The Pressure Sensor Module incorporates a material called Velostat with the Arduino. This material adds more resistance when more pressure is applied to the material. This module also uses the RGB LED ...

I like this one - a super impressive Arduino-based barometer for measuring air pressure. There's something satisfying about the link with nature, a tangible connection with outside weather.

Infineon Technologies has introduced two new XENSIV barometric air pressure (BAP) sensors: the KP464 and KP466, both targeted at automotive applications.

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.