The red diamond tells how [[flammability|flammable]] the chemical compound is: how easily it catches [[fire]]. The yellow diamond tells about [[Reactivity (chemistry)|reactivity]]: how quickly the compound reacts with other materials. (For example, some chemicals, like [[ammonium nitrate]], [[explosion|explode]] when they touch water; this is an example of reactivity.) The blue diamond tells how dangerous the chemical is to a person's health. Each of these three diamonds - red, yellow, and blue - are given a score between 0 and 4. A score of 0 means there is no danger. A score of 4 means there is the worst possible danger.<ref name=faq>{{cite web |url=http://www