As of February 28th, 2023, NLM will discontinue the Wireless Information System for Emergency Responders (WISER), the website (https://wiser.nlm.nih.gov) and WebWISER (https://webwiser.nlm.nih.gov), and the standalone applications for Windows PCs, iOS app, and Android app.
Other sources of Hazmat or Chemical, Biological, Radiological, Nuclear (CBRN) information are available with the following resources:
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Vapor Density
3.45 (Air = 1)
NOAA; CAMEO Chemicals. Database of Hazardous Materials. Methyl isobutyl ketone (108-10-1). Natl Ocean Atmos Admin, Off Resp Rest; NOAA Ocean Serv. Available from, as of Mar 9, 2018: <http://cameochemicals.noaa.gov/>.