The human body can become damaged due both to an insufficiency of oxygen in the air and due to the presence of hazardous substances.
An insufficiency of oxygen can cause permanent damage to cerebral cells and even cause death. If the body absorbs hazardous substances, according to the specific way these substances react (physical, chemical or combined), they can cause pulmonary illnesses, acute or chronic intoxications, radiation damage, different types of tumours or other damage (for example allergies). The type of damage depends generally on the concentration and length of the effect of hazardous substances on one’s health, how it entered into the body (for example deposits in the lungs, absorption through blood), on the fatigue caused by work performed, by the frequency and volume of respiration as well as particular physical conditions of persons.
Respiratory tract protection equipment (APVR) can be utilised to avoid these problems. Before taking into consideration the use of an APVR, in as much as possible and "in relation to acquired knowledge on the basis of technical progress" containment of the pollutants suspended in air must be made, with use of engineering methods (for example systems of confinement, aspiration systems). If said objective cannot be reached or if, by means of technical or organisational measurements, these objectives can be reached only insufficiently, it is therefore best to make suitable APVR available for each specific purpose, and to ensure appropriate use, storage and maintenance. It is important to select the proper type of APVR between the many available types and to choose that which complies with specific norm requirements. Use of the wrong type can be dangerous. It is also important that all persons for which APVR use is required be appropriately trained, instructed on use and, if necessary, subject to a medical exam. The function of an APVR consists in filtering the polluted atmosphere or in supplying breathable air from an alternative source. The air reaches the user by means of a mouthpiece, a full semi-mask, a helmet, a hood. Sources of hazards for the respiratory tract include: insufficient oxygen, extreme temperatures and the presence of contaminating substances in the environmental air.
Contaminants can be sub-divided as follows:
- dust: fine particles generated by crushing of solid materials
- dust: miniscule liquid drops with organic or water bases which create spray operations
- steam: very fine solid particles, formed when melting or vaporising metal which cools down rapidly
- gas: substance in aeriform pressure phase and at room temperature
- vapour: gaseous form of substance which, at room temperature, are found in the liquid or solid state
RESPIRATORS WITHOUT MAINTENANCE FOR DUSTS – TECHNICAL DEFINITIONS
Type and class
A symbol indicating the type of device and protection level offered, for example FFP2: dust respirator for face piece filtration of class 2, where class 2 indicates the protection level.
Maximum use level
Quantità massima di contaminante nell’aria per la quale si può utilizzare il respiratore; il dato è di solito espresso come multiplo della concentrazione accettabile sul luogo di lavoro.
TLV (Threshold Limit Value)
The average weighted concentration over time (considering an average working day of 8 hours and an average work week of 40 hours) during which it can be assumed that almost all workers can be continually exposed day after day, without negative effects on health, measured in milligrams per metre squared for dust and parts per million for gas and vapours.
NORM LIST FOR RESPIRATORY TRACT:
UNI EN 132:2000 Respiratory tract protection equipment – Definition of terms and pictograms
UNI EN 134:2000 Respiratory tract protection equipment - Nomenclature of components
UNI EN 136:2000 Respiratory tract protection equipment – Full masks – Requirements, tests, marking
UNI EN 140:2000 Respiratory tract protection equipment – Half and quarter masks - Requirements, tests, marking
UNI EN 14387:2004 Respiratory tract protection equipment – Anti-gas and combined filters - Requirements, tests, marking
UNI EN 143:2002 Respiratory tract protection equipment – Anti-dust filters - Requirements, tests, marking
UNI EN 149:2003 Respiratory tract protection equipment – Filtration semi-masks against particles - Requirements, tests, marking
Anti-dust filters (ideal for protection from dust and fibres, smoke and steam)
European norms UNI EN149:2003 (for anti-dust facial filtrations) and UNI EN 143:2002 (for anti-dust filters of rubber masks) define three different protection classes, with total increase filtration efficiency:
1 Type P1 filters: for protection from non-toxic (dust) aerosol in concentrations up to 4 times the TLV (Threshold Limit Value)
2 Type P2 filters: for protection from low/medium toxic aerosol (particle) in concentrations up to 10 times the TLV (16 x TLV if mounted on the full face piece).
3 Type P3 filters: for protection from low/medium/high toxic aerosol and radioactive aerosol (particles) in concentrations of up to 30 times the TLV (200 x TLV if mounted on the full face piece).
Anti-gas filters (ideal for protection from gas and vapours)
European norm UNI EN 14387:2004 defines various types of filters::
Type A: brown colour filter, for protection from organic vapours with a boiling point of over 65°C.
Type B: grey colour filter, for protection against inorganic gas and vapours (example: chlorine, hydrocyanic acid, hydrogen sulphide).
Type E: yellow colour filter, for protection from acid gases (example: sulphur dioxide, hydrogen chloride).
Tipo K: green colour filter, for protection against ammonia.
Three types of protection classes exist for each type of anti-gas filter. These are differentiated by their capacity, meaning the quantity of contaminant that the filter is able to absorb and therefore the duration (and not efficiency, which is 100%).
Class 1: filter with low capacity and a limit of use equal to 1000 ppm.
Class 2: filter with medium capacity and a limit of use equal to 5000 ppm.
Class 3: filter with high capacity and a limit of use equal to 10000 ppm.
(ppm= parts per million, or rather parts of the contaminant per millions of air parts)