How to set Cleanroom Alert and Action Limits as part of Microbiological Evaluation

B

BioBurden

#1
Hi Guys,

Back again to pick your brains.

We have a class VII cleanroom, approx. 4.5m x 4.5m.

We perform environmental monitoring on a monthly basis, "at rest".

Air plates, settle plates and contact plates.

Our limits are as follows:

Air Plates in Cleanroom - 100 (cfu/mould per m^3)
Air Plates in Airlock - 200

Settle Plates in Cleanroom - 100 (cfu/mould per plate)
Settle Plates in Airlock - 200

Contact Plates in Cleanroom - 25 (cfu/mould per 24cm^2)
Contact Plates in Airlock - 50

I know we should be testing while in use which is what we plan to do shortly.

However, I have been asked to set alert limits (below the above limits) and I have been unable to find any helpful information regarding any formula or method to define these limits.

Can anybody help?
 
Elsmar Forum Sponsor
B

BioBurden

#3
Re: How to set Cleanroom Alert and Action Limits as part of Microbiological evaluatio

So here are some of the calculations I have done based on the following historical data:
AIR PLATE SDA (mould/ m^3) - Class VII Cleanroom, at rest
JUN - 2
JUL A - 1
JUL B - 1 *2nd sampling performed due to spike in one area,
AUG - 22
SEP - 0
OCT - 0
NOV - 0

Mean: 3.714285714
STD DEV: 8.097618698
Pop STD DEV: 7.496938151

95% Confidence Interval (WARNING)
3.714285714 +/- 5.998689651
Upper Limit: 9.712975365 (Rounded up to 10)

99% Confidence Interval (ACTION)
3.714285714 +/- 7.883614549
Upper Limit: 11.59790026 (Rounded up to 12)

Does that seem right?

That would indicate that an investigation into August's results would have been necessary at the time despite it being well within the 100 specified limit for Class VII as set out in Eudralex.

Where am I going wrong?

 
B

BioBurden

#4
Re: How to set Cleanroom Alert and Action Limits as part of Microbiological Evaluatio

Am I supposed to be adding 2 or 3 Standard Deviations instead of the CI?
Have I just confused the situation by adding the CI into the calculations?
 
#5
Re: How to set Cleanroom Alert and Action Limits as part of Microbiological Evaluatio

Hi Bioburden,

For Poisson-distributed data, the alert limit may be set at the 95th percentile of the dataset, and the action limit at the 99th percentile.

For normally distributed data, the limits may be set at the average plus 2x standard deviation (equivalent to 95% probability) and 3x standard deviation (equivalent to 99.7% probability) respectively.

Refer to this execllent document for more info - http://www.pqg.org/pharma/wp-conten...trol-for-Non-sterile-Pharmaceuticals-2008.pdf
 
B

BioBurden

#6
Re: How to set Cleanroom Alert and Action Limits as part of Microbiological Evaluatio

So for the above example, I was correct in using the CI values to calculate?
It's definitely not normal distribution.

Sorry, just to clarify, I have no SPC software, I am just using Excel.
 
#7
Re: How to set Cleanroom Alert and Action Limits as part of Microbiological Evaluatio

So for the above example, I was correct in using the CI values to calculate?
It's definitely not normal distribution.

Sorry, just to clarify, I have no SPC software, I am just using Excel.
No issues ... you could take 2 SD and 3 SD for alert and action limits resp.
 
B

BioBurden

#8
Re: How to set Cleanroom Alert and Action Limits as part of Microbiological Evaluatio

Hi, just a quick question, returning to the decision process for Poisson or Normal.

I'm struggling to identify which distribution is which when charting the results using excel.

From the above document:
"The data should be plotted graphically to ensure the correct distribution is chosen for modelling. If the distribution is unknown, then the use of cumulative probability will allow limits to be calculated"


Also, from the above document:

"The decision regarding the approach to setting the appropriate limits should be captured in a written justification document."

What would this document need to include?
 
B

BioBurden

#9
Re: How to set Cleanroom Alert and Action Limits as part of Microbiological Evaluatio

Any answers for the previous post?

I have some more questions.

At what stage do I stop updating the limits based on historical data?

Once I have 12 months of data? i.e. 12 results.

Otherwise, if I keep using +2SD and +3SD, the process never goes out of control.

Does that sound right?
 
Thread starter Similar threads Forum Replies Date
R MSA on set of parts with low variation Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 20
A Need to calculate tolerance Intervals with a set of non-normal data and 3-Parameter Weibull distribution Using Minitab Software 0
P Best european location to set up for a virtual medical device manufacturer? EU Medical Device Regulations 4
S Is QMS like a set of rules and regulations that a company follows? ISO 13485:2016 - Medical Device Quality Management Systems 10
W Regarding Requirement for Hi pot & Leakage Current test Station Set-up IEC 60601 - Medical Electrical Equipment Safety Standards Series 6
G CE marking of MD and IVD set EU Medical Device Regulations 3
J How to Set Microbial Limits in Food Supplements Food Safety - ISO 22000, HACCP (21 CFR 120) 3
qualprod To set frequency to review documents in ISO 9001 7.5? Document Control Systems, Procedures, Forms and Templates 13
M IATF 16949 8.5.1.3 Verification of job set-ups - Do we need secondary check? IATF 16949 - Automotive Quality Systems Standard 7
B Set RH spec from dewpoint spec General Measurement Device and Calibration Topics 2
S Is Optical Parallel Set required calibration? ISO 17025 related Discussions 1
R Gauge R&R on pre-set torque wrench Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 2
A How to set up Continuous CpK monitoring of an injection mold process Reliability Analysis - Predictions, Testing and Standards 7
N Internal Audit Schedule – Who gets to set the schedule? Internal Auditing 16
G Comparing Gauge Blocks - Translating the calibration between the master set and the QA set General Measurement Device and Calibration Topics 2
L How to evaluate the process capability of a data set that is non-normal (cannot be transformed and does not fit any known distribution)? Capability, Accuracy and Stability - Processes, Machines, etc. 14
N When to record values if a spec for a mfg process is set Manufacturing and Related Processes 3
Marc Time Zone - Set your Time Zone Elsmar Xenforo Forum Software Instructions and Help 1
D As a newcomer to QMS, I really appreciate how ISO is set up. ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 3
C IATF 16949 Cl 8.5.1.3 - Verification of job set up IATF 16949 - Automotive Quality Systems Standard 4
D How to set equipment calibration/verification criteria General Measurement Device and Calibration Topics 1
S GRR on ID with set of pin gauges Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 4
G What to Check - Set Up vs. In Process Inspections Inspection, Prints (Drawings), Testing, Sampling and Related Topics 6
N The known set of all root causes Nonconformance and Corrective Action 11
G What degrees of freedom means in uncertainty budget and how do I set the value Measurement Uncertainty (MU) 2
D What is the exact Temperature Coefficient Value to be set on a Conductivity Meter? General Measurement Device and Calibration Topics 2
G Training Employees about Quality - Philosophy / Mind set Misc. Quality Assurance and Business Systems Related Topics 1
renenatasha MDD Classification for Pressure Monitoring Set CE Marking (Conformité Européene) / CB Scheme 1
U Are all manufacturers required to set up eMDR system? Other US Medical Device Regulations 4
S Gage Block Verification or buy a new set (cost aspect) General Measurement Device and Calibration Topics 1
E How to use the Standard Error and how to set the error limits? Reliability Analysis - Predictions, Testing and Standards 2
C Implementing a set of bore gages at a machine Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 1
S How to set up the Accupoint 2 ATP sanitation monitoring system Quality Assurance and Compliance Software Tools and Solutions 1
L How do I set a limits to cfu in an ISO class 7 Clean Room? ISO 13485:2016 - Medical Device Quality Management Systems 2
4 Quality vs Production on CMM Set Up Requirements Manufacturing and Related Processes 1
A What is the definition of Installation that requires Record Keeping vs Set-up 21 CFR Part 820 - US FDA Quality System Regulations (QSR) 4
G AS9120 - What should we be expecting once we set forth into becoming certified? AS9100, IAQG, NADCAP and Aerospace related Standards and Requirements 11
C ISO 9001:2008 Audit Major Finding - Dial Calipers not set to zero ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 16
A IEC 60601-2-24 Question: Free Flow Clamp on Set? IEC 60601 - Medical Electrical Equipment Safety Standards Series 5
C Lowest Acceptable Grade for Master Gage Set Calibration and Metrology Software and Hardware 1
L How to set up a basic electronic test equipment calibration laboratory General Measurement Device and Calibration Topics 3
Q Inquire TS 16949 standard - Clause 7.5.1.3 Verification of 'Job Set-Up' IATF 16949 - Automotive Quality Systems Standard 8
M AS9100C Document Control for Machine Set Up Work Instructions AS9100, IAQG, NADCAP and Aerospace related Standards and Requirements 4
J Appropriate In-Process Monitoring Frequency for 2X per day Change Set-Up. Statistical Analysis Tools, Techniques and SPC 3
S Insufflation Tubing & Filter Set Product Classification question 21 CFR Part 820 - US FDA Quality System Regulations (QSR) 7
M New Calibration Laboratory Set Up Measurement Parameters and Equipment General Measurement Device and Calibration Topics 4
F How to set-up a Dual Company QMS (Quality Management System) Quality Manager and Management Related Issues 2
R Can the same Biocompatibility Report for Infusion Set be used for its Components? ISO 13485:2016 - Medical Device Quality Management Systems 7
insect warfare How is the Management Review structure of your company set up? Management Review Meetings and related Processes 5
AnaMariaVR2 Legal Flash: 8 Regulations set to impact the Pharma & Biotech Industry in 2013 US Food and Drug Administration (FDA) 0

Similar threads

Top Bottom