Speech intelligibility while wearing full-facepiece air-purifying respirators

Area of Science:

• Occupational Safety and Health
• Communication Sciences
• Human Factors Engineering

Background:

• Effective communication is vital for law enforcement officers using air-purifying respirators.
• National Institute for Occupational Safety and Health (NIOSH) certification requires a 70% speech intelligibility rating.
• The impact of certified respirators on operational performance is not well-documented.

Purpose of the Study:

• To assess the speech intelligibility of 12 NIOSH-certified air-purifying respirators.
• To predict the impact of these respirators on law enforcement operational performance.

Main Methods:

• Followed NIOSH respirator certification standard testing procedures.
• Applied regression equations from prior studies on speech intelligibility and operational performance.
• Estimated the impact of tested respirators on mission performance and success rates.

Main Results:

• Speech intelligibility ratings ranged from 78% (3M FR-7800B) to 90% (MSA Millennium).
• MSA Millennium and 3M FR-M40 demonstrated statistically significantly higher intelligibility than the 3M FR-7800B.
• All respirators predicted minimal impact on simple mission performance, but complex communication success varied, with some allowing 75% mission completion versus 60% for others.

Conclusions:

• Certified air-purifying respirators exhibit varying levels of speech intelligibility.
• While most respirators have a negligible effect on simple tasks, selection may influence success in complex communication scenarios.
• Further research is needed to fully understand the operational implications of respirator speech intelligibility.