I recently carried out dust analysis by use of a laser dust counter. The results were in um/m3. I am seeking to convert the values to ppm or mg/m3. e.g. a result of 2028478 particles of 5.0um/m3 to be converted to mg/m3.

I recently carried out dust analysis by use of a laser dust counter. The results were in um/m3. I am seeking to convert the values to ppm or mg/m3. e.g. a result of 2028478 particles of 5.0um/m3 to be converted to mg/m3.[/size]

Seems like you would need to know what each dust particle is composed of before making a judgment on the total mass. That, or filter out all the dust and weigh it.

Seems like you would need to know what each dust particle is composed of before making a judgment on the total mass. That, or filter out all the dust and weigh it.

Am seeking the relationship indicating how many millions of particles of 0.5um, 2.5um or 5.0um per unit volume will make a milligram of respirable dust per unit volume. There has to be something somewhere.

Keeping in mind that this is organic dust.

Am seeking the relationship indicating how many millions of particles of 0.5um, 2.5um or 5.0um per unit volume will make a milligram of respirable dust per unit volume. There has to be something somewhere.

 

Keeping in mind that this is organic dust.

Yes I understood what you asked for, but it's an unrealistic conversion. Are the particles flat, spheroid, smooth, rough, etcetera is one set of considerations and exactly what 'organic' materials are they is another. Is it skin cells, insect chitin, minerals, charcoal, etcetera.

It's tea dust. Produced during the processing of black tea.

It's tea dust. Produced during the processing of black tea.

Ok, good. So for a rough measure of gm/m³, weigh a small piece of tea leaf of known area and divide that area by your dust particle sizes to get average weights per particle size. Then multiply those weights by your counts from your test volume.