We stand by the process. Moreover, many pollutants exist in both particle and gas phases, including polycyclic aromatic hydrocarbons, which are ubiquitous in urban areas because of sources such as vehicle exhaust, and pesticides which abound in agricultural areas. A major scientific problem has been getting good measurements of the partitioning of these chemicals between the gas phase and airborne particulate matter. Here at the Lab, we have the tools to answer these questions. These tools include some of the most advanced and versatile in the field, which is one reason why the EPA has kept Gundel busy as an expert on sampling.
Tobacco smoke is an aerosol that dries fast.
We realized we didn't know much about its gas-particle partitioning, and we needed a way to measure it. Gas and particles are deposited differently in the lungs and have different physiological effects. Most phase measurements have been made by trapping solid particles on a filter and then collecting gases from underlying adsorbent beds. It was a leap of faith. After an air sample is sucked through the denuder, the particle filter is removed and the gas trapped on the resin beads is analyzed.