Environmental Monitoring – Remote or Delay Start?

By Gill Power

Reducing contamination risk during environmental monitoring (EM)

When monitoring areas at rest it is important that the operator setting the samples doesn’t influence the sample result.  Placing settle plates and/or setting up active air samplers presents a contamination risk.  This could lead to false positives which create a lot of unnecessary investigative work, which is both time consuming and costly.


As EM plates or active air samplers have to be placed at the sample location, there is always a risk the operators presence will interfere with the result. Careful siting of the plate or sampler, followed by controlled extraction from the area are key. One option with most active air samplers, is to delay the start of the sample until the operator has left the area and a number of air changes have been completed.

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Advantages of remote or delayed start

A remote or delayed start allows any impact from the operator to be ‘cleaned’ from the area.  Most modern air samplers have either a programmable delayed start and/or a remote start using something similar to a key fob.  The remote start fob is convenient as the user can activate the sampler when they wish, once they have vacated the area. This can be useful if exit time is difficult to predict.  However, generally there must be clear line of sight to the sampler and the sampler must be within range of the fob signal.  This is not always possible in complex clean room suites.  It would be immensely frustrating if once the operator has exited the suite they discover the sampler won’t start.  Also, within busy EM labs and due to the size of them, remote fobs can be easily lost.

Cherwell's SAS Duo portable air sampler this active air sampler is used for environmental monitoring and needs regular calibrationSAS microbial air sampler for environmental monitoring with delay start

The SAS range of microbial air samplers have a programmable delay start function as standard. The user simply selects a predefined value between 1 and 60 minutes for the delay, presses start then leaves the area.  This option allows more than one sampler to be set up to run, possibly with differing delays.  There are no concerns about which one may have started using the remote option.  The inbuilt audible alarm and LED advises the user when the sampler is running and when it has finished. Meaning they can promptly re-enter the space and continue with the sampling programme.



Most cleanroom suites have complex EM sampling plans with a large number of samples to be taken.  Any hold up in successful sampling because samplers have not run, is time consuming and costly, both in operator time and repeated entry to the suite.


Please don't hesitate to contact us if you would like more information or a quote on our SAS active air sampler range.



Andy Whittard,

Managing Director,

Cherwell Laboratories


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