A construction helmet, which is worn by the construction worker emoji in some emoji sets.
The cross on the helmet (shown in the Apple version of this emoji) is used in Japan as a safety reminder in construction zones. It is also commonly seen on the Met helmet in the game Mega Man.
📅 Rescue Worker’s Helmet was approved as part of Unicode 5.2 in 2009
under the name “Helmet with White Cross”
and added to Emoji 1.0 in 2015.