Sensitivity for subliminal flicker

Adverse effects of subliminal flicker

•Headache

•Stress

•Arousal of CNS

Hypotheses

• Flicker elimination with HF-ballasts has a stress reducing effect

• Flicker reduction is also beneficial for those who describe other kinds of building- and work-place related symptoms

• Individuals with high CFF is more sensitive than others

O1 XChange of tubes

O2 YMeasurement CFF

Yr 1 Yr 2

Measurements

Physical

Illuminance

Luminance

Electrical and magnetic fields

Individual

Experience of the work environment

Complaints

Personality

CFF

Subjects

Experimental group

3 work places

7 men 35 women

Mean age 47 years

Control group

7 work places

150 men 140 women

Mean age 46 years

RESULTS

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Before After

Figure 1. Index Anxiety and stress before and after the change of tubes p=.022, N = 42

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Before After

Figure 2. Variabel stress before and after change of tubes. p = .024., N = 42

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Before After

Figure 3. Index Eye problems before and after the change of tubes p=.006, N = 42

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Before Afer

Figure 4. BWRS index before and after the change of tubes. p = .002., N = 42

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L o w C F F H ig h C F F

B e f o r e

A f t e r

L ig h tin g q u a lity

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1

Eye index

HF-ballasts Conventional

Tabell 1. Stepwise multiple regression analysis with environmental variables (subjective and objective) and background variables as independent and the total complaint index as dependent variable (only significant values are seen in the table). N = 374 Variabel R2 β p Dry air .214 .266 .000 Tiresome work positions .085 .219 .000 Reflexes from VDU .032 .137 .000 Draught .019 .132 .003 Ballasts (1=HF, 2=conventional) .014 -.123 .010 Static electricity .009 .103 .038 R2 .372

Conclusions

• Subliminal flicker causes stress and eye-problems at the work place

• There is a tendency toward the existence of a more sensititve group

• Flicker maybe a component in the so-called Sick Building Syndrome

• More knowledge about the mechanisms causing the effects