Safety at work – why is fit testing so important?
Persons wearing breathing apparatus are often exposed to hazardous pollutants such as chemicals, dust, smoke or gases during their work. Respiratory protection is essential to keep people safe from toxic substances in the area of operation. However, the correct use of facepieces, such as full or half face masks, also plays a key role. Respirators can only provide optimum protection if they are worn correctly and fit tightly. Small leaks, even if imperceptible to the user, can lead to limited protection.
Fit testing, particularly using quantitative measurement methods, is therefore becoming increasingly important. A fit test is used to assess the individual fit of a respirator on the face of the user. Leaks are identified that could allow contaminants to enter the mask.
Fit testing is usually carried out in two ways:
A qualitative fit test uses a test substance such as isoamyl acetate, bitrex or saccharin to detect mask leakage. The respirator user performs various breathing exercises while listening for the taste or smell of the test substance. The presence of the taste or smell indicates that there is a leak that needs to be repaired.
Qualitative measurement methods are often not sufficient to ensure or objectively determine optimal protection.
- Ambient Aerosol Condensation Nuclei Counter (CNC) measures particle concentration inside and outside the mask to assess fit. A special measuring device is used to accurately measure the particle concentration. By comparing the internal and external concentrations, the mask fit (fit factor) can be objectively assessed.
- The other method, Controlled Negative Pressure (CNP), uses a controlled negative pressure to measure leakage at the seal seat of a facepiece.
Why is fit testing important?
- Persons wearing breathing apparatus are often exposed to hazardous pollutants such as chemicals, dust, smoke or gases during their work. Only a tight-fitting mask ensures optimal protection against harmful substances.
- Every face is unique - the fit test allows the mask to be individually assessed and adapted to the face to ensure a personalised fit for maximum safety.
- National and international guidelines, and in some cases legislation, require fit testing as a mandatory measure to ensure the health and safety of workers.
- As well as improving safety, a better fit can also improve comfort for the user.
- Fit tests can contain a key training value for users and equipment managers.
