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

Johnson AT, Koh FC, Scott WH, Rehak TE - J Environ Public Health (2011)

Bottom Line: Wearer protection factors were found to range from 1.1 for the Racal AirMate loose-fitting PAPR to infinity for the 3M Hood, 3M Breath-Easy PAPR, and SE 400 breath-responsive PAPR.Blower effectiveness was about 1.0 for tight-fitting APRs, 0.18 for the Racal, and greater than 1.0 for two of the loose-fitting PAPRs.With blower effectiveness greater than 1.0, some blower flow during the exhalation phase contributes to the subsequent inhalation.

View Article: PubMed Central - PubMed

Affiliation: Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA. artjohns@umd.edu

ABSTRACT
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. CO(2) concentration in the exhaled breath was monitored as well as CO(2) concentration in the ambient air. This concentration ratio was able to give a measurement of protection factor, not for the respirator necessarily, but for the wearer. Flow rates in the filter/blower inlet and breathing machine outlet were also monitored, so blower effectiveness (defined as the blower contribution to inhaled air) could also be determined. Wearer protection factors were found to range from 1.1 for the Racal AirMate loose-fitting PAPR to infinity for the 3M Hood, 3M Breath-Easy PAPR, and SE 400 breath-responsive PAPR. Inhaled contaminant volumes depended on tidal volume but ranged from 2.02  L to 0  L for the same respirators, respectively. Blower effectiveness was about 1.0 for tight-fitting APRs, 0.18 for the Racal, and greater than 1.0 for two of the loose-fitting PAPRs. With blower effectiveness greater than 1.0, some blower flow during the exhalation phase contributes to the subsequent inhalation. Results from this experiment point to different ways to measure respirator efficacy.

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Related in: MedlinePlus

Flows and volumes for the SE 400 breath-responsive PAPR. Blower flow rate was adjusted to maintain positive pressure inside the face piece. Corresponding contaminant volumes (below) were negligible.
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Related In: Results  -  Collection


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fig4: Flows and volumes for the SE 400 breath-responsive PAPR. Blower flow rate was adjusted to maintain positive pressure inside the face piece. Corresponding contaminant volumes (below) were negligible.

Mentions: Figure 4 illustrates responses by the SE 400 breath-responsive tight-fitting PAPR. Blower flow rate tracks breathing machine flow rate in an attempt to maintain positive pressure inside the facepiece. Again, inhaled volume of contaminants is zero.


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

Johnson AT, Koh FC, Scott WH, Rehak TE - J Environ Public Health (2011)

Flows and volumes for the SE 400 breath-responsive PAPR. Blower flow rate was adjusted to maintain positive pressure inside the face piece. Corresponding contaminant volumes (below) were negligible.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3139880&req=5

fig4: Flows and volumes for the SE 400 breath-responsive PAPR. Blower flow rate was adjusted to maintain positive pressure inside the face piece. Corresponding contaminant volumes (below) were negligible.
Mentions: Figure 4 illustrates responses by the SE 400 breath-responsive tight-fitting PAPR. Blower flow rate tracks breathing machine flow rate in an attempt to maintain positive pressure inside the facepiece. Again, inhaled volume of contaminants is zero.

Bottom Line: Wearer protection factors were found to range from 1.1 for the Racal AirMate loose-fitting PAPR to infinity for the 3M Hood, 3M Breath-Easy PAPR, and SE 400 breath-responsive PAPR.Blower effectiveness was about 1.0 for tight-fitting APRs, 0.18 for the Racal, and greater than 1.0 for two of the loose-fitting PAPRs.With blower effectiveness greater than 1.0, some blower flow during the exhalation phase contributes to the subsequent inhalation.

View Article: PubMed Central - PubMed

Affiliation: Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA. artjohns@umd.edu

ABSTRACT
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. CO(2) concentration in the exhaled breath was monitored as well as CO(2) concentration in the ambient air. This concentration ratio was able to give a measurement of protection factor, not for the respirator necessarily, but for the wearer. Flow rates in the filter/blower inlet and breathing machine outlet were also monitored, so blower effectiveness (defined as the blower contribution to inhaled air) could also be determined. Wearer protection factors were found to range from 1.1 for the Racal AirMate loose-fitting PAPR to infinity for the 3M Hood, 3M Breath-Easy PAPR, and SE 400 breath-responsive PAPR. Inhaled contaminant volumes depended on tidal volume but ranged from 2.02  L to 0  L for the same respirators, respectively. Blower effectiveness was about 1.0 for tight-fitting APRs, 0.18 for the Racal, and greater than 1.0 for two of the loose-fitting PAPRs. With blower effectiveness greater than 1.0, some blower flow during the exhalation phase contributes to the subsequent inhalation. Results from this experiment point to different ways to measure respirator efficacy.

Show MeSH
Related in: MedlinePlus