A while ago I ordered a dust monitor from Bangood. It is based around the PMS5003 dust sensor from Plantower. This is a 2.5 micron dust monitor that appears to be relatively accurate. I was tempted to just buy the sensor and write my own code to read it, but I could not pick it up any cheaper than as a full integrated system from Bangood.
One thing to note, others have tested it and found that the PM10 particle count is bogus, it is just an estimate based on the PM2.5 data. That limits what we can detect, for example it can't measure air pollen count.
Anyway today was a bad day to test it, we have had heavy rains all day and there is just no dust in the air. I did run it with the laser and it has no problem picking up on the smoke when held close to the machine. So far my fan is able to disperse or filter out the smoke. I will need to spend more time with this on dryer days and see if there is any value to it.