Issues to consider when selecting a respirator

The basis for selection and performance of respirators in Australia is normally based on OH&S legislation, regulations and on the relevant Australian Standards:

AS/NZS1716 "Respiratory protective devices" - this is the performance standard. It sets out the performance parameters and requirements for the different types of respirators

AS/NZS1715 "Selection, use and maintenance of respiratory protective devices" provides users with the information they need to select and use appropriate respiratory protection systems.

There are other regulations and codes of practice that specify the appropriate respiratory protection for specific applications e.g. for use when removing asbestos and when spraying paints containing isocyanates.

After identifying the type and level of the respiratory hazards, suitable respiratory equipment for these conditions can be identified. Normally there will be a number of options, depending on the local conditions, wear time, cost and other factors.

Filter Classifications

Under AS/NZS1716, filters in respirators are required to meet certain performance levels - this then allows determination of its suitability for use against specific contaminants at various concentrations as explained in AS/NZS1715.

Seek the advice of an occupational hygienist or safety professional to determine the correct options. There are two main types of filters:

Particle filters

Filters are tested for capture efficiency using a salt aerosol challenge agent. Under specified test conditions, the amount of these particles that break through the filter is measured which allows classification of the filter.

Under the Standard, there are three classes of particle filters:

• P1 - for mechanically generated particles eg dusts, flour, silica. Suitable for the relatively “large” particles (mostly >1 micron) released in operations like sanding, cutting, sawing, crushing etc.
• P2 – for mechanically & thermally generated particles eg welding fume. These filters have a higher efficiency to deal effectively with smaller, thermally generated particles like welding fume and is also recommended for infection control applications e.g. TB, flu or other infectious diseases.
• P3 – for use with highly toxic materials and/or when a very high protection level is required e.g. beryllium, radioactive particles.

Gas and Vapour Filters

Gas/Vapour filters are produced specifically for use against various gases and vapours and are tested and marked accordingly. There are many different types – some common ones are:

TYPE        Target Contaminants
A               Organic vapours with boiling points > 650C
B               Acid Gases eg chlorine, hydrogen sulphide
E               Sulphur Dioxide
G               Low vapour pressure materials–eg agricultural chemicals (pesticides, herbicides etc)
K               Ammonia
Hg            Mercury

All gas/vapour filters are also rated for their absorptive capacity. In increasing capacity there are Class Aus, Class 1, Class 2 and Class 3 filters. Therefore, for example, you can get an A1 filter or a B(Aus) or a multi-class A2B1. The higher the class, the higher and longer the concentration they are able to deal with when fitted on the right type of respirator.

By combining the two types of filters, we can get combination filters like A1P2, BAusP1 or A1B1E1K1P3.

For the employer or worker who is not familiar with the various factors and product features necessary to in choose the correct respiratory protection, 3M Australia operates a TechAssist Helpline (1800 024 464) that is available to purchasers/users of 3M products.

Advice and guidance will be given to assist in providing the end user with the information needed to obtain appropriate respiratory protection for the task at hand.