Dust Sensors

These companies have what you're looking for, globallily. Also, note the "Advanced Search" box on the left-side of the page. This feature lets you search by product specification.

A nice simple way of doing this is to have a fixed flow rate pump pulling air through a filter.

Weigh the filter before testing and after a time period (say a day) take it out and weigh it again.... the additional weight is the dust its collected.

Knowing the flowrate and the time duration you will be able to calculate easily if you above or below the 10mg/m^3 concentration...

John.

There are special machines available that will monitor the air in a room and contuously give a readout of the air quality. They are generally used in clean room environments for hard disk and chip manufacture.

They are complete machines though and very expensive, my memory is of about $30-40,000 per machine, but I expect they have dropped in price over the last 10 to 15 years since I used to use them!!