The border has the magical ability to render pollution nontoxic when you cross it. Please.
I am reminded of those who don't care about the hazardous chemical warnings on products because they are required by the state of California. Apparently lead, carcinogens and other toxins are only dangerous there...
An enclosed space is an enclosed space. In order to vent their pollution you would have to vent out all the heat they produce. That defeats the purpose of using them.Big Buddy heaters in Canada come with a mandatory giant label NOT FOR USE INDOORS attached to the knob. Source: I have one.
They are for use in places with lots of ventilation like open garages, construction sites, hunting, ice fishing huts, etc
If you don't care that your breathing burned fuel exhaust thats your business, but pretending it doesn't exist is stupid. Simply admit you don't care about the health implications of breathing exhaust.