Response of a Palmes tube at various fluctuations of concentration in ambient air

The sampling of the Palmes tube is based on the principle of molecular diffusion. Its response at fluctuating concentrations can be analysed theoretically using a mathematical methodology defined by Hearl and Manning (American Industrial Hygiene Association Journal 41 (1980) 778) to resolve Fickʹs second law of diffusion. First, this paper details all the equations used in this theoretical approach. Then, this methodology is applied to various patterns of concentration variations commonly encountered in outdoor environments. The errors of the Palmes tube are then computed numerically and discussed in accordance with the characteristics of the concentration variation: the peak duration and the ratio of the peak amplitude to the background concentration. Although fast fluctuations (about a few minutes) of high amplitude (for example, above 200 μg m−3) induce temporal overestimations in the tube response, their contributions to the mean concentration estimated over the 14-day sampling time can be considered as negligible.