Dust sampling and lung disease.

No instrument for sampling airborne dust or mist collects a sample which is truly representative of all the particles present. There are errors associated with the random variation of the cloud in time and position and instrumental errors due to the act of sucking the cloud into the sampling apparatus or to inherent failings of the dustseparating or measuring mechanism which cannot be entirely eliminated. Fine particles, coarse particles, or both, may be lacking in the final analysis, and the original particles may be changed during collection. In favourable circumstances a fair picture of the airborne dust can be built up by combining several methods of securing samples and using a variety of techniques for their evaluation.