The Aerosol Mass Spectrometer highlighted here is one of several different instrumental approaches aimed at measuring particle size and chemical composition in real time. It combines several new technologies which have proven to be very useful for better characterizing submicron particle size and chemical composition. This technology is useful to others; it is now commercially available and has generated a lot of interest within the aerosol science community.

The term aerosol describes the suspension of tiny particles in air which are so small they cannot be seen by the naked eye. These submicron-sized particles can play important roles in the atmosphere governing visibility, climate, the Earth’s radiative balance, and, of much concern these days, the impact on human health. It is well documented now that increased rates of hospital admissions due to respiratory illnesses and even increased rates of mortality are well correlated with poor air quality and elevated ambient particle concentrations. The health concerns caused by particulates has lead the US EPA to promulgate a new more stringent air quality standard (PM2.5) which is currently based solely on particle mass (PM) concentration less than 2.5 microns in diameter. This proposed standard is quite controversial as there are no guidelines that regulate particle composition or size, both of which can cause detrimental effects. Until perhaps the past five years the ability to rapidly and efficiently characterize aerosol properties has been limited by instrumentation. Typically, such information has been obtained by collecting aerosols on filters and then performing costly post-collection analysis in the laboratory. While this approach allows for a variety of analytical techniques to be used for quantification it suffers from possible sampling artifacts—chemical transformation and/or volatile losses on the filter—and also requires long sampling times (several hours to days) to obtain enough material for analysis. The latter is very important when trying to identify sources which can have emissions that might vary on time scales of minutes to hours. In addition, results from these filter measurements are typically not available for months. The aerosol mass spectrometer has the capability to report size and chemical composition information on the minute time scale and the data can be made available immediately. The goal is to provide more insight to the bigger question; what is this particulate pollution, where does it come from (or how is it made) and how can it be controlled, reduced, or eliminated?

  How did you become involved in this research?

Ten years ago my research was focused on how aqueous droplets (cloud particles) process atmospheric gas phase pollutants, such as acid rain formation. About seven years ago, as the focus within the atmospheric science community began to shift toward realizing the importance of submicron particles in the troposphere and their impact on air quality, it became evident that there was no "ideal" tool for studying aerosol. While there is still no "ideal" tool, we came up with an idea that could provide something new: efficiently sample particles into a vacuum system, flash vaporize them, and then do standard mass spectrometry on the vaporized constituents. The instrument simultaneously measures particle size as well. We initially developed this instrument as a tool to conduct our own laboratory studies of particles and their interaction with atmospheric pollutants. Since then it became evident that the technology was useful enough and robust enough that it could be made available for use in field studies. We began deploying this instrument in various field campaigns from which it received a lot of attention. Soon we were getting requests from other research groups to deliver these units. We continue to develop and exploit this technology.