[ RadSafe ] Efficiency of Workers Wearing Respiratory Protection

Dan W McCarn hotgreenchile at gmail.com
Wed Jun 9 18:21:49 CDT 2010

Dear Allen & Ron:

Let me enter into this since I've used several types of PPEs under various
levels of heat and stress.  My answer would simply be, "It Depends". 

It is very important that any person using PPEs of this nature have regular
physicals to determine if they can tolerate the use of a respirator as well
as the more mundane issues of respiratory training and fitting. It is also
very important to monitor the vitals of any individuals involved in a work
activity in elevated temperatures.

The list of dependencies include: temperature, humidity, age, general health
& physical condition, heat tolerance, tolerance to physical stress, lung
capacity & pulmonary performance, altitude, type of respirator, resistance
to air flow, nature of regulator (demand or positive pressure) on
air-supplied respirator, etc. If the personnel are also wearing protective
clothing (Level A, B or C), then the heat / respiratory stress can become
overwhelming very rapidly.


I once watched a company of Austrian troops put on chemical-resistant suits
& respirators on a pleasantly warm summer's day.  Before they were able to
complete getting the equipment on, all became very hot but 15 developed heat
stress so badly that the exercise was cancelled. One developed severe heat
stroke and was hospitalized briefly.  Remember that these were healthy, fit
young men.  The heat stress took only minutes to develop.

SCBA, used in positive pressure mode can significantly reduce heat stress.
However, the same equipment switched to demand regulator mode in the same
conditions can rapidly create an enormous amount of stress (from personal
experience) resulting in injury and perhaps even death.  Core temperatures
can rise very quickly under this type of heat stress.

I believe that the ambient temperature followed by humidity and level of
physical work are the most critical factors, from personal experience. OSHA
40-hour training emphasizes the planning of work with respirators / PPEs in
the coolest possible conditions, e.g. night, if the ambient day temperatures
are warm.  Cold packs & their ilk used in undergarments can also
significantly reduce heat stress.

A rule of thumb... Let the individuals choose the level of stress that they
can safely tolerate, but monitor their temperature, pulse & respiratory
rates so that there is a sufficient safety factor. The level of tolerable
work will vary strongly according to ambient temperature.

Have available plenty of cold fluids, something to replace electrolytes
(Gatorade) preferably not caffeinated and allow frequent breaks.  If you are
concerned about heat stress, perhaps planning the work at night might help.
You remember the scorcher that we had last Saturday in Los Alamos... that
would not be a day to ask anyone to use a respirator.


Dan ii
Dan W McCarn, Geologist
108 Sherwood Drive
Los Alamos, NM 87544-3425
+1-505-310-3922 (Mobile - New Mexico) 
+1-505-672-2014 (Home - New Mexico)
HotGreenChile at gmail.com (Private email) HotGreenChile at gmail dot com

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu
[mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Treadaway, Walter
Sent: Wednesday, June 09, 2010 15:04
To: radsafe at health.phys.iit.edu
Subject: [ RadSafe ] Efficiency of Workers Wearing Respiratory Protection

It seems logical to assume that a worker doing a job wearing respiratory
protection would be slower than the same worker without respiratory
protection.  However, I can't find a reference in a peer-reviewed
publication to support this assumption.
Does anyone have a reference "in their back pocket" or can anyone point me
in the right direction?


Allen Treadaway for Ron Morgan, LANL
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