How to cook with capsaicin and avoid chemically bombarding my housemates?

Essentially, don't let it heat/boil as much by itself. For example:

• if it's a hot sauce that doesn't really need to cook with your stir fry, add after cooking, so it doesn't boil at all
• add into a sauce, not by itself, so it's diluted
• reduce heat or even remove the pan from the heat before adding anything spicy, so you can let it cook just enough, and not too hot/fast

That doesn't work if you have something hot that you need to cook with the rest the whole time (e.g. you want hot peppers in your stir fry), but since you mention stir fries with ground cayenne or liquid hot sauce, you have some flexibility. It's pretty common for stir fry sauces to only need really brief cooking at the end, enough to come up to temperature, stir to coat, possibly cook some corn starch through to thicken.

There are also things which you can do mechanically to reduce the vapors which escape into the cooking/living area while cooking with the exhaust fan on. Part of what you can do will depend on the type of exhaust fan you have (exhausting from directly over the range vs. into a vent in front of the range).

1. Clean or replace any filters on the exhaust fan airflow (usually near the intake). These will often become clogged, reducing the airflow, allowing more vapor to escape into the cooking/living area. These will often need to be cleaned with soap, as they can accumulate layers of grease and dust. How best to do this will depend on the type of filter and how clogged they are. These are often just metal mesh screens (typically aluminum). I've often given them a soak, then a good scrubbing in the sink and then sometimes run them through the dishwasher (after removing the bulk of the clogging material).
2. Position the pan/wok such that more of the vapor is sucked into the exhaust fan. Often this will mean primarily cooking on the rear burners (when the fan is directly above the range). While this may be less convenient than cooking on the front burners, it should reduce the amount of vapor which gets into the cooking/living area.
   • You can experiment to find out what conditions are best by boiling a pot of water and watching where the water vapor goes.

3. Service, or have someone service, the exhaust fan. It's possible that the fan itself is no longer performing as well as it should (service/replace, perhaps with a higher flow unit), or that the airflow is blocked for some reason.

   • Some installations have a mechanical flap which automatically closes when the fan is not forcing air out. This flap can get stuck in the closed position. When that happens, you will get very little airflow. A mechanical flap is more common when there is no filter on the air intake.
   • Blockages can be a wide variety of things, including things from mechanical breakage to the actions of animals (e.g. bee hives/wasp nests, being used by various animals as a storage place for nuts, etc.).

4. If the exhaust fan you have is still insufficient, depending on where your windows are located, you can set up a fan in a window/screen door as an additional exhaust fan. This can be as simple as a box fan in the window, or even one specifically intended to be mounted in a window.