Maximum workplace concentrations

In general, the primary aim of defining maximum workplace concentrations is to protect workers’ health, based on scientifically sound evidence.

In Germany, MAK (‘Maximale Arbeitsplatzkonzentration’: maximum workplace concentration) values are derived by the DFG Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area, better known as the MAK Commission. This independent body has been mandated by the German Research Foundation (DFG) to determine the current state of research relating to the health risks posed by substances and materials used in the workplace, and to advise public authorities accordingly. The most important practical results of the Commission’s work are scientific recommendations for the establishment of MAK values and BAT values (biological tolerance values for occupational exposure), for the classification of carcinogenic, embryotoxic/fetotoxic substances and germ cell mutagens, and for the evaluation of measurement methods. The recommendations are freely available online (see Further reading).

Irritant gases  
High water solubility, e.g. ammonia, sulfur dioxide, hydrogen chloride
Moderate water solubility, e.g. chlorine, hydrogen sulfide
Low water solubility, e.g. ozone, nitrogen dioxide, phosgene
Organic chemicals  
Organic acids, e.g. acetic acid
Aldehydes, e.g. formaldehyde, acrolein
Amines. e.g. hydrazine, chloramines
Tear (CS) gas, mustard gas
Organic solvents, including some leather sprays
Some agrochemicals (paraquat, cholinesterase inhibitors)
Metallic compounds  
Mercury vapours
Metallic oxides, e.g. those of cadmium, vanadium, manganese, osmium
Halides, e.g. zinc chloride, titanium tetrachloride, antimony pentachloride, uranium hexafluoride
Nickel tetracarbonyl
Hydrides of boron, lithium, arsenic, antimony
Metal fumes
Complex mixtures  
Smoke from fires
Pyrolysis products from plastics
Solvent mixtures
Spores and toxins from microorganisms
Polymer fumes
Table 1 – Causes of chemical pneumonitis.

At the European level, the European Commission has set up the Scientific Committee on Occupational Exposure Limit Values (SCOEL), with a mandate to advise the Commission on occupational exposure limits for chemicals in the workplace. It does this by preparing scientific recommendations for the Commission, which are used to underpin regulatory proposals on occupational exposure limit values (OELVs) for chemicals in the workplace. During this procedure, draft recommendations from SCOEL undergo a stakeholder consultation to allow interested parties to submit health-based scientific comments and further data.

  Healthcare workers Other occupations
Airborne, viral
Varicella All  
Measles Physicians and nurses  
Rubella All  
Mumps Paediatricians and dentists  
Pertussis All  
Parvovirus B19 infection Nurses  
RSV infection All  
Adenovirus infection Staff in ophthalmology clinics,
intensive care units and longterm
paediatric care
Influenza Physicians and nurses Office workers
SARS-coronavirus A Physicians, nurses, healthcare
assistants and others; nursing
home attendants; housekeeping
personnel, laboratory workers
Transport workers, business
travellers, market for exotic
Avian influenza H5N1 Physicians, nurses, healthcare
Poultry, farm and market
Mycoplasma infection All  
Airborne, bacterial
Tuberculosis Nurses, physicians, pathologists,
laboratory workers, housekeeping
Anthrax Hospital supply Agricultural workers, wool
sorters, mail sorters
Psittacosis   Turkey processing
Blood-borne, viral
HIV infection Physicians, nurses, dental
workers and dentists, laboratory
workers, technicians in dialysis
unit, respiratory therapists
Embalmers or mortuary
Ebola infection Nurses  
Table 2 – Respiratory infections that may be occupationally acquired. RSV: respiratory syncyntial virus; SARS: severe acute respiratory syndrome. Reproduced from Ho et al ., 2007, with permission from the publisher.

Recommendations adopted by the SCOEL are also available online (see Further reading).

In the USA, threshold limit values (TLVs) and biological exposure indices (BEIs), as defined by the American Conference of Governmental Industrial Hygienists, are determinations made by a voluntary body of independent knowledgeable individuals. They represent the opinion of the scientific community, after reviewing the available data, that exposure at or below the level of the TLV or BEI does not create an unreasonable risk of disease or injury (see ).

High-molecular-weight agents  
Acarians (ticks, mites)
Animal-derived antigens
Biological enzymes
Crustacea, seafood, fish
Plant-derived natural products
Vegetable gums
Low-molecular-weight agents  
Aliphatic amines (ethyleamines and others)
Aromatic amines
Quaternary amines
Reactive dyes
Wood dust or bark
Various chemicals
Table 3 – Causes of occupational asthma.
Man-made vitreous fibres
Oil mist
Portland cement
Steel dust
Organic dusts  
Firefighting exposures
Sulfur dioxide
Welding fumes
Environmental tobacco smoke
Table 4 – Agents which, under poor occupational hygiene conditions, may cause occupational bronchitis and chronic obstructive pulmonary diease.

See the entire Occupational risk factors Chapter