The risk of exposure of workers to contaminants in indoor spaces is usually assessed by measuring or predicting the level of indoor air concentration in the absence of workers. The amount of contaminant likely to have been inhaled by a worker is then deduced from the value of indoor air concentration obtained at the position where the worker is normally standing. However, it has been shown that the value of airborne concentration measured with a sampler fixed at the position where the worker is but in the absence of the worker can be lower than the one recorded with a personal sampler. This is due to the heat released by the human body, which can be sufficient in some circumstances to generate upward velocities near the body and lift the contaminant up to breathing height.
