Breathing Zone

By Tabitha Mishra
Last updated: December 13, 2019

What Does Breathing Zone Mean?

The breathing zone is the 10-inch radius immediately surrounding a worker's nose and mouth, where the majority of air is drawn into their lungs.

The breathing zone is monitored during an industrial hygiene survey to aid in determining the presence of airborne contaminants. A personal monitoring device can be attached and worn to monitor the breathing zone for a time period typically lasting anywhere from 30 minutes up to a full shift.

Safeopedia Explains Breathing Zone

Airborne contaminants like dusts, gases, smokes, vapors, and fumes can be controlled through engineering control measures, such as local ventilation and water-based dust suppression systems.

Where engineering controls are not feasible or sufficient, employers are responsible for providing workers with adequate personal protective equipment (PPE), such as respirators. Employers are also required to establish and maintain a respiratory protection program that includes:

  • Employer’s Responsibilities
    • Determining exposure to hazards
    • Fit testing respirators before use
    • Conducting random inspection to ensure respirators are in good condition and effective
  • Employees Responsibilities
    • Checking the fit of the respirator after each donning
    • Using the respirator as per instruction
    • Preventing damage to the equipment (and reporting any signs of wear or tear)
    • If a breach is detected, moving immediately to an area with respirable air

OSHA standard 1910.134 (f)(8)(ii) requires the respirators to be tested for quantitative fit by modifying the facepiece to allow sampling inside the facepiece in the breathing zone of the user. Employers are also required to determine employee exposure measurements from air samples taken from the breathing zone, representing the 8-hour time-weighted average (TWA) and 30-minute short-term exposure for each employee.

Use of Portable Gas Monitors

In addition to respirators, a portable gas detector will help detect any sudden shift in air quality in the breathing zone and alert the user if they need to move to safety.

Gas monitors are important as many toxic gases cannot be detected by smell or sight. To be effective, however, these devices must be worn in the breathing zone, such as the chest pocket, collar or, lapel. OSHA’s definition of a breathing zone is the hemisphere ahead of the shoulders within a radius of six to nine inches, which is the ideal location for these monitors to do their job effectively.


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