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Hi all, A newly pregnant lady at work has had high levels of carbon monoxide diagnosed. She works in a vehicle maintenance workshop that is fitted with regularly serviced LEV. A healthcare worker is going to test her before and after work in the coming days to try to identify if that's where it is coming from. Carbon Monoxide is in EH40 and my employer wants to assess whether the LEV is actually doing its job during real use, both now and on an ongoing basis. There is a suspicion that workers aren't always using the LEV on car exhausts.
Can anyone point me towards how I can measure the carbon monoxide workers are exposed to? I thought some air sampling or a dosemeter, but every search result comes up with Carbon Monoxide montiors for the home. Thanks
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Rank: Super forum user 
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Best thing is to engage the services of a qualified occupational hygienist who will not only do the measurements, but inspect the workplace and advise on the interpretation of the results. Edited by user 04 May 2021 13:11:18(UTC)
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 1 user thanked Kate for this useful post.
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Kate gives good advice. On another hand, a few years back in a very large office building we had suspicions that the air conditioning system was not operating sufficiently to provide an adequate supply of fresh air to all staff - despite the assurances of the building management company.
Our response was to purchase an air sampling pump (search for Gastec or Draeger) - simply a reverse operation tyre pump but rather better made and pumping an assured volume on each stroke. This cost at the time around £150. These pumps require sampling tubes to operate - we purchased tubes to target CO2 and other substances that we wished to monitor - at around £20 for 10 so you are talking £2 per test plus time to operate and collate results. Since those days electronic sampling devices are available but I cannot comment as to their accuracy. Such monitoring tubes are available for CO but the 2 makes are not compatable with each other so you have to make a decision. Constant monitoring devices that can be fitted to a wall are also available. But perhaps your first step could be to make several walk throughs of the workshop and observe whether the LEV is in place and operational
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2 users thanked martynp1000 for this useful post.
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Using a standard CO monitor will give you a starting point of what the actual CO levels are within the workshop, they will not measure individual exposure but that shouldnt be necassary if overall levels are low where tested.
Some medical conditions lead to high CO blood levels that are not caused by CO in the atmosphere!
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1 user thanked Dazzling Puddock for this useful post.
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well here is a link to one manufacturer https://www.draeger.com/en_uk/Substances/255 other manufacturers are also available
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as said turn up and have a look and see what they are doing. Ask them what they think carbon monoxide does to you.
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what has the statutory inspection of the LEV shown? If they are not taking background levels of CO during the inspection how do they know its working effectively?
You may already have all the information you require without doing more checks. There are lots of gas meters out there (google hand held co meters) but actualy working out the occupational exposure limit is is not always easy -back to Kates original suggestion
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Rank: Forum user
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Originally Posted by: martynp1000  Kate gives good advice. On another hand, a few years back in a very large office building we had suspicions that the air conditioning system was not operating sufficiently to provide an adequate supply of fresh air to all staff - despite the assurances of the building management company.
Our response was to purchase an air sampling pump (search for Gastec or Draeger) - simply a reverse operation tyre pump but rather better made and pumping an assured volume on each stroke. This cost at the time around £150. These pumps require sampling tubes to operate - we purchased tubes to target CO2 and other substances that we wished to monitor - at around £20 for 10 so you are talking £2 per test plus time to operate and collate results. Since those days electronic sampling devices are available but I cannot comment as to their accuracy. Such monitoring tubes are available for CO but the 2 makes are not compatable with each other so you have to make a decision. Constant monitoring devices that can be fitted to a wall are also available. But perhaps your first step could be to make several walk throughs of the workshop and observe whether the LEV is in place and operational
Thanks, I suspect there is an element of lazy technicians not putting the LEV on. An air quality monitor which measure CO which seem a sensible approach. My aim is to work out whether the workplace is anywhere near the CO WEL, if we have an issue then it's back to the LEV company to ask why their kit is not doing its job.
I'm not entirely sure we need to engage an occupational hygienist yet, I'm not sure what value they would add, however if I'm missing something then please let me know.
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Originally Posted by: Brian Hagyard what has the statutory inspection of the LEV shown? If they are not taking background levels of CO during the inspection how do they know its working effectively?
You may already have all the information you require without doing more checks. There are lots of gas meters out there (google hand held co meters) but actualy working out the occupational exposure limit is is not always easy -back to Kates original suggestion
Thanks, I'll ask them to dig out the LEV report to see what their methodology and results are. The technique and examples for working out occ exposure in EH40 seems relatively straightforward, am i missing something?
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Rank: Super forum user 
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Does the workshop not already have a CO measurement device (part of an exhaust gas tester for tuning / MOT)? Is the person in question a smoker? A personal habit can have a marked impact on CO levels.
So can poorly set-up / maintained domestic gas appliances.
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Rank: Super forum user
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Does the workshop not already have a CO measurement device (part of an exhaust gas tester for tuning / MOT)? Is the person in question a smoker? A personal habit can have a marked impact on CO levels.
So can poorly set-up / maintained domestic gas appliances.
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Originally Posted by: Roundtuit Does the workshop not already have a CO measurement device (part of an exhaust gas tester for tuning / MOT)? Is the person in question a smoker? A personal habit can have a marked impact on CO levels.
So can poorly set-up / maintained domestic gas appliances.
Not a smoker & gas appliances are located in a different part of the building. Good idea about the Carbon Monoxide monitor though!
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Rank: Super forum user
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Thanks, I'll ask them to dig out the LEV report to see what their methodology and results are. The technique and examples for working out occ exposure in EH40 seems relatively straightforward, am i missing something?
hard to say as you have not set out your methodology. Exposure limits are for the person - so the only real way of doing it is via dose meters. If you set up static monitoring then how do you know how long people spend in that location? You might be looking at where you think the worst case cenario may be if someone spent 8 hours in one spot - but can you be sure, and how do you know the day or time you choose is representative.
Personaly i have found it cheeper to bring in an occupational hygienist when looking at exposure levels and let tje work out all teh parametors - even then they have often hired the monitoring equipment as its cheeper than buying thier own.
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1 user thanked HSSnail for this useful post.
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Originally Posted by: Brian Hagyard
Thanks, I'll ask them to dig out the LEV report to see what their methodology and results are. The technique and examples for working out occ exposure in EH40 seems relatively straightforward, am i missing something?
hard to say as you have not set out your methodology. Exposure limits are for the person - so the only real way of doing it is via dose meters. If you set up static monitoring then how do you know how long people spend in that location? You might be looking at where you think the worst case cenario may be if someone spent 8 hours in one spot - but can you be sure, and how do you know the day or time you choose is representative.
Personaly i have found it cheeper to bring in an occupational hygienist when looking at exposure levels and let tje work out all teh parametors - even then they have often hired the monitoring equipment as its cheeper than buying thier own.
Thanks, I appreciate the cost may seem low but we have a lot of sites across the region so it will soon ramp up. Methodology - I would carry out a basic survey during a busy period, setting up the monitoring equipment for a full shift on the post of the vehicle ramp at head height - staff don't routinely work at the back of the car when it is running so the monitor would be closer than they were to the point of emission. Also the technicians all work on their own ramps, very rarely do they work on other ramps.
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Originally Posted by: Eddie Caballo Originally Posted by: Brian Hagyard
Thanks, I'll ask them to dig out the LEV report to see what their methodology and results are. The technique and examples for working out occ exposure in EH40 seems relatively straightforward, am i missing something?
hard to say as you have not set out your methodology. Exposure limits are for the person - so the only real way of doing it is via dose meters. If you set up static monitoring then how do you know how long people spend in that location? You might be looking at where you think the worst case cenario may be if someone spent 8 hours in one spot - but can you be sure, and how do you know the day or time you choose is representative.
Personaly i have found it cheeper to bring in an occupational hygienist when looking at exposure levels and let tje work out all teh parametors - even then they have often hired the monitoring equipment as its cheeper than buying thier own.
Thanks, I appreciate the cost may seem low but we have a lot of sites across the region so it will soon ramp up. Methodology - I would carry out a basic survey during a busy period, setting up the monitoring equipment for a full shift on the post of the vehicle ramp at head height - staff don't routinely work at the back of the car when it is running so the monitor would be closer than they were to the point of emission. Also the technicians all work on their own ramps, very rarely do they work on other ramps.
Having had a quick google I've found these which look like a much better idea: https://tinyurl.com/vxn9ru4z I think for assessing whether we are exceeding the WEL these seem like a good solution when combined with the method for calculating exposure in EH40. Clearly every day is different, however choosing a busy period where the workshop doors are shut would seem a reasonable approach to simulate worst case scenarios. If the results show an issue then we can investigate further.
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So the LEV test report says that each hose has an allowance of 144 m3/h for 'Light Commercial (Vans)', then uses face velocity to calculate the volume extraction. Most of the hoses are running at 200 m3/h, hence they all pass. Not sure where the 144 comes from?
It was mentioned above that they should be measuring background levels of CO in order to know if the LEV is working, however there is nothing about this in the report. My experience of fume cupboard commissioning is checking face velocity, pressure checks and stack disharge velocity hence the above seems a reasonable approach to me. Can anyone advise is the LEV company carrying out a sufficient test? Should they also be checking background CO levels?
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Thanks all, we had a specialist come and carry out air monitoring in the end. LEV checked out fine and no CO found in workshop. Use of LEV reinforced to staff and supervisors.
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1 user thanked Eddie Caballo for this useful post.
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Carbon monoxide is produced within the body. In low levels in the majority of people, but several conditions may lead to an increase in the levels of carbon monoxide. It's called endogenous carbon monoxide production. https://journals.physiol.../japplphysiol.00174.2012
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"Thus endogenously produced carbon monoxide is not, as was once supposed, simply a potentially toxic waste product of metabolism but is involved in many physiological functions, including regulation of respiration [5], neuronal signaling [6], regulation of blood pressure [7] and uterine contraction during pregnancy [8]" https://pubmed.ncbi.nlm.nih.gov/9486963/
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