TWO TYPES OF BREATHING PROTECTION

1. FILTER PROTECTION

Where the surrounding air passes through filters that remove contaminants. This type is used where sufficient oxygen level is present and known conta­minants can be captured in the filter. The contaminants must have clear warning properties in the form of odours or taste in concentrations below the occupational exposure limits. Filters must not be used where the contaminant concentrations are Immediately Dangerous to Life and Health.

Examples of filter protection are half and full face masks with replaceable filters as well as powered-assisted filter protection for half and full masks or hoods, visors and helmets. For conta­minants in gas form, appropriate gas filters are used with active carbon that absorbs the gas. As the filter becomes saturated the gradual break­through starts, therefore it is important to set up a filter replacement policy.

Particles such as dust, smoke and mist are captured in particle filters. As the degree of clogging rises, breathing resistance increases and the filter must be replaced if it is damaged or breathing becomes difficult. Combination filters are used in the presence of both particles and gas.

2. BREATHING APPARATUS

Supplies the user with air from an independent source, via cylinders with compressed air or breath­able air from a compressor. Continuous flow air line equipment with hoses is used in half and full face masks, hoods, helmets and visors.

Compressed air-fed breathing protection may be used in all environments suitable for filters and in which a higher level of protection is required. Some substances can not be adsorbed in filters, and in such cases compressed air-fed breathing protection is the only alternative.

The inhaled air must conform to EN 12021 and as an example not exceed the odour threshold for oil (0.5 mg/m³).

WORK DURATION AND WORKLOAD

For short term jobs with low workload, a negative pressure mask can be used, i.e. half and full face masks with replaceable filters. To avoid harmful leakage into the mask, the fit to the face is important, as inhaling produces a negative pressure in the mask. High inhalation resistance due to large filter combinations contributes to further negative pressure as well as an increased breathing effort.

Long term work with high workloads often requires powered-assisted filter protection. A battery driven fan sucks the air through the filter and blows it into the face piece, which may be a loose-fitting visor, helmet or hood, or a tight fitting half or full face mask. The air flow of the equipment is important to maintain a positive pressure in the face piece, even during deep inhalation, especially with the use of loose fitting visors, helmets or hoods.

High workloads and contaminants with poor warning properties are examples of situations in which compressed air line equipment is appropiate. The com­pressed air is supplied from a compressor via an air line filter unit and hose to a belt-mounted regulating valve, to the half or full face mask or helmet, visor or hood.

PROTECTION FACTOR

All types of breathing protection have a specific protection factor that describes how efficiently they reduce the level of the contaminant in the air, i.e. inside the face piece.

The Assigned Protection Factor (APF)
is based on measurements inside and outside the ­pro­tective device, conducted on workers in real work environments.

The Nominal Protection factor (NPF)
is based on laboratory measurements in conjunction with approval of the protection equipment to the EN standard.

Calculation of the protection needed at the workplace should be based on the Assigned Protection Factor (APF). Check national requirements for assigned protection factors EN 529.

FACE FIT TESTING

To maximise on the correct protection from respiratory equipment, it is crucial to ensure that it fits the user to an optimum level. Air will always take the path of least resistance, so any small gaps between the face and the respirator will result in reduced protection for the wearer. It is crucial to their safety that the user has a suitably sized and positioned respirator, which they know how to correctly fit.

Why undertake a Face Fit Test (FFT)?
Sundstrom recommends that any half or full-face mask user undergoes a Face Fit Test. Such a test ensures the correct comfort, fit and protection obtained whilst the user is wearing a face mask. One size does not fit all, and the mask must have a suitable and effective fit for you!

Facial hair and jewellery, scars or outstanding facial features can all significantly detract from the performance of a respirator. In order to ensure that there is not leakage between the face and the respirator, leading to potential health issues, the face fit test is used to ensure an adequate seal has been achieved.

Exposure to even low levels of particles, gases and vapours can cause permanent and irreversible damage to the lungs and other vital organs. The importance of correctly protecting against these contaminants over an entire working career has become more apparent. A face fit test ensures that the RPE is both fit for purpose and acceptable to the wearer. In some markets it is a legal requirement, whilst in others it is only a guidance.

Carefully check the regulation that applies to you!

Fit Test Methods
There are two approved test types which can verify the fit of a face mask.

Qualitative fit test
As the name suggest this type of Face Fit Test is objective. It involves placing a bag over the head of the wearer whilst wearing the respirator. A substance with a strong smell or taste (normally either Bittrex, giving a bitter taste, Saccharin, giving a sweet taste or banana oil with a strong banana smell) is added into the bag. If the wearer cannot smell or taste any of the additives, they are seen to have an adequate seal. This methodology can be compromised if the wearer has animpaired sense of smell or taste, a cold, or other sensory issue. It is also only suitable for use with half masks!

Quantitative fit test
This is a much more accurate and sensitive test giving a defi- nitive number of particles inside the mask whilst undertaking several exercises. It also measures the particle count outside the mask and calculates a specified ratio between the two.

By comparing both figures you can obtain the measurable level of protection given by the mask. There are a number of ways of performing the quantitative test but all show a more tangible and effective conclusion, offering greater confidence in use.

This type of test can be used on both half masks and full-face masks.

Qualitative adaptation test
In qualitative adaptation tests, the user is exposed to a substance that either tastes or smells strongly.

In qualitative adaptation tests, the user is exposed to a substance that either tastes or smells strongly.

Usually you use Bitrex, which has a bitter taste, or Saccharin, which has a sweet taste. You can also use isoamyl acetate (banana oil) which smells like banana.

The problem with this type of adaptation test is that it is objective where the user has to say whether they smell or taste. If people have a cold or have a reduced sense of smell or taste, this may mean that the respiratory protection does not work. This method is only applied to half masks.

Quantitative fit test
Sundström Safety recommends using quantitative fit tests where you measure the number of particles inside and outside the mask and thus obtain a fit factor.

This applies especially to exposure to carcinogenic or allergenic substances. There are a number of different ways to perform these quantitative tests and it is either with well-tested test methods or in a laboratory environment with so-called Total Leakage Tests.

This type of fit test can be used for both half masks and full masks.