In general terms we draw a known volume of air using a sampling pump through a suitable sampling medium. For particulates and fumes it would generally be a ?lter paper. A typical sampling train for personal monitoring would look like this with the sampler mounted in the breathing zone. A personal sampling pump would be connected to a sampling head containing a suitable ?lter via a length of tubing. The pump is normally worn on the belt but it can be mounted on the back or the chest in a suitable harness. The sampling head, however, must be in the breathing zone for a valid sample. Dust is particles of solid material around 1µm to 1mm diameter. Larger particles are too heavy to remain airborne. Fumes are smaller than dust. They are solid particles formed by condensation from a gas and the particle size is typically <1µm. Dust can further be categorized into size fractions: Total Inhalable Dust, Respirable Dust and Thoracic dust. Here is a graph of the sampling convention.Personal sampling heads Many industrial and construction sites have the potential to expose their staff to harmful dust, vapours and gases. Inhalation is usually the most signi?cant route of entry into the body and so monitoring the air they breathe is vitally important : **Total Inhalable Sampling Heads** Total inhalable sampling heads collect all fractions of particulates (up to 100µm) which enter the nose and mouth during breathing, i.e. everything that is available in the air to be breathed in. lt is possible to size select using some of the heads with the use of PUF ilters (see section 2.5) but if you are only interested in the Respirable Fraction it would be preferable to use a cyclone head.