Monthly Archives: April 2015

Choosing a dust mask

Choosing a dust mask

We often have questions regarding which mask should be used and so thought a very quick summary here would be useful.APF graphic

In general, filtering face masks used for dusts and similar can be categorised into three types all with an FFP number.

  • FFP1 for simple dusts such as nuisance and soft wood dusts
  • FFP2 for more hazardous dusts such as grinding, powder painting or respirable cystalline silica
  • FFP3 for hazardous dusts which also involve some vapours and gases which are hazardous to health (a good example here would be welding fumes)

One of the key failing when we review the use of face masks is how people wear them and you should, since November 2002 in fact, be testing the fit of these items to ensure they are effective – this is known as fit testing.

Many people do not fit masks well and do not even press the metal strip fixed around the nose of the mask to get a good seal – if a mask is to protect you this is essential.  A second common error is keeping the mask at the point of work uncovered – perhaps on a work bench.  This will allow the mask to collect exactly what it should be protecting you from and allow you to inhale it as soon as you use it!  Always keep RPE in a sealed container or bag to prevent this type of contamination.

More information is supplied below on the new APF figures.  These allow you, once occupational hygienists, such as ourselves, have completed an appropriate air sampling survey, to select an item of RPE which will adequately protect you and your staff from harm (see graphic to the right for more information). The APF is an allowance over which the mask will protect you;

For example; the allowable limit for hard and soft wood dusts is currently 5 mg per cubic metre.  In your workplace an occupational hygienist such as one of our safety consultants may measure the dust level at 3 times this amount, 15 mg per m3.  In that case you would need to seek an APF (assigned protection factor) of at least 3.  This would put you in the typical 4-10 or 4-20 range.

One final point concerns the amount of time which a mask will last before requiring replacement, this can be summarised as follows;

  • For particulate (dusts) when breathing become more difficult the mask will be partially blocked and should be replaced
  • For gases and vapours the mask should be replaced when you detect ‘breakthrough’ i.e. when you can detect through smell or taste the item against which you should be protected be that a solvent or other substance.

As a general rule, disposable masks should be disposed of daily and reusable half face respirators should have their filters changed at least monthly.

If you would like to speak to an experienced occupational hygienist about this please contact us on 01453 800100

Posted by Roger Hart
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