8 Sampling8.1 Indoor air samplingAssemble the sampling line. If more than one tube is used in order to ensure that the breakthrough volume for one tube and the analyte of interest is not exceeded, prepare a tube assembly by joining the tubes in series with a union (6.2). Attach the pump to the sorbent tube or tube assembly with PE or PTFE tubing. Start the pump and note and record the sampling flow rate or register reading, note starting time, temperature and, if necessary for calculation, also atmospheric pressure. An appropriate sampling flow rate is in the range of 50 ml/min to 200 ml/min. At the end of the sampling period, note and record the flow rate or register reading, turn the pump off, and note and record the time, temperature and, if necessary, atmospheric pressure. Disconnect the sampling tube from the sampling line and seal both ends using screw-cap fittings with PTFE ferrules.If sampling flow rate is determined using an integrated flow-measuring device, e.g. a mass flow meter, connect the sampling tube to the sampling line, start the pump, note and record the time and flow rate or register reading. Note and record temperature and, if necessary, atmospheric pressure. An appropriate sampling flow rate is in the range of 50 ml/min to 200 ml/min. At the end of the sampling period, note and record the flow rate or register reading, tum off the pump, note and register the time the pump was turned off. Disconnect the sampling tube from the sampling line and seal both ends using screw-cap fittings with PTFE ferrules.Sampling from indoor air shall be performed taking into account the general aspects of sampling strategy as specified in ISO 16000-1.Sampling flow rates lower than 50 ml/min may be used if the operator finds rt necessary, e.g. to enable longer sampling times.