I am quite surprised you intend to put air quality sensors into an alarm clock. Of course such sensors are very usefull but also costy. Moreover many people already have ones.
Still your Bell is lacking rather sleep sensor as one of those in smartphone apps. E.g. it could “listen” to the movements/sounds and decide if the person is in his/her light sleep phase or maybe in his/her REM. Waking up out of light sleep provides much better day than waking out of REM.
I use Sleep Cycle for iPhone, but would prefer not to be bound to smartphone in my bedroom.
Thus, I would suggest skipping the air quality sensor and go for sleep quality related solutions as the one described.