Hygiene Risks
2. Chemical Pollutants
Chemical pollutants are understood as substances which, in the form of dust, smoke, gases or fumes, are released into the work atmosphere as a consequence of their manipulation or of being generated during work processes. These may result in disorders to the health of those people exposed to them if they are present in sufficient amounts.
The following chart shows a classification of chemical pollutants on the basis of their damaging effects on health.
| EFFECT | CHARACTERISTIC | POLLUTANTS | |
|---|---|---|---|
| Pneumoconiotic | Reduces the amount of air inhaled | Silica, Carbon, Asbestos | |
| Corrosive | Corrosive action on tissue | Acids, Alkalis | |
| Irritant | Irritation of the skin or respiratory tract | Ammonium, ozone, chrome | |
| Sensitizing agent | Allergies in sensitive individuals: dermatitis, etc. | Cement, Wood dust | |
| Narcotic - Anaesthetic | Acts on the central nervous system | Solvents in general | |
| Asphyxiant | Simple | Displaces the oxygen in the air | Carbon dioxide, Butane |
| Chemical | Hinders the transport of oxygen | Carbon monoxide, Cyanides | |
| Carcinogen | May produce cancer | Benzene, Asbestos, Arsenic | |
| Systemic Toxic | Damaging alterations in organs or systems | Lead, Manganese, Mercury | |
As overexposure to chemical pollutants may give rise to different occupational diseases, it is necessary to know the concentrations of these pollutants in the work atmosphere and hence to be able to compare them with standard values drawn up by the competent bodies, with the aim of assessing the situation in each case.
The standard values for industrial hygiene most widely used in Spain since the 1970’s have traditionally been Threshold Limit Values (TLV) drawn up according to US standards, established by the American Conference of Governmental Industrial Hygienists (ACGIH).
Since the end of the 1990’s, however, as a result of the development of community regulations in this respect, the trend in Spain has been to begin to use the values proposed by the INSHT (Spanish National Institute of Safety and Hygiene at Work) in their corresponding Technical Guides, called Ambient Limit Values or ALV. A distinction is made between:
- ALV-DE (Ambient Limit Values for Daily Exposures): The average concentration value, weighted with respect to 8 hours (regardless of the effective duration of the worker’s exposure to the pollutant). Below the ALV-DE, it is considered that the worker can remain exposed 8 h/day, 40 h/week during his working and post-working life without suffering any derived effect.
- ALV-SE (Ambient Limit Values for Short Exposures): The average concentration value, weighted with respect to 15 minutes. This contemplates the possibility that a short exposure to the pollutant may trigger effects that may be harmful to the worker (which depends on the degree of accumulation of the substance in his organism, conditional on its respective absorption-elimination rate).
It should be noted that not all the substances referenced by the INSHT have two values, i.e. ALV-SE and ALV-DE. Nevertheless, for the same substance, its ALV-DE will always be equal to or less than its ALV-SE.
For those cases in which a pollutant does not have an assigned ALV-SE, maximum reference concentrations have been defined. These are known as Excursion or Deviation Factors:
- Factor 5 times the ALV-DE: A value that cannot be exceeded at any time whatsoever throughout the working day.
- Factor 3 times the ALV-DE: A value that must not be exceeded throughout the working day for a total time of 30 minutes. One or more exposures above this concentration may occur throughout the working day, but they must never exceed 30 minutes in any one day.
It should be borne in mind that the ALV are established by exclusively taking into consideration the respiratory tract as the form of entry into the organism. Nevertheless, those pollutants with a capacity to penetrate the organism via the skin are identified by means of the note “via the skin”.
