55
Mike Slater
| Date post: | 12-May-2015 |
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Health & Medicine |
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Mike Slater
This Slideshare version of the presentation includes some additional explanatory text not included on the original slides
Recognition Evaluation Control
Recognition Evaluation Control
Occupational hygiene is about preventing ill health at work
Recognition Evaluation Control
Measuring exposure to hazardous substances can be an important part of that process
A new Workplace Exposure Limit (WEL) has recently been introduced for sulphuric acid mist
It’s the first limit to be specified as the thoracic fraction
The “thoracic fraction” includes those particles that can deposit in the regions of the respiratory system coloured blue and pink on this diagram
Image Source: http://www.skcinc.com
Criteria for selecting a suitable method:
Specificity
Criteria for selecting a suitable method:
Specificity
Criteria for selecting a suitable method:
No interferences from other compounds that may be present
Specificity
Sensitivity
Criteria for selecting a suitable method:
Specificity
Sensitivity
Criteria for selecting a suitable method:
preferably can detect concentrations as low as 1/10th of the WEL (i.e. 0.005mg/m3)
Specificity
Sensitivity
Thoracic fraction
Criteria for selecting a suitable method:
Specificity
Sensitivity
Thoracic fraction
Personal sampling
Criteria for selecting a suitable method:
BS ISO 21438-1: 2007
Workplace atmospheres – Determination of inorganic acids by ion chromatography, part 1: Non-volatile acids (sulphuric acid and phosphoric acid)
BS ISO 21438-1: 2007
Workplace atmospheres – Determination of inorganic acids by ion chromatography, part 1: Non-volatile acids (sulphuric acid and phosphoric acid)
The method commonly used in the UK
BS ISO 21438-1: 2007
Workplace atmospheres – Determination of inorganic acids by ion chromatography, part 1: Non-volatile acids (sulphuric acid and phosphoric acid)
This collects the inhalable fraction
Source:www.tsi.com
Particulates
Inhalable Thoracic Respirable
Particulates
Inhalable Thoracic Respirable
Lets look at the methods used to collect the different fractions
Particulates
Inhalable Thoracic Respirable
Inhalable Fraction
7 hole head IOM head
Operate at 2 litres/minute
Filter cassette
I.O.M sampler
The common sampler used in the UK
BS ISO 21438-1: 2007
Workplace atmospheres – Determination of inorganic acids by ion chromatography, part 1: Non-volatile acids (sulphuric acid and phosphoric acid)
Collects the inhalable fraction
Particulates
Inhalable Thoracic Respirable
Respirable Fraction
Source: http://www.skcinc.com
The cyclone sampler
Particulates
Inhalable Thoracic Respirable
Thoracic Fraction
Thoracic Fraction
A universal method has not been established
Thoracic Fraction
So let’s look at some possible options
Respirable - Thoracic Cyclones
Source: www.bgiusa.com/ihi/hfrtc.htm
This sampler is used for oil mist in the USA
Parallel Particle Impactor Size-selective Samplers for Thoracic or Respirable Particulates
Source: http://www.skcinc.com/prod/225-380.asp
So what are the options for sampling sulphuric acid mist?
Specificity
Sensitivity
Thoracic fraction
Personal sampling
Criteria for selecting a suitable method:
Nyrstar method
Staplex Model TFIA-2F high volume sampler with 4-inch diameter filter
Nyrstar method
Not personal sampling
Nyrstar method
Not thoracic fraction
Nyrstar method
Specificity
Sensitivity
Thoracic fraction
Personal sampling
Source:www.tsi.com
Option 1
Sample for inhalable fraction
BS ISO 21438-1: 2007
Specificity
Sensitivity
Thoracic fraction
Personal sampling
BS ISO 21438-1: 2007
Specificity
Sensitivity
Thoracic fraction
Personal sampling
The problems with interferences can be overcome
Option 1
Sample for inhalable fraction
This approach will overestimate the thoracic fraction
Option 1
Sample for inhalable fraction
But if results lower than 0.05 mg/m3, then the thoracic concentration will be well below the limit
Option 1
Sample for inhalable fraction
If results substantially higher than 0.05 mg/m3, then it is likely that the limit will be exceeded
Option 1
Sample for inhalable fraction
But results will be difficult to interpret if they are just above 0.05 mg/m3
Option 2
Develop and validate a method for the thoracic fraction of sulphuric acid mist
Option 2
Develop and validate a method for the thoracic fraction of sulphuric acid mist
Method development and validation will be expensive
Option 2
Develop and validate a method for the thoracic fraction of sulphuric acid mist
I think it is unlikely that HSE will fund this
Other important considerations
Correcting for background sulphate
Sampling strategy
Interpreting results
[email protected] www.diamondenv.co.uk http://diamondenv.wordpress.com www.slideshare.net/mikeslater Twitter @diamondenv
Mike Slater
Mike Slater, Diamond Environmental Ltd. ([email protected])
This presentation is distributed under the Creative Commons Attribution-NonCommercial-ShareAlike
UK:International Licence
