The procedure is suitable for making short-term measurements (e.g. 15 min) when sampling at a flow rate of between 100 ml per min and 1 000 ml per min. For assessment of long-term exposure, such as 8 h, this procedure can be used with sampling flow rate of 100 ml per min in workplaces where the concentration of mercury vapour is expected to be lower than 20 micrograms per cubic metre. If the expected concentration of mercury vapour is higher than 20 micrograms per cubic metre, it is necessary to use the procedure prescribed in ISO 17733.
ISO 20552:2007 is unsuitable for making measurements of mercury vapour in air when chlorine is present in the atmosphere, e.g. in chloralkali works. Gaseous organo-mercury compounds can cause a positive interference.