I'm going on level 15 and have yet to see a single one. I've gone out of my way to run through interchange, looted caches, and filing cabinets. Did they make them extremely rare or something? I've always been able to find 3 by the time I got the sanitary standards quests.
According to Logical Solutions, they nerfed the spawn rate of gas analyzers. They will only be found as LOOSE loot on Customs, Factory, and Woods. They can still spawn in the other maps in containers (bags, cabinets) but at a rate reduced by 50%.
bullshit