Cornell University Ergonomics Web - Professor Alan Hedge · 2020. 1. 14. · Presentation at 3M...

Presentation at 3M Symposium on Office Ergonomics, November 15, 2000 ©Prof. Alan Hedge

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© Alan Hedge 11/00

Workplace Design and Workplace Design and Workplace Design and Workplace Design and Glare ReductionGlare ReductionGlare ReductionGlare Reduction

Professor Alan HedgeDept. Design & Environmental Analysis,

Cornell University, Ithaca, NY 14853, USA.

Slide 2

© Alan Hedge 11/00

Indoor Environmental QualityIndoor Environmental QualityIndoor Environmental QualityIndoor Environmental Quality

LightingLightingIndoor Air QualityIndoor Air Quality

Workstation design Workstation design

Slide 3

© Alan Hedge 11/00

Workstation Design: Workstation Design: Workstation Design: Workstation Design: Deviated Work PostureDeviated Work PostureDeviated Work PostureDeviated Work Posture

Knee compression

Knee compression

Flexed neckFlexed neck

Unsupported,kyphotic backUnsupported,kyphotic back

Ankle compression

Ankle compression

Abducted arms

Abducted arms

Extended wrists

Extended wrists

Inappropriate viewing

distance and monitor height

Inappropriate viewing

distance and monitor height


Slide 4

© Alan Hedge 11/00

Keyboard on DeskKeyboard on DeskKeyboard on DeskKeyboard on Desk

Unsuitable for sustained keyboard work:

70° acute elbow angle will increase upper limb fatigue

and nerve compression.(after Stack, 1987)

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© Alan Hedge 11/00

Keyboard on Lowered TrayKeyboard on Lowered TrayKeyboard on Lowered TrayKeyboard on Lowered Tray

Unsuitable for sustained keyboard work:

Fingers cannot rest on keys ~90° elbow

angle

Wrist extension

(after Stack, 1987)

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© Alan Hedge 11/00

Keyboard on Negative Slope TrayKeyboard on Negative Slope TrayKeyboard on Negative Slope TrayKeyboard on Negative Slope Tray

Ideal for sustained keyboard work:

Fingers can rest on keys >90° elbow

angle

Wrist neutral

(after Stack, 1987)


Slide 7

© Alan Hedge 11/00

Cornell/Honeywell StudyCornell/Honeywell StudyCornell/Honeywell StudyCornell/Honeywell Study(Hedge (Hedge (Hedge (Hedge et alet alet alet al., ., ., ., ErgonomicsErgonomicsErgonomicsErgonomics, 1999), 1999), 1999), 1999)

Desk group

Tray group

Tiltdown groupBefore and after study of keyboard systems.

Keyboard tray slope 10°

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© Alan Hedge 11/00

Cornell/Honeywell StudyCornell/Honeywell StudyCornell/Honeywell StudyCornell/Honeywell StudyControl Group Wrist Extension

Slide 9

© Alan Hedge 11/00

Cornell/Honeywell StudyCornell/Honeywell StudyCornell/Honeywell StudyCornell/Honeywell StudyTest Group Wrist Extension


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© Alan Hedge 11/00

Cornell/Honeywell StudyCornell/Honeywell StudyCornell/Honeywell StudyCornell/Honeywell Study(Hedge (Hedge (Hedge (Hedge et alet alet alet al., 1999)., 1999)., 1999)., 1999)

Conventional Tray

Ulnar Radial

Extension

Flexion

Tiltdown system

Ulnar RadialFlexion

Extension

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© Alan Hedge 11/00

<25%25-50%

>50%

Control groupSurvey 1 Survey 2 Survey 1 Survey 2

PT Test group

Cornell/Honeywell Study: Cornell/Honeywell Study: Cornell/Honeywell Study: Cornell/Honeywell Study: Reported discomfortReported discomfortReported discomfortReported discomfort

(Hedge (Hedge (Hedge (Hedge et alet alet alet al., Ergonomics 1999)., Ergonomics 1999)., Ergonomics 1999)., Ergonomics 1999)

Slide 12

© Alan Hedge 11/00

Keyboard Slope and Wrist ExtensionKeyboard Slope and Wrist ExtensionKeyboard Slope and Wrist ExtensionKeyboard Slope and Wrist Extension((((SimoneauSimoneauSimoneauSimoneau et alet alet alet al., 1999)., 1999)., 1999)., 1999)

• 10 female Ss typed on keyboard at different slope angles.

• Wrist extension decreased 1° for every 2° decrease in keyboard angle.

• Optimal wrist position was when the keyboard tilted down in a range between 7-15°.


Slide 13

© Alan Hedge 11/00

Keyboard PositionKeyboard PositionKeyboard PositionKeyboard Position

• Lowered, negative-tilt tray for neutral wrist posture.

Slide 14

© Alan Hedge 11/00

Encourage Neutral PostureEncourage Neutral PostureEncourage Neutral PostureEncourage Neutral Posture

Relaxed, balanced

neck

Relaxed, supportedshoulders

Supported, lordoticback

Open elbow

Neutral wrist,

supported palm

Preferred viewing angle,

distance and

monitor height

Open knees,ankles

Slide 15

© Alan Hedge 11/00

Indoor Air Quality ProblemsIndoor Air Quality ProblemsIndoor Air Quality ProblemsIndoor Air Quality Problems

• 1 in 3 workers may be in a "sick"building.


Slide 16

© Alan Hedge 11/00

Office Indoor Air Quality Office Indoor Air Quality Office Indoor Air Quality Office Indoor Air Quality ConcernsConcernsConcernsConcerns

Combustion gases(COx, NOx, SOx)

Combustion gases(COx, NOx, SOx)

Volatile organics(VOCs, MVOCs)

Volatile organics(VOCs, MVOCs)

Particulates/ fibers(ETS, SMF, Asbestos)

Particulates/ fibers(ETS, SMF, Asbestos)

Biogenic particles(bacteria, fungal

spores,allergens)

Biogenic particles(bacteria, fungal

spores,allergens)

Thermal conditionsThermal conditions

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Breathing Zone FiltrationBreathing Zone FiltrationBreathing Zone FiltrationBreathing Zone Filtration• Energy efficiency - not all office air needs to be treated, only

that in the breathing zone. • Thermal comfort - eliminating 'dead zones' improves thermal

comfort conditions.• Personal control - most HVAC systems have only crude control

mechanisms.

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© Alan Hedge 11/00

Cornell Study:Cornell Study:Cornell Study:Cornell Study:Statistics CanadaStatistics CanadaStatistics CanadaStatistics Canada

(Hedge (Hedge (Hedge (Hedge et alet alet alet al., ., ., ., Indoor AirIndoor AirIndoor AirIndoor Air, 1993), 1993), 1993), 1993)


Slide 19

© Alan Hedge 11/00

Statistics CanadaStatistics CanadaStatistics CanadaStatistics Canada(Hedge (Hedge (Hedge (Hedge et alet alet alet al., ., ., ., Indoor AirIndoor AirIndoor AirIndoor Air, 1993), 1993), 1993), 1993)

Control floor

BZF Test floor

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© Alan Hedge 11/00

BZF and BZF and BZF and BZF and VOCsVOCsVOCsVOCs(Hedge (Hedge (Hedge (Hedge et alet alet alet al., ., ., ., Indoor AirIndoor AirIndoor AirIndoor Air, 1993), 1993), 1993), 1993)

0

0 .5

1

1 .5

2

2 .5

pre-control

post-control

pre-BZF post-BZF

ppm

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© Alan Hedge 11/00

BZF and Airborne ParticulatesBZF and Airborne ParticulatesBZF and Airborne ParticulatesBZF and Airborne Particulates(Hedge (Hedge (Hedge (Hedge et alet alet alet al., ., ., ., Indoor AirIndoor AirIndoor AirIndoor Air, 1993), 1993), 1993), 1993)

P re -po st c ha n ge in p a rtic u late lev els

(< .25 µµµµ m )

52

3 6

0

20

40

60

Control BZF

count/cc


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© Alan Hedge 11/00

BZF and Perceived Environment BZF and Perceived Environment BZF and Perceived Environment BZF and Perceived Environment Conditions Conditions Conditions Conditions

(Hedge (Hedge (Hedge (Hedge et alet alet alet al., ., ., ., Indoor AirIndoor AirIndoor AirIndoor Air, 1993), 1993), 1993), 1993)

0102030405060708090

100

Poor IA Q Too littleair

m ovem ent

Insufficientventilation

Stale air Air toodus ty

A ir too dry Unp leasantod ors

%

Pre-control Post-control Pre-BZF Post-BZF

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© Alan Hedge 11/00

BZF and PIAQ Effects on Productivity BZF and PIAQ Effects on Productivity BZF and PIAQ Effects on Productivity BZF and PIAQ Effects on Productivity (Hedge (Hedge (Hedge (Hedge et alet alet alet al., ., ., ., Indoor AirIndoor AirIndoor AirIndoor Air, 1993), 1993), 1993), 1993)

0

10

20

30

40

50

60

70

80

90

100

Poor IAQ Too little air

m ovem ent

Insufficient

ventilation

Stale air Air too

dusty

A ir too dry

% r

ep

ort

ing

de

cre

ase

d p

rod

uct

ivit

y

P re-contro l Post-control Pre-BZF Post-BZF

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© Alan Hedge 11/00

BZF and SBS symptoms BZF and SBS symptoms BZF and SBS symptoms BZF and SBS symptoms (Hedge (Hedge (Hedge (Hedge et alet alet alet al., ., ., ., Indoor AirIndoor AirIndoor AirIndoor Air, 1993), 1993), 1993), 1993)

0.000.501.001.502.002.503.003.504.004.505.00

P re-control

P ost-control

P re-B ZF Post-BZF P la ceb o

Me

an

PS

I


Slide 25

© Alan Hedge 11/00

BZF and SBS Effects on Productivity BZF and SBS Effects on Productivity BZF and SBS Effects on Productivity BZF and SBS Effects on Productivity (Hedge (Hedge (Hedge (Hedge et alet alet alet al., ., ., ., Indoor AirIndoor AirIndoor AirIndoor Air, 1993), 1993), 1993), 1993)

0

10

20

30

40

50

60

70

80

90

100

Dry eyes Irritated,sore eyes

Tired,strained

eyes

Stuffy nose Runny nose Lethargy

%

P re -control Po s t-co ntrol P re -BZF P os t-B ZF

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© Alan Hedge 11/00

Benefits of BZFBenefits of BZFBenefits of BZFBenefits of BZF

• BZF provides continuous, controllable, clean air to each employee.

• BZF compliments HVAC performance and improves air mixing in cubicles.

• BZF protects employees against transient air pollutants.

• BZF reconfigures with "office churn".

• BZF improves IAQ and reduces SBS complaints.

• BZF improves productivity.

Slide 27

© Alan Hedge 11/00

Office Lighting IssuesOffice Lighting IssuesOffice Lighting IssuesOffice Lighting Issues

• Computer Vision Syndromeis the #1 complaint of computerized office workers


Slide 28

© Alan Hedge 11/00

Lighting and Eyestrain:Lighting and Eyestrain:Lighting and Eyestrain:Lighting and Eyestrain:Sources of GlareSources of GlareSources of GlareSources of Glare

• Overhead lightsOverhead lightsOverhead lightsOverhead lights

• Task lightsTask lightsTask lightsTask lights

• WindowsWindowsWindowsWindows

• Reflective sources Reflective sources Reflective sources Reflective sources (clothing, paper)(clothing, paper)(clothing, paper)(clothing, paper)

• Computer screenComputer screenComputer screenComputer screen

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© Alan Hedge 11/00

Computer Use and Eye SymptomsComputer Use and Eye SymptomsComputer Use and Eye SymptomsComputer Use and Eye Symptoms

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0.5 1 2 3 4 5 6 7 7.5

H rs. com pute r use

Mea

n #

eye

sym

ptom

s

Me nW om en

(Hedge et al., ASHRAE Proc., 1991)

(n=4,479)

Slide 30

© Alan Hedge 11/00

Office Lighting SystemsOffice Lighting SystemsOffice Lighting SystemsOffice Lighting Systems


Slide 31

© Alan Hedge 11/00

Indirect vs. Direct LightingIndirect vs. Direct LightingIndirect vs. Direct LightingIndirect vs. Direct Lighting

• The eye doesn’t see illuminance!

Slide 32

© Alan Hedge 11/00

Cornell Lighting Study:Cornell Lighting Study:Cornell Lighting Study:Cornell Lighting Study: Xerox FacilityXerox FacilityXerox FacilityXerox Facility(Hedge (Hedge (Hedge (Hedge et alet alet alet al., ., ., ., ErgonomicsErgonomicsErgonomicsErgonomics, 1995), 1995), 1995), 1995)

Slide 33

© Alan Hedge 11/00

OpenOpenOpenOpen----office Koffice Koffice Koffice K----12 Lighting12 Lighting12 Lighting12 Lighting(Hedge (Hedge (Hedge (Hedge et alet alet alet al., ., ., ., ErgonomicsErgonomicsErgonomicsErgonomics, 1995), 1995), 1995), 1995)


Slide 34

© Alan Hedge 11/00

Cornell/Xerox: Lighting Changes Cornell/Xerox: Lighting Changes Cornell/Xerox: Lighting Changes Cornell/Xerox: Lighting Changes (Hedge (Hedge (Hedge (Hedge et alet alet alet al., ., ., ., ErgonomicsErgonomicsErgonomicsErgonomics, 1995), 1995), 1995), 1995)

K12 lens

Parabolic

Lensed-indirect

Slide 35

© Alan Hedge 11/00

Parabolic Gloom! Parabolic Gloom! Parabolic Gloom! Parabolic Gloom! (Hedge (Hedge (Hedge (Hedge et alet alet alet al., ., ., ., ErgonomicsErgonomicsErgonomicsErgonomics, 1995), 1995), 1995), 1995)

Private Offices

Open-Plan Offices

Slide 36

© Alan Hedge 11/00

LensedLensedLensedLensed----Indirect Lighting Indirect Lighting Indirect Lighting Indirect Lighting (Hedge (Hedge (Hedge (Hedge et alet alet alet al., ., ., ., ErgonomicsErgonomicsErgonomicsErgonomics, 1995), 1995), 1995), 1995)

• Overwhelming preference for indirect lighting.

• % reporting daily work-related health complaints twice as great with direct PB lighting.

Lighting Preferences

0102030405060708090

P re fe r L ILP re fe r L ILP re fe r L ILP re fe r L IL P re fe r P B LP re fe r P B LP re fe r P B LP re fe r P B L

Group

%

LIL PB L


Slide 37

© Alan Hedge 11/00

Two-Component

Lighting Study

The Norwegian Trade Council, NY.

Slide 38

© Alan Hedge 11/00

PrePrePrePre----Installation OfficesInstallation OfficesInstallation OfficesInstallation Offices

Interior office Perimeter office

Offices

Slide 39

© Alan Hedge 11/00

Office Office Office Office PhotometricsPhotometricsPhotometricsPhotometrics

• Distribution of evening light levels in the office space.


Slide 40

© Alan Hedge 11/00

Cubicle OfficesCubicle OfficesCubicle OfficesCubicle Offices• Individually controllable wall sconce indirect fixture

on side panel and on each mullion between cubicles.

• Desktop adjustable, asymmetric task light.

Slide 41

© Alan Hedge 11/00

Lighting Quality Ratings Lighting Quality Ratings Lighting Quality Ratings Lighting Quality Ratings ((((P<0.05))))

1 2 3 4 5 6 7

good/bad

dim/bright

attractive/unattrac tive

pleasant/unpleasant

calm/aroused

harsh/soft

relaxed/tense

interes ting/boring

Mean rating

D irect2-co m po nen t

Slide 42

© Alan Hedge 11/00

Reactions to 2Reactions to 2Reactions to 2Reactions to 2----component Lightingcomponent Lightingcomponent Lightingcomponent Lighting

0 20 40 60 80 100

% Agree% Agree% Agree% Agree

Meetings at desk

Reading documents

W riting on paper

Seeing screen text

Seeing screen graph ics

> Good


Slide 43

© Alan Hedge 11/00

Opinions of 2Opinions of 2Opinions of 2Opinions of 2----component Lightingcomponent Lightingcomponent Lightingcomponent Lighting

0 20 40 60 80 100

% Agree

L ike having ligh tingcon trol

O ffice looks n icer

L ike new ligh ting

O ffice feels b righ ter

Less eyestrain

Easier to readscreen

Slide 44

© Alan Hedge 11/00

DualDualDualDual----component Lightingcomponent Lightingcomponent Lightingcomponent Lighting• Worker reaction to the use of dual-component

lighting systems is very positive.

• Workers require training.

Slide 45

© Alan Hedge 11/00

Cornell Cornell Cornell Cornell Glare Filter Glare Filter Glare Filter Glare Filter

StudyStudyStudyStudy(Hedge (Hedge (Hedge (Hedge et alet alet alet al., ., ., ., HFES Proc.,HFES Proc.,HFES Proc.,HFES Proc.,

1996)1996)1996)1996)


Slide 46

© Alan Hedge 11/00

Reactions to Health SymptomsReactions to Health SymptomsReactions to Health SymptomsReactions to Health Symptoms(Hedge (Hedge (Hedge (Hedge et alet alet alet al., ., ., ., HFES Proc.,HFES Proc.,HFES Proc.,HFES Proc., 1996)1996)1996)1996)

% response

0 10 20 30 40 50 60 70 80 90 100

y

s

s

g

s

Letharg

Tired eye

Troublefocussing eye

Itching/waterineyes

Dry eye

Headache

Survey 3Survey 1

Slide 47

© Alan Hedge 11/00

Good Ergonomics is Good Ergonomics is Good Ergonomics is Good Ergonomics is Great EconomicsGreat EconomicsGreat EconomicsGreat Economics

• Ergonomics is always a benefit.• Ignorance of ergonomics is the cost!

Slide 48

© Alan Hedge 11/00

Cornell University Ergonomics WebCornell University Ergonomics WebCornell University Ergonomics WebCornell University Ergonomics Webhttp://ergo.human.http://ergo.human.http://ergo.human.http://ergo.human.cornellcornellcornellcornell....eduedueduedu

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