Occupational Exposure Monitoring
Introduction
We have over 25 years experience in occupational exposure monitoring at premises involved in the manufacture or use of paints, printing inks, plastics and adhesives. Although we are a Member based organisation located in the UK, our services are also available to non-Members worldwide.
We have carried out occupational exposure monitoring for firms manufacturing:-
- paints
- resins
- polymers
- printing inks
- automotive components
- military vehicles
- aircraft parts
- office furniture
- graphic art materials
- rubber goods
- computer hardware
Our overall objective is to assist firms in complying with Safety, Health, and Environmental legislation, while maintaining or improving process efficiency. We recognise that our clients need us to find solutions, rather than just define problems and we are fortunate in being able to call upon the extensive experience within the Association of all aspects of surface coating technology.
The services described on this page relate to monitoring carried out in the workplace. Those interested in monitoring emissions from a factory should visit our Stack Emission Monitoring page.
We measure both air quality and the efficiency of equipment:
| Measuring Air Quality | Measuring Equipment Efficiency |
|---|---|
|
Volatile Organic Compounds (VOC's) Particulates Isocyanates |
Local Exhaust Ventilation (LEV) Respiratory Protective Equipment (RPE) Spray Booths Spray Guns |
Measuring Air Quality
We can measure the concentration of air pollutants in the general working atmosphere and in the breathing zone of selected operators:-
Volatile Organic Compounds (VOC's)
We can carry out these measurements at static points or within the breathing zone of operators. Depending on the circumstances, we collect samples using either an adsorption tube-pump combination or diffusive tubes.
The absorption tube method is carried out in accordance with MDHS 96 "Volatile organic compounds in air (4)" (2000) while the diffusive tube method follows the basic principles of MDHS 80 "Volatile organic compounds in air" (1995). In either case the tubes are returned to a UKAS accredited laboratory where they are desorbed and the volatiles identified and quantified using gas chromatography.
Particulates
We can collect total or respirable particulates using static or breathing zone sampling techniques. Both methods involve the use of a pump-filter combination with the filter being weighed to determine the amount of particles collected from a measured volume of air. In the case of respirable particulate determination, a cyclone device is used to prevent non-respirable sized particles reaching the filter.
All particulate determinations are carried out using the principles for personal sampling given in MDHS 14/3 "General methods for the gravimetric determination of respirable and total dust" (2000).
Isocyanates
Isocyanate concentrations are measured in accordance with MDHS 25/3 "Organic isocyanates in air" (1999). This involves drawing a measured volume of air through a filter impregnated with 1-(2-methoxyphenyl) piperazine reagent. The filter is then returned to a UKAS accredited laboratory where the concentration of free isocyanate groups is determined using high performance liquid chromatography (HPLC).
Measuring Equipment Efficiency
It is vital that ventilation and respiratory protection equipment used in the workplace is fit for the purpose, correctly operated and properly maintained. Our tests are designed to address all of these points.
Local Exhaust Ventilation (LEV)
The main function of a LEV system is to reduce the concentration of hazardous materials in the working atmosphere to a level where they do not present a threat to the health and safety of workers. In order to be effective, a LEV system must be well designed and constructed, properly used and maintained in good condition. Performance and efficiency can be impaired by blockages and/or leaks in the ductwork or by the build up of contaminants.
We carry out tests with the aim of establishing whether the LEV system meets basic design criteria and is operating effectively. The test are carried out in accordance with the principles given in the HSE guidance document HS (G) 54 "Maintenance, examination and testing of local exhaust ventilation" (1998). This involves measuring the extract face velocity using a rotating vane anemometer. In addition, the static pressure in the ducts is measured at various points using a micro-manometer.
Respiratory Protective Equipment (RPE)
One of the most valuable services that we offer in this area is a comprehensive assessment of the way in which RPE is selected, used and maintained. The current COSHH code of practice states that a thorough examination and where appropriate, testing of RPE should take place at least once a month and more frequently where conditions are particularly severe. The inspection, maintenance and testing of RPE should be carried out by trained personnel and a proper records of these activities should be kept.
The use of appropriate RPE is especially important when two-pack polyurethane coatings and other potential respiratory allergens are used
We can measure the quality of air supplied to air-fed masks and helmets using colorimetric detector tubes. Substances monitored include water vapour, carbon monoxide, carbon dioxide and oil mist.
Spray Booths
During paint spraying operations the whole paint is transformed to a mixture of VOC's and particles and consequently is potentially both respirable and ingestible. If the coating contains flammable solvents, there is also a risk that the mixture of vapour and particles will exceed the lower explosive limit (LEL).
We can carry out a number of checks on spray booths. A smoke test will reveal any regions within the booth where air is either stagnant of recirculating. We would then use an explosimeter to measure the flammable vapour concentration in these regions in order to check that it was less than 25% of the LEL. We would also measure the extract face velocity using a rotating vane anemometer and compare this value with the minimum recommended value given in the HSE guidance document HS (G) 54 "Maintenance, examination and testing of local exhaust ventilation" (1998).
From a knowledge of the extraction rates together with the paint and the spraying conditions used, we are able to estimate the potential VOC, particulate and (where appropriate) the isocyanate concentrations.
Spray Guns
When a paint is spray-applied, all the VOC's and a proportion of the particles leaving the gun are destined to become air pollutants. A well designed and correctly operated spray gun will produce a minimum amount of paint overspray.
We can measure how efficient spray guns are at transferring paint to the object being coated ( as opposed to transferring it to the atmosphere or to surrounding structures). We follow the general principles of ASTM D5286-95 "Determination of transfer efficiency under general production conditions for spray application of paint".
The test is normally carried out using a paint and a spray booth which are representative of the client's normal production process. Metal test panels are weighed before and after paint is spray-applied. The weight of the paint leaving the nozzle of the gun is measured and the non-volatile content of the paint is determined. Using these values it is then possible to calculate the weight of the paint on the test panels as a percentage of the weight of paint that was discharged from the gun. This value is the spray gun transfer efficiency. A minimum value of 65% is recommended in the Process Guidance Notes PG 6/23 "Coating of metal and plastics" (1997) and PG 6/34 "Respraying of road vehicles" (1997).
Consultancy Services
In addition to measuring air quality and equipment efficiency, we will be pleased to advise on the most efficient and cost effective methods of complying with the appropriate legislation and guidelines. In particular our consultant can tell you about the advantages and limitations of:-
- changing the operational procedures
- using alternative materials
- installing or modifying ventilation equipment
We are very experienced with working for small companies where money is simply not available for re-equipping the factory or installing state of the art ventilation equipment. We can usually suggest a practical, low-cost solution that will enable you to maintain production and work within current emission limits.
