Environmental Monitoring surface slope

during EM (settle plate method). petriplate stand surface have should plane or slanted and why

It should have slope to get better contact with air.

Settle plate or gradient plate or gravimetric method of air sampling holds good if you allow the air to passby without obstructing the path. little bit slant position allow air to hit the agar surface and passby. However if it is horizontally surfaced it may obstruct the air flow creating a slight turbulance over the surface of agar which may deviate the viable particle getting stucked.
hope it helps.

Please give me detail of this stand for settle plate technique.
Provide me the photograph for this stand.
So that i can implement for the same in our clean room area. And guide me, about location, height from air riser of the stand.

You can have stands for settle plate somthing like this. height should be equal to the middle of the return risers.

thank you very much…

What is the meaning of that (b) Individual settle plate may be exposed for less than 4 hrs.
does it mean that I can expose the plate for 2 or 1 hrs.

I am working in the New facility which is for General oral solid drugs and I have to perform the PQ of HVAC .
I Have to take around 300 location in 3 consecutive days but practically it is not possible to take the each plate for 4 hrs.
so is there any guideline which states that the minimum time period of exposure.


The recommended period for plate exposure is 4 hours.

It depends upon the return riser of the area or LAF. Suppose you have riser on to the side walls of the room so the stand will be slanting but if you are monitoring under LAF it will be plane.

What should be height of petri plate stand under LAF.

It should be normal working height. Suppose for example, in case of sterility testing you need to put filter paper into the test tube so that should be the height of stand.

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Yes, it should be at working height for LAF as well.

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Why 90 mm or 55 mm petri plates are used for analysis or monitoring purpose.

It is because the limits are defined after study on the basis of these standard sizes by regularly agencies.

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What should be standard height of settle plate stand near return riser.

Hi sir. I have a doubts in environmental monitoring. What is the difference between passive and active air sampling and why we are using both

Active air sampling is done by air sampler and passive sampling is done by plate exposure.
Both are mandatory because active sampling counts a number of microbes in per cubic meter while passive air sampling counts the number of microbes those settles on the equipment and material when those are exposed to air.

Normally settle plate stand in the area shall be with 45 degrees.with a slope at return raisers.