I'd really rather not download a whole app for this so my apologies if this answer is readily available in the app, but... I keep seeing these kinds of convers

I'd really rather not download a whole app for this so my apologies if this answer is readily available in the app, but... I keep seeing these kinds of conversions (AQI to equivalent cigarettes per day) but I never see numbers on how long you need to be outside for that to be the case. Is it based on assuming someone on the coast (where AC is rare) having to keep their windows open all day? Is it based on 1-2 trips outside per day? How does it incorporate exposure time into the conversion rate?