Fluke 985 Application Note 2412973

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In the highly sensitive environment of a healthcare facility,

where both infectious patients and those highly susceptible

to infection receive treatment, it is essential to minimize the

possibility of infection and disease transmission.

From the Fluke Digital Library @ www.fluke.com/library

Airborne particle counters

provide vital information for

maintaining indoor air quality

in healthcare facilities

One potential vector of infection

that must be managed is the air

circulating within the building.

Failure to correctly monitor and

manage indoor air quality can

add cost due to increased lengths

of stay, expose the institution to

liability and, more importantly,

expose patients and staff to

unnecessary risk.

In an effective indoor air qual-

ity (IAQ) program, a handheld

airborne particle counter such as

the Fluke 983 is an important

tool. Used in conjunction with

pressure and airflow testers, par-

ticle traps and laboratory

analysis, the particle counter can

provide facilities managers with

the data they need to detect IAQ

problems, identify and address

root causes and verify when con-

ditions have returned to

acceptable levels.

Specifically, a particle counter

enables the healthcare facility

manager to:

•Document baseline particle

counts within a specific space

•Detect when airborne particu-

late levels diverge from

baseline or “normal” levels

•Gain early warning of underly-

ing issues, such as changes

in operating procedures,

equipment malfunctions,

maintenance shortcomings or

failure to separate construction

zones from patient areas

•Test particle levels after

changes have been made, to

ensure that remedies have

been effective

The use of handheld test instru-

ments has received endorsement

at the highest levels. According

to infection control guidelines

published by the U.S. Centers for

Disease Control in 2003, “the use

of handheld, calibrated equipment

that can provide a numerical

reading on a daily basis is pre-

ferred for engineering purposes”

in ensuring the proper and safe

operation of HVAC systems.i

It must be clearly stated, how-

ever, that the particle counter is

not designed to determine what

particles consist of or whether

the particles counted pose a

threat of infection. Those judg-

ments must be based on

laboratory analysis of particle

samples collected in the health-

care facility and cultured in a

laboratory setting.

Technology

at Work

2 Fluke Corporation Airborne particle counters provide vital information for maintaining indoor air quality in healthcare facilities

The spread of infection through the indoor air is a serious

potential problem in healthcare facilities. Such infections

can stem from two sources:

• Infectious agents produced by people inside the facility,

such as Tuberculosis, Rubella (measles) and influenza

• Agents normally present in the human environment that

can endanger patients who have compromised

immune systems. Such organisms include Aspergillus

fumigatus, a common species of mold, and others.

Other airborne particulates, such

as inorganic materials and aller-

gens, while capable of causing

health problems, pose a lesser

threat to patients. These contami-

nants will not be addressed in

this document, though the air fil-

tration and air pressure balancing

techniques that help control bio-

logical pathogens can also control

odors, dust and other non-viable

air pollutants.

To control the movement and

spread of infectious agents, facil-

ity designers and managers

establish special purpose spaces

called Airborne Infection Isolation

(AII) or patient isolation room,

and Protective Environment (PE)

facilities. In both of these special

ventilation spaces, air pressures

are regulated to move air from

clean to dirty areas.

The AII room would house a

patient judged to be a source of

airborne infection, such as

Mycobacterium tuberculosis or

measles virus. Vents draw air

from the room and exhaust it out-

side the building. High efficiency

particulate air (HEPA) filters may

be used to help remove particles

from the air. Makeup air flowing

into the room is balanced so that

the room remains under negative

air pressure. Thus the direction of

airflow under the door or when

the door is opened is into the

space, rather than out, helping

contain infectious particles.

The Protective Environment

facility is designed to keep infec-

tious agents out and protect

immuno-suppressed patients and

others, such as bone-marrow and

organ-transplant patients and

premature infants, who are espe-

cially vulnerable to opportunistic

infectious agents. The CDCii rec-

ommends that PE facilities be

maintained under positive air

pressure, with directional airflow

(from one side of the room, across

the patient to the exhaust) and

twelve or more air changes per

hour. Clean air is supplied

through HEPA filters, and point-

of-use HEPA filters may also be

used. Air flowing through an

open door or leak moves out of

the space, not in.

Sources of IAQ Problems in Healthcare Facilities

3 Fluke Corporation Airborne particle counters provide vital information for maintaining indoor air quality in healthcare facilities

AII and PE facilities provide a framework for limiting the

spread of infectious agents, but they are not foolproof.

Building design, inconsistent or inadequate operating

procedures, poor maintenance and facilities construction

and renovation projects all have the potential to cause

problems. And in any case, protective facilities are not

used for all patients.

Even the best air filtration and

airflow design can be defeated

by inadequate maintenance or

incorrect operation. A slipping

fan belt on a ventilation supply

fan, for instance, could alter

the air balance in a protective

environment facility, allowing

particle-laden air from the hall-

way outside to flow in. Failure to

correctly seal off and ventilate a

construction area can send a

cloud of construction dust and

Aspergillus spores into areas

where patients are housed.

Failure to fix a leaking sink can

turn the cabinet below into a

nursery for potentially hazardous

mold.

Andrew Streifel, MPH, hospital

environment specialist at the

University of Minnesota, recalls

what happened when cost-

conscious hospital administrators

turned off the fan ventilating the

space over a dropped ceiling in

an intensive care area. “That

allowed humidity to stagnate,” he

says. “When humidity reached

extremely high levels in the

Minnesota summer, it started

raining in the ICU. The water

was coming through the ceiling

grid and dripping on the patients.

They stopped using four or five of

the intensive care rooms, and

diverted patients.” The larger

concern, Streifel continues, was

the possibility that the high

humidity would permit mold

growth. Raising the room

temperature above the dewpoint

provided a temporary fix, and

stopped the “rain.”iii

Building construction and

renovation can pose particular

challenges. Disruption to the

building’s envelope, generation

of large amounts of construction

dust and debris and the move-

ment of workers and equipment

in and out of containment zones

all present contamination threats

beyond the norm for a healthcare

Sources of IAQ Problems

facility. According to the CDC, “a

recent aspergillosis outbreak

among oncology patients was

attributed to depressurization of

the building housing the HSCT

unit while construction was

underway in an adjacent build-

ing. Unfiltered outdoor air flowed

into the building through doors

and windows, exposing patients

in the HSCT unit to fungal spores.

iv

When such problems occur, an airborne particle counter

such as the Fluke 983 can help hospital staff and industrial

hygienists detect increased particle levels, identify the

sources and verify the effectiveness of remedial action.

The Fluke 983 Particle Counter

operates by pumping an air sam-

ple of known volume—generally

one liter—past a laser beam. As

dust particles in the air stream

pass through the beam, each one

reflects or “scatters” the laser

light. A photodetector senses the

scattered light and generates an

analog electrical signal. Larger

particles scatter more light and

create higher-voltage electronic

“hits.” Onboard electronics track

the hits and count the particles in

six size categories, ranging from

.3 microns to 10 microns.

Particles larger than 10 microns

generally settle out of the air.

The Fluke 983 can be pro-

grammed to take repeat counts

instantly, or delayed up to 24

hours between samples. It can

store 5000 records of date, time,

counts, relative humidity, temper-

ature, sample volumes, alarms

and location label records in its

onboard memory. Stored readings

may then be downloaded to a

personal computer. As an alterna-

tive, the particle counter can be

connected directly to a PC for real

time downloads.

According to the CDC,

“Particulate sampling (i.e., total

numbers and size range of partic-

ulates) is a practical method for

evaluating the infection-control

performance of the HVAC system,

with an emphasis on filter effi-

ciency in removing respirable

particles (< 5 µm in diameter) or

larger particles from the air.”v

The accuracy, speed and

compact size of the Fluke 983

make it useful for baseline partic-

ulate testing, problem detection

and remediation and system

maintenance.

•Baseline Testing. To know

when the “abnormal” occurs,

it’s necessary to document

what are normal levels of par-

ticles. According to Andrew

Streifel, it’s not reasonable to

expect “clean room” conditions

in a healthcare setting. When

staff rush into a room to inter-

vene in a patient emergency,

there’s no time to worry about

air quality. Particle counts will

soar with the presence of mul-

tiple people (human beings

shed some 500,000 particles

each minute) and medical pro-

cedures too can contaminate

the air. But later, counts should

return to normal or baseline

levels. Best practice calls for

baseline particulate levels to

be documented, both within

spaces and in the supply air

flowing into the space.

•Maintenance Testing. Once

baseline or “normal” particle

levels are determined,

followup tests should be

performed and documented

periodically. These followup

tests can provide early warn-

ing of developing anomalies

and enable the facility

manager to intervene before

anyone gets sick.

•Filter Testing. Used to test for

particle levels in the air

upstream and downstream

from filter media, the Fluke

983 can verify that filters are

performing as they should.

Testing the level of particles

in incoming filtered air at the

diffuser (air grate)—air that

should be the cleanest in the

room—provides an additional

check on the performance of

filtration systems.

Contamination Testing with Airborne Particle Counters

4 Fluke Corporation Airborne particle counters provide vital information for maintaining indoor air quality in healthcare facilities

Writing in HPAC Engineering

magazine, Streifel said “when

dealing with filtration testing,

the verification data should

be reflected with objective

analysis by providing

airborne-particle comparison

with the specifications of filter

efficiency for fan systems. The

objective analysis available

today should provide function-

ing pressure gauges,

inspection information of the

filter banks, and objective

particle analysis of filters for

filtration leaks. The particle-

analysis procedures at this

time are not standardized but

yet the comparison of before

versus after filter tests with

atmospheric dust particle

sizing will help to assure that

the 90-percent-efficient filter

is removing 90 percent of the

particles greater than 0.5 µm.”vi

•Locating Particle Sources.

The Fluke 983 can help

identify areas where particle

counts are elevated and,

ultimately, lead the user to

the source. A leaking air duct

could be sending unfiltered

air into a room, for instance;

work above a suspended

ceiling could be disturbing

accumulated dust.

•Verifying the Effectiveness

of Remediation.Once the

causes of higher particle

counts have been addressed,

post-testing will show

whether the fixes employed

have really worked at bringing

particulate levels down.

Controlling airborne contamina-

tion within healthcare facilities

poses a complex set of challenges

far beyond the scope of this

paper. Numerous additional

resources are available to help

the professional understand and

overcome those challenges.

Among those easiest to grasp is

the Fluke 983 handheld airborne

particle counter.

Fluke Corporation

PO Box 9090, Everett, WA USA 98206

Fluke Europe B.V.

PO Box 1186, 5602 BD

Eindhoven, The Netherlands

For more information call:

In the U.S.A. (800) 443-5853 or Fax (425) 446-5116

In Europe/M-East/Africa (31 40) 2 675 200 or

Fax (31 40) 2 675 222

In Canada (800) 36-FLUKE or Fax (905) 890-6866

From other countries +1 (425) 446-5500 or

Fax +1 (425) 446-5116

Web access: http://www.fluke.com

©2005 Fluke Corporation. All rights reserved.

Printed in U.S.A. 5/2005 2461172 A-US-N Rev A

Fluke. Keeping your world

up and running.

5 Fluke Corporation Airborne particle counters provide vital information for maintaining indoor air quality in healthcare facilities

i Guidelines for Environmental Infection Control in Health-Care

Facilities, Recommendations of CDC and the Healthcare Infection

Control Practices Advisory Committee (HICPAC), U.S. Department of

Health and Human Services Centers for Disease Control and

Prevention (CDC), 2003, page 20.

ii Ibid, page 34

iii Interview with Andrew Streifel, April 22, 2005

iv Ibid, page 26

v Ibid, page 27

vi “Hospital Accreditation for Airborne Infection Control,” by Andrew

J. Streifel, MPH, HPAC Enginering, March 2003, page 49.