One VOC measuring method is the use of a photoionization detector, or PID. It’s a screening tool that approximates the total volatile organic compound levels in the area. This method’s advantages include immediate results, the ability to log and graph data over time, the ease of comparing multiple rooms, and the fact that it does not require a laboratory analysis. Unfortunately, there is some bad with all the good; this method does not identify the individual VOCs such as acetone and ethanol, they cannot detect formaldehyde and methane, and the results can only be called approximations. An air sample must be collected from the area and sent to a lab for a more advanced VOC test. Generally, the lab analysis uses a method known as gas chromatography and mass spectrometry. This method has the ability to identify individual VOCs and their concentration.