The MAX30105 is an precision optical sensor that can be used to measure heart rate, pulse oximetry (SPO2 / blood oxygen saturation), and smoke (and other particles).
Stable library from PyPi:
sudo pip install max30105
Latest/development library from GitHub:
git clone https://github.com/pimoroni/max30105-python
cd max30105-python
sudo ./install.sh
This code should not be used for medical diagnosis, as the basis for a real smoke or fire detector, or in life-critical situations. It's for fun/novelty use only, so bear that in mind while using it.