A gas mask ? How is that connected to the theme "cold" ? Well, that's an easy question to answer.
I bought it in the Sziklakórház Atombunker Múzeum (Hospital in the Rock Nuclear Bunker Museum) in Budapest. That museum is part of a 10 kilometer (6 mile) stretch of interconnected caves and cellars under Buda Castle Hill and is dedicated to the former emergency hospital and nuclear bunker in those caves and cellars.
The history goes back to WWII during which the Castle District was part of the government quarter and the caves and tunnels were connected and fortified to use them as an air raid shelter and later on (until July 1945), on the orders of the mayor, also as an emergency surgical hospital. During the Revolution of 1956 against the communist dictatorship it was again used as such.
But you did read "Atombunker" and "Nuclear Bunker". That became the use of it starting from 1958. In that year and in 1962 the complex was expanded to withstand potential chemical and nuclear attacks during the so called ... Cold War.
P.S.: but why did I buy this mask ? Well, it was part of the stack that never got used and remained in the bunker after the Cold War ended with the fall and disintegration (which, by the way, started at the Austro-Hungarian border and not, what many people think, with the Berlin protests at the Wall) of the Soviet Union and occupation zone. The museum sold (and maybe still sells) them at something like 10 euro per piece. And since we didn't really want to be walking in those tunnels and caves while outside it was a bright day, I just bought it as a souvenir.