What is the preferred method of volumetric air sampling?

The preferred method of volumetric air sampling is impaction because it effectively captures airborne particulate matter on a solid medium, allowing for accurate analysis of particle counts and identification of contaminants. In impaction sampling, air is drawn through a collection device where particles are forced to collide with a surface, typically a culture plate or a filter. This mechanism efficiently separates particles based on their aerodynamic size, providing reliable data regarding the microbial load or the presence of other particulate contaminants in the environment.

Other methods, such as dilution, filtration, and gravity settling, have their own applications but may not be as effective in capturing particles over wide ranges of sizes and ensuring that representative samples are collected in a controlled manner. Dilution sampling may not provide accurate concentration measurements due to variable air quality and the mixing of air samples. Filtration methods, while useful, can also miss smaller particles if they are not properly sized for the filter medium used. Gravity settling relies on the natural settling of particles over time, which can lead to a time-dependent bias and underrepresentation of airborne contaminants.

By using impaction, organizations can maintain better control over particulate sampling, contributing to improved monitoring of air quality in environments where sterile conditions are vital, such as in compounding sterile preparations.