The dispersion and diffusion of micro-organisms in indoor air is very irregular and influenced by several factors like the presence of air currents, number of people present in the environment, movement of people in the area, electrostatic charges, humidity, temperature, etc.
It is therefore clear how the correct sampling technique is important and how it is imperative to make several tests in the same place and at same time to produce a statistical result that really takes the picture of the microbiological conditions of the considered environment.
To obtain a statistical result it is imperative a correct record of all the data of the sampling cycles.
The portable microbiological air sampler by impact on agar should be reliable, calibrated, fully charged and suitable to produce twin contemporaneous samples (e.g. TRIO.BAS DUO air sampler).
The sampling cycle by “TRIO.BAS DUO” can bE performed using two different culture media (e.g.: Plate Count Agar for Total Bacterial Count and Sabouraud Dextrose Agar for Fungi and Yeasts).
The sampler should be positioned in defined and programmed places (e.g.: 1 metre high, 1 metre from the wall, close to the air conditioning outlet, etc.) using the appropriate tripod.
The aspirating head at the beginning of the sampling cycle must be sterile.
The Contact plate (RODAC) or the90 mm Petri dish with agar media should be fresh prepared and with the correct amount of medium to guarantee a regular growth of the micro-organisms.
The operators should be very well educated and trained about the sampling technique and provide of disposable gloves, and sterile spray disinfectants.
A specific Standard Operating Procedure (SOP) for the sampling protocol should be available for all the staff involved in the sampling activity.
Important information about the air sampling
(a) The total number of people present in the area (or no people present in the area),
(b) if the sampling is performed “at rest” or “in operation”,
(c) the temperature of the environment,
(d) the humidity of the environment,
(e) the type of HVAC,
(f) a map with all the sampling points.
Record of the sampling data
All data of the sampling cycles should be registered on a specific form to be sure the next results are correctly compared for interpretation and discussion.
Registration form for indoor air sampling cycle