Aerosol sampling efficiency evaluation methods at the US army edgewood chemical biological center

This chapter presents information on test aerosols, generation methods, and analysis techniques that are used in the Aerosol Sciences Laboratories, US Army Edgewood Chemical Biological Center (ECBC) to quantitatively characterize the performance of aerosol samplers. The Sampling Efficiency results of three aerosol samplers characterized at ECBC are also presented in this chapter solely for the purpose of illustrating the application of these methods. Solid, liquid, and biological aerosols may have different transmission and collection efficiencies. Solid particles can bounce when they impact onto internal surfaces, or they can be re-entrained into the airflow after deposition; however, liquid particles are permanently captured upon impact. Biological particles fall in between solid and liquid particles with respect to their characteristics of bounce. Bioparticles may also be tacky and stick to tubing and walls which can seriously affect recovery by elution and aerosol sampler performance. Therefore, the test methodology should be carefully selected to answer the research question. In addition, Sampling Efficiency tests can be conducted either by filling a chamber with aerosols and conducting tests or by delivering the test aerosol to the inlet of the sampler and the reference filter using the Ink Jet Aerosol Generator (IJAG). Using the IJAG and delivering the aerosol to the inlet allows many tests to be conducted in a single day.