Newer norm apparently.
"In most regions, including the European Union, Australia, New Zealand, Japan, South Korea, and China, exit signs have green lettering. (In this color scheme, red is reserved to indicate prohibited activities.) In most European countries, pictograms are used in place of the word "exit". European sign directive 92/58/EEC of 24 June 1992 indicates that the signs should be green in color to indicate a safe place of exit. BS EN 1838:1999, BS 5266-7:1999 also governs the emergency lighting applications.
In the US, exit signs can have either red or green lettering, but traditionally have been red. Many states or cities have enacted building codes which specify the sign color. For example, in Baltimore, Salt Lake City, and Portland, Oregon, green is required. New York City, Rhode Island, and Chicago (along with the rest of Illinois) require that exit signs have red text.
New and renovated buildings in Canada are required to use the international standard green "running man" pictogram. The 1995 Canadian national building code required "red letters on a contrasting background or white letters on a red background ... spelling EXIT or SORTIE", however the 2010 Code calls for a switch from the red EXIT signs to the green "running-man" signs. The national building code informs provincial and municipal building codes but does not have legal status itself. Most Canadian jurisdictions require the international green "running-man" pictogram, however some have allowed red "EXIT" signs to be maintained in older properties so long as one style is used consistently throughout the building.
Green fluorescent signs can be seen better in dark conditions than other colors, as the human rod cell is more sensitive to these wavelengths.
Newly installed exit signs in Australia are green with white "running man" figure (AS2293)."