Eye Disease Resulting From Increased Use of Fluorescent Lighting as a Climate Change Mitigation Strategy

Abstract

Increased use of fluorescent lighting as a climate change mitigation strategy may increase eye disease. The safe range of light to avoid exposing the eye to potentially damaging ultraviolet (UV) radiation is 2000 to 3500K and greater than 500 nanometers. Some fluorescent lights fall outside this safe range.
Fluorescent lighting may increase UV-related eye diseases by up to 12% and, according to our calculations, may cause an additional 3000 cases of cataracts and 7500 cases of pterygia annually in Australia.
Greater control of UV exposure from fluorescent lights is required. This may be of particular concern for aging populations in developed countries and countries in northern latitudes where there is a greater dependence on artificial lighting.

Full text

Eye Disease Resulting From Increased Use of Fluorescent
Lighting as a Climate Change Mitigation Strategy
Increased use of fluores-
cent lighting as a climate
change mitigation strategy
may increase eye disease.
The safe range of light to
avoid exposing the eye to
potentially damaging ultra-
violet (UV) radiation is 2000
to 3500 K and greater than
500 nanometers. Some fluo-
rescent lights fall outside
this safe range.
Fluorescent lighting may
increase UV-related eye dis-
easesbyupto12%and,ac-
cording to our calculations,
may cause an additional 3000
cases of cataracts and 7800
cases of pterygia annually in
Australia.
Greater control of UV ex-
posure from fluorescent
lights is required. This may
be of particular concern for
aging populations in deve-
loped countries and coun-
tries in northern latitudes
where there is a greater de-
pendence on artificial light-
ing. (Am J Public Health.
Published online ahead of
print October 20, 2011:
e1–e4. doi:10.2105/AJPH.
2011.300246)
Helen L. Walls, PhD, MPH, Kelvin L. Walls, PhD, and Geza Benke, PhD
CLIMATE CHANGE MITIGATION
will involve numerous changes in
the use of technology. Many peo-
ple worldwide are exposed to ar-
tificial light sources both in the
home and in the workplace. Until
recently, this mainly entailed ex-
posure to incandescent lights and,
less frequently, to fluorescent
lighting. Moves to sustainability
and a low-carbon economy have
involved the phasing out of in-
candescent lights and a shift to-
ward more energy-efficient light-
ing in a number of countries,
including Australia and the coun-
tries of the European Union.
1, 2
In
the United States, federal law
stipulates that incandescent lights
be phased out by 2014.
3
Globally, increasing numbers of
workers spend their work time in
buildings rather than in fields or
other outside locations and are
thus, regularly and for extended
periods, exposed to ultraviolet
(UV) radiation via fluorescent
lighting. This increase is partly due
to rapid urbanization and the in-
creasingly knowledge-based soci-
ety (attracting workers into offices)
in which we live. Although fluo-
rescent lighting has been used in
schools and offices for many years,
only in recent years has it domi-
nated UV exposure in the home,
and it will continue to do so in
future years.
The types of energy-efficient
lighting with which incandescent
lights are being replaced are high-
intensity discharge (HID) lamps,
light-emitting diodes (LEDs), and
fluorescent lighting, including the
popular compact fluorescent
lamps (CFLs). All of these light
sources are more efficient than the
incandescent lamp, which electri-
cally heats a tungsten filament so
that it glows but loses much en-
ergy as heat.
4
CFLs, for example,
use 75% less energy than do in-
candescent lamps.
5
HID lamps produce intense
light in a small area, and although
they are less energy efficient than
fluorescent lights, they are used
widely for lighting large areas such
as streets and sports facilities.
6
LEDs are energy efficient but not
as bright, stable, or cheap as fluo-
rescent lights. Fluorescent lighting,
with its minimal energy demands,
is considered to provide the most
efficient form of light, one that
most closely resembles daylight
and provides the visual acuity
necessary for task performance.
Consequently, as a result of the
popularity of fluorescent lighting
a large number of people are now
exposed to artificial sources of UV
radiation emitted from these
lights. Could this be a precursor to
a substantial increase in future
eye disease? We examine the po-
tential for such an increase.
FLUORESCENT LIGHTING
AND ULTRAVIOLET
RADIATION
A fluorescent lamp or tube is
a gas-discharge device that uses
electricity to excite mercury vapor.
The excited mercury atoms pro-
duce UV radiation, which causes
the phosphorescent coating inside
the tube to fluoresce, producing
visible light. Manufacturers can
vary the color of the light given off
by the tube by manipulating the
mixture of phosphors, and the
spectrum of light emitted is a com-
bination of light directly emitted
by the mercury vapor and light
emitted by the phosphorescent
coating. The amount and wave-
length of the UV radiation emitted
from such lamps vary widely.
7
The fluorescent lighting used
indoors is often in the form of
cool white tubes with a color
temperature of about 4000K. (If
each light requires 18 watts, the
lamps are usually supplied as a
pair of 9-watt tubes because 2
lamps cancel out any flicker.) CFLs
vary in terms of color tempera-
ture, and there are variations
and inconsistencies among manu-
facturers. However, the warmer
CFLs, which are usually less than
3500K, produce light that is gen-
erally not adequate for concen-
tration at work. Cool white CFLs,
at 4000K or greater, are more
commonly used in commercial
settings. Table 1 describes the
types of fluorescent lights and
associated color temperatures.
8
The market share of fluores-
cent lighting varies considerably
among countries, ranging from
6% in the United States to 20% in
the United Kingdom and 50% in
Germany in 2007, for example.
9
In US commercial buildings, use
of incandescent lamps decreased
(from 58% to 54%) between
1992 and 2003, as did use of
fluorescent lamps (from 91% to
83%), whereas there were in-
creases in the use of CFLs (from
12% to 38%) and HID lamps
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Copyright 2011 by the American Public Health Association

(from 26% to 29%).
4
In many
countries, there is still a high po-
tential for increased use of fluo-
rescent lighting.
Fluorescent lighting operating
above a color temperature of
4000K, which is associated with
wavelengths of less than 380 to
500 nanometers within the UV
range, is hazardous to the ocular
tissues. Clarkson identified the
6000K and 400- to 500-nano-
meter combination as a particu-
larly hazardous one, causing
damage to the retina.
10
The safe
range of light, to avoid exposing
the eye to potentially damaging
UV light, is approximately 2000 to
3500K and greater than 500
nanometers. The warmer incan-
descent lights are usually less than
3500K and are less damaging to
the eye, but they often produce
light that is inadequate for con-
centrating at work.
Fluorescent lights emit UV ra-
diation whose irradiance is equal
to or greater than that of sunlight
at wavelengths of approximately
290 to 295 nanometers but not at
longer wavelengths.
11,12
However,
there is a fair amount of variation
in UV emissions between lamps
of similar voltage. Hartman and
Biggley studied 15-watt fluores-
cent lamps used in homes and
detected greater than 10-fold dif-
ferences in ultraviolet-B (UV-B)
and ultraviolet-C (UV-C) emissions
between lamps (ranging from 0.9
and 0.4 lW/cm
2
to 21.0 and 1.5
lW/cm
2
for UV-B and UV-C
emissions, respectively), with a 23-
fold variance for UV-B.
7
Other
studies have also revealed wide
variances in fluorescent light UV
emissions.
The sensitivity of the eye to
short electromagnetic wave-
lengths not perceived as visible
light is important. Absorption of
too much short-wavelength UV
light can damage ocular tissues by
changing the chemical structure of
biomolecules.
13
UV wavelengths
less than 500 nanometers (and
certainly less than 380 nm) are
capable of irreparable damage to
the eye.
10
Cumulative dose is also an
important component of UV ex-
posure. Literature based on occu-
pational exposures generally as-
sumes exposures of between 8 and
12 hours per day, or 40 hours per
week. Such durations are also
well within the normal range for
domestic exposures.
ULTRAVIOLET RADIATION
AND EYE DISEASES
UV radiation has been consid-
ered a cause of cataracts and
pterygia.
14
There is also now
a significant body of literature
describing an association be-
tween UV radiation from the sun
and degenerative eye diseases
such as age-related macular de-
generation (AMD).
10, 13 --- 21
Early
reports suggested that the high-
energy segment of the visible re-
gion (400---500 nm) is markedly
more hazardous than the low-
energy portion (500---700 nm).
22
Andley and Chylack reported that
the risk of light damaging the
retina increases with decreasing
wavelength from 500 to 400
nanometers.
23
In Canada, it was
reported that AMD, the most
common cause of blindness in
the developed world, is likely to
be associated with chronic ex-
posure to ultraviolet-A (UV-A)
radiation.
16
Shaban and Richter reported
that the photoreceptors in the
retina are susceptible to damage
by light, particularly UV light, and
that this damage can lead to cell
death and disease.
24
Paskowitz
et al. also suggested such photo-
receptor damage, reporting that
rods are affected earlier than
cones.
25
Norval et al. linked acute
or long-term eye damage to ozone
depletion, which leads to an in-
crease in UV radiation reaching
the Earth’s surface.
26
There is also a general public
awareness that UV radiation
from the sun, sustained in normal
daylight conditions, can damage
the eye. For example, most people
are aware of the importance
of not looking directly at the
sun, and operators of arc weld-
ers know to wear protective
goggles.
16,27,28
Less attention has been paid to
the potentially damaging effects of
UV radiation people are exposed
to indoors, in particular fluores-
cent lighting, even though such
exposures are a significant source
of potentially hazardous UV light.
In the past, welding processes
and lasers have been the indoor
sources of UV radiation of most
concern. In a recent report, how-
ever, Sharma et al. warned
against the use of close-range
fluorescent lighting, such as desk
lamps, to obviate the risks posed
by UV-A.
29
FLUORESCENT LIGHTING
AND IMPACT ON RATES OF
EYE DISEASE
The elimination of incandescent
lighting and the move worldwide
to fluorescent lighting in recent
years can be attributed to more
acute awareness regarding future
climate change concerns.
2
In Aus-
tralia, it has been estimated that
with this change in lighting type
there will be a reduction of ap-
proximately 30 terawatt hours of
electricity and 28 million tons of
greenhouse gas emissions be-
tween 2008 and 2020. Because
Australia accounts for only about
1.8% of greenhouse gases world-
wide, a global move toward fluo-
rescent lighting in the home will
lead to significant reductions in
greenhouse gases.
30
However, such shifts may in-
crease the population burden of
eye disease, and a crude estimate
of the number of excess cases of
eye disease in Australia caused
by fluorescent lighting can be
calculated. The prevalence of
cataracts in the Australian pop-
ulation is approximately 31%
TABLE 1—Types of Fluorescent Lights and Associated Color
Temperatures
Type of Light Example
Approximate Color
Temperature, K
Warm ( < 3200K) Incandescent fluorescent 2750
Deluxe warm white 2900
Warm white 3000
Medium (3200–4000K) White 3450
Natural white 3600
Cool (> 4000K) Deluxe cool white 4100
Lite white 4150
Cool white 4200
Daylight 6300
Deluxe daylight 6500
Octron Skywhite (Sylvania) 8000
Note. Daylight is approximately 6000K (although with considerable variation).
Source. Information was adapted from Sizes Inc.
8
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among individuals 55 years old
or older,
31
and the prevalence of
pterygia is about 7.3% among
those 49 years old or older.
32
In
2007, approximately 6.5 million
residents of Australia were older
than 49 years, and 5.1 million
were older than 55 years.
33
Re-
cently, Lucas et al.
14
reported
population-attributable fractions
of 0.05 for cataracts associated
with UV radiation and at least
0.42 for pterygia associated with
UV radiation.
Unfortunately, there are no
published estimates of the per-
centage increase in UV exposure
with increased exposure to fluo-
rescent lighting, but previously
published estimates for work-
place exposures may provide
a guide. Lytle et al. estimated that,
among indoor workers in the
United States, lifetime exposure
to typical fluorescent lighting
(unfiltered) at an average inten-
sity of 1.2 kilojoules per square
meter per year (although Lytle
et al. reported uncertainties in
indoor UV exposures) may in-
crease the risk of solar UV radia-
tion by 3.9% (95% confidence
interval [CI ] =1.6%, 12.0%).
34
Lifetime exposure was defined as
that occurring over two thirds of
a lifetime (40 years of employ-
ment and 16 years of schooling,
where 1 school year is approxi-
mately 0.6 of a work year, that
is, 1200 hours vs 2000 hours).
Thus, conservative estimates of
the number of additional annual
cases of cataracts and pterygia in
Australia associated with UV ra-
diation from fluorescent lighting
would be 2970 and 7480, re-
spectively.
RECOMMENDATIONS
The replacement of incandes-
cent lamps with fluorescent light-
ing appears to be a global trend.
However, this change in lighting
sources may lead to an increase in
eye diseases unless there is greater
control of UV exposures from
many of the fluorescent lights
currently in use or technological
advances enabling efficient light-
ing from other sources. For Aus-
tralia alone, we estimate at least
10 000 additional cases of eye
disease each year. Our estimates
are conservative and crude in that
they are limited by the poor in-
formation currently available with
regard to the incidence and etiol-
ogy of many eye diseases. We
have not included in our estimates
possible increases in AMD be-
cause there is not yet universal
agreement in the literature re-
garding causality with UV radia-
tion. But if a link between UV
radiation and AMD is firmly
established in the future, this
would have significant public
health implications.
Kitchel commented that ‘‘seri-
ous consideration as to how we
light environments of persons with
visual problems cannot come too
soon’’ and suggested that such in-
dividuals should avoid environ-
ments where the predominant
light waves are of a color temper-
ature greater than 3500K or
a wavelength less than approxi-
mately 500 nanometers.
35
Clark-
son supported this 500-nanome-
ter threshold limit.
10
Kitchel also
suggested that UV light causes
irreparable damage over time to
the human retina, especially in
young children,
35
a public health
issue that has not been investi-
gated.
The evidence suggests that the
least hazardous approach to light-
ing is to use warm-white tubes or
incandescent bulbs of lower color
temperature and longer wave-
length light rather than fluorescent
lamps. With incandescent bulbs
and warm-white tubes, the eye is
not subject to potentially damag-
ing UV radiation from fluorescent
lighting. The difficulty is that any-
thing other than fluorescent light-
ing is considered inadequate for
many workplaces and in the home.
UV filters, available for some
fluorescent lights that are manu-
factured with UV diffusers, should
become a required standard. Fur-
thermore, we support the sugges-
tion of Hartman and Biggley that
lamp manufacturers should not
allow current levels of emission of
UV light from fluorescent lighting
to increase and should work to-
ward reductions in emissions.
7
The safe range of light, to avoid
exposing the eye to potentially
damaging UV radiation, appears
to be between 2000 and 3500K
and a wavelength of greater
than 500 nm. Some fluorescent
lights currently fall outside this
safe range. This may increase
UV-related eye diseases by up to
12% (estimate of 3.9%; 95%
CI =1.6%, 12.0%) an d result in
unforeseen adverse public health
consequences. There is a conflict
between climate change miti-
gation through elimination of
incandescent lights and the un-
regulated use of primarily fluo-
rescent lighting.
In our experience, lighting sup-
ply wholesalers and retailers are
generally not adequately aware of
the full characteristics of their
products, such as color tempera-
ture and wavelengths of emitted
light. Consumers and users of
fluorescent lights are relatively
unaware of the fact that these
lights emit UV light and that this
light could be harming their eyes.
In response, we advocate for
the use of incandescent and
warm-white lamps instead of
cool-white fluorescent lamps, as
well as for further research into
improving lighting from such
sources. This public health issue
may be of particular concern for
aging populations, such as those
of many developed countries and
countries in northern latitudes
where there is a greater depen-
dence on artificial lighting. j
About the Authors
At the time of this study, Helen L. Walls
and Geza Benke were with the Department
of Epidemiology & Preventive Medicine,
Monash University, Melbourne, Victoria,
Australia. Kelvin L. Walls was with
Building Code Consultants Limited, New-
market, Auckland, New Zealand.
Correspondence should be sent to Helen
L. Walls, PhD, MPH, National Centre for
Epidemiology & Population Health,
Australian National University, Canberra,
Australian Capital Territory, Australia
(e-mail: helen.walls@anu.edu.au). Reprints
can be ordered at http://www.ajph.org by
clicking the ‘‘Reprints/Eprints’’ link.
This article was accepted March 23,
2011.
Contributors
H. L. Walls and K. L. Walls drafted the
original article. G. Benke provided
further interpretation. All of the authors
helped formulate concepts and contributed
to drafts of the article.
Acknowledgments
H. L. Walls is supported by the National
Health and Medical Research Council
(NHMRC; grant 465130). K. L. Walls is
supported by Building Code Consultants
Limited. G. Benke is supported by an
NHMRC Career Development Award.
Human Participant Protection
No protocol approval was needed for this
study because no human subjects were
involved.
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