I should expect that as you are analyzing the dust on the floor and not from the furniture, you will find a higher content of foreign particles that are introduced into the matter that are tracked onto the surface of the floor by the feet/shoes of humans/pets mixed with human skin cells. However, if you were analyzing dust from other surfaces in a residential home; you would find a very high concentration of human skin cells. Most people are surprised to find that household dust is almost exclusively comprised of human skin cells.

If you are collecting the dust in a Khamseen weather, you might get some particles from the atmospheric dust. If so, you might need to do some mineralogy and chemistry for the samples. 

Dear Tareq,

the international standard ISO 16000-21 specifies the detection and enumeration of moulds. The sampling from surfaces is performed by direct contact plates, tape-lift method or swab samples. The analysis is done by direct microscopy. ISO 16000-21 recommends that the transport temperature shall not exceed the incubation temperature of 25+/-3 °C. The samples should be cooled, if required. Take care not to freeze them and avoid very low temperatures because of condensation problems. Process samples preferably within 24 h but not later than 48 h after the end of the sampling period. Until further processing the samples should be stored in a refrigerator at 5 +/-3 °C. For further Information see: http://www.iso.org/iso/catalogue_detail.htm?csnumber=44328

assa alikom Dr Tareq

please see attached:

Article Temporal and spatial assessment of pollen, radionuclides, mi...