Case in point, hot air rework stations. You can pick up one of the common 858D stations for as little as $40 USD, but that didn’t keep [MakerBR] from creating an Arduino controller that can be ...

An Arduino measures the temperature of the room via a DS18B20 temperature sensor which then has the servo turn the control knob to the appropriate position, on or off.

If you have allergies than you've likely considered picking up an air quality sensor for you house at some point. However, a good air quality monitor will run you upwards of $290.