Using CO(2) to determine inhaled contaminant volumes and blower effectiveness in several types of respirators.

This experiment was conducted to determine how much contaminant could be expected to be inhaled when overbreathing several different types of respirators. These included several tight-fitting and loose-fitting powered air-purifying respirators (PAPRs) and one air-purifying respirator (APR). CO(2) was used as a tracer gas in the ambient air, and several loose-and tight-fitting respirators were tested on the head form of a breathing machine.

Inward leakage in tight-fitting PAPRs.

A combination of local flow measurement techniques and fog flow visualization was used to determine the inward leakage for two tight-fitting powered air-purifying respirators (PAPRs), the 3M Breathe-Easy PAPR and the SE 400 breathing demand PAPR. The PAPRs were mounted on a breathing machine head form, and flows were measured from the blower and into the breathing machine. Both respirators leaked a little at the beginning of inhalation, probably through their exhalation valves.

Testing limits to airflow perturbation device (APD) measurements.

Background: The Airflow Perturbation Device (APD) is a lightweight, portable device that can be used to measure total respiratory resistance as well as inhalation and exhalation resistances. There is a need to determine limits to the accuracy of APD measurements for different conditions likely to occur: leaks around the mouthpiece, use of an oronasal mask, and the addition of resistance in the respiratory system. Also, there is a need for resistance measurements in patients who are ventilated.

Human subject testing of leakage in a loose-fitting PAPR.

Leakage from loose-fitting PAPRs (powered air-purifying respirators) can compromise the safety of wearers. The Martindale Centurion MAX multifunction PAPR is a loose-fitting PAPR that also incorporates head, eye, and ear protection. This respirator is used in mines where coal dust usually is controlled by ventilation systems.

How far can one walk wearing a self-contained self rescuer?

Self-contained self rescuers (SCSRs) are used for emergency escapes in oxygen-deficit atmospheres. Certified by NIOSH to last 1 hour, SCSRs generate oxygen by chemical reaction and must meet a minimum oxygen generation time of 60 min when used according to instructions. Wearers must walk or crawl at a controlled rate to conform to the limits of the devices.

The correlation between personality type and performance time while wearing a respirator.

Many studies have shown that individuals perform better if not wearing a respirator compared with wearing a respirator. This study examined the degree of performance reduction attributable to specific dominant character traits. The subjects performed on a treadmill at a constant speed and grade resulting in 80-85% VO(2)max.

Exercise performance while wearing a tight-fitting powered air purifying respirator with limited flow.

Sixteen subjects exercised at 80-85% of maximal aerobic capacity on a treadmill while wearing a tight-fitting, FRM40-Turbo Powered Air Purifying Respirator (PAPR). The PAPR was powered by a DC power supply to give flow rates of 0%, 30%, 66%, 94%, and 100% of rated maximum blower capacity of 110 L/min. As flow rate was reduced, so was performance time.

Exercise-induced respiratory resistance changes as measured with the airflow perturbation device.

Respiratory resistance (Rrs) changes during physical labor can modify the work of breathing and thus influence the time that the labor can be performed. Ideal in vivo human respiratory performance measurements should have fine temporal resolution and minimally impact the respiratory system itself. The airflow perturbation device (APD) provides respiratory resistance measurements in this manner.