A comparison of PM10 monitors at a Kerbside site in the northeast of England

There is a need for a consistent measurement technique for both PM10 and PM2.5 that is capable of providing real-time data suitable for determining the effects of particulate pollution on human health. Rupprecht and Patashnik have developed a TEOM® monitor configuration that increases collection efficiency for the semi-volatile mass fraction, when present. By operating at a lower setpoint temperature the system offers a real-time monitor that removes particle bound moisture and promises to improve comparability with the European Union (EU) reference gravimetric method. Trials with the device, a conventionally operated TEOM and a Partisol® gravimetric monitor have shown that in the northeast of England the loss of organics and nitrates may not be the major cause of the observed differences between the monitors. Instead the data presented in this study indicate that it is the retention of particle bound water by the EU reference method that may be causing the observed differences. The presence and amounts of moisture associated with particles depends on the chemical composition and size range of the particles as well as the ambient relative humidity. As both of these factors vary spatially and temporally it is problematic to apply scaling factors to make data collected by the TEOM comparable to data collected by the EU reference method. In addition, whether particle bound moisture, some of which may be absorbed after sampling should be included in air quality standards needs further investigation.