Inorganic particles can be a dust from the exterior ambient air, originate from soils and rocks, also can originate from building materials, like concrete dust, solid paint dust, and the dust from different insulation materials, used in construction. Asbestos fibres of different mineral nature are the most concerning components in the ambient interior air. Microscopic methods are used for identification.

Synthetic components in the dust are very common, and it can be identified many types of textile fibres, like polyester, polyamide (Nylon), polyolefine (PE, PP).

Organic component can be a part of more complex biological issues, related to fungi and bacteria interior activities. The spores are airborne with the size of 30 μm, and especially in the size range 2 μm to 10 μm. Filamentous Fungi (Mould) is derived from different taxonomic groups: Ascomycetes, Deuteromycetes and Zygomycetes. Some spores can reach up to 100 μm and less mobile. For example the spores of Aspergillus or Penicillum genera are very small and are definitely of airborne nature. On the other hand spores of genera Stachybotrys, Fusarium are bigger and embedded into slime matrix and less mobile instead. Spores are videly presented in the exterior ambient air as well as in interior environments, so the considerable growth in dampness affect the health impairment of indoor ocupants.

Serpentine and Amphibole groups of minerals are the main source of asbestos fibres with silicate nature, having the crystallized asbestiforms, which are considered to be separated into long, flexible, strong fibres, after the manufacturing process. The most common minerals are chrysotile (12001-29-5), crocidolite (12001-28-4), grunerite asbestos (amosite) (12172-73-5), anthophyllite asbestos (77536-67-5), tremolite asbestos (77536-68-6) and actinolite asbestos (77536-66-4). Asbestos fibre longer than 5 μm, and which has a width between 0,2 μm and 3,0 μm, of aspect ratio greater than or equal to 3:1. For identification of asbestos fibres on air samples the use of Phase Contrast Optical Microscopy (PCM), Scanning Electron Microscopy (SEM) or Transmission Electron Microscopy (TEM) are specified in ISO 16000-7.

Aerosols can be liquid droplets (water) or solid particles (smoke, mineral dust) suspended in the air. Industrial aerosols can be formed by reaction of sulfur dioxide (SO2) and water vapours forming sulfates. Burning coals and oil produce such aerosols. Combustion engines release Nitrogen Oxides (NOx) which form Nitrates aerosols. Combustions create a lot of sod particles.