vvEPA
United States
Environmental Protection
Agency
National Risk Management
Research Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/SR-01/001 January 2001
Project Summary
Candles and Incense as Potential
Sources of Indoor Air Pollution:
Market Analysis and Literature
Review
Lynn Knight, Arlene Levin, and Catherine Mendenhall
The report summarizes available in-
formation on candles and incense as
potential sources of indoor air pollution.
It covers market information and a re-
view of the scientific literature. The
market information collected focuses
on production and sales data, typical
uses in the U.S., and data on the sources
and quantities of imported products. The
estimated total sales of candles in 1999
varied between $968 million and $2.3
billion, while imports were $486 million.
The U.S. imports and exports of incense
in 1999 were $12.4 and 4.6 million, re-
spectively. The scientific literature re-
view gathered information regarding the
emission of various contaminants gen-
erated when burning candles and in-
cense, as well as the potential health
effects associated with exposure to
these contaminants. Burning candles
and incense can be sources of particu-
late matter. Burning candles with lead-
core wicks may result in indoor air
concentration of lead above EPA-rec-
ommended thresholds. Exposure to in-
cense smoke has been linked with
several illnesses, and certain brands of
incense also contain chemicals sus-
pected of causing skin irritation.
This Project Summary was developed
by the National Risk Management Re-
search Laboratory's Air Pollution Pre-
vention and Control Division, Research
Triangle Park, NC, to announce key find-
ings of the research project that is fully
documented in a separate report of the
same title (see Project Report ordering
information at back).
Background and Approach
The potential indoor air impacts of burn-
ing candles and incense have drawn in-
creased attention in recent years. There
are three particular areas of concern.
Candles with lead-core wicks have been
found on the market and have been
shown to be a source of airborne lead
when burned. Metal cores are used to
stiffen wicks so they will not fall over and
extinguish themselves as the surround-
ing wax melts. Lead was commonly used
as a core material until 1974 when the
U.S. candle manufacturing industry vol-
untarily agreed to discontinue use of lead
in wicks. However, candles with lead
wicks have been found on the market by
an academic as well as a consumer pro-
tection group study. Most of the candles
found that contained lead wicks were im-
ported.
Secondly, under imperfect combustion
conditions, candles emit soot and can
cause property damage by blackening
walls, ceilings, and carpets. There have
been an increasing number of complaints
regarding black soot deposition in homes
in the last decade. Candles are one
source of soot. With candles, sooting oc-
curs as a result of incomplete combus-
tion. Candle composition, wick length, and
drafty conditions can all affect candle com-
bustion. The amount of soot produced
can vary greatly depending on the type of
candle. One type of candle can produce
as much as 100 times more soot than
another.
Thirdly, incense smoke can be a major
source of particulate emissions in indoor
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air. The particulates produced when burn-
ing incense can deposit in the respiratory
tract. These emissions may contain con-
taminants that can cause a variety of
health effects, including mutagenic effects
and airborne dermatitis.
EPA is currently testing emissions from
candles and incense to generate data.
To support this effort, the report collects
and presents two types of data: (1) mar-
ket information, and (2) literature on the
potential impacts of burning candles and
incense on indoor air quality.
The market information collected fo-
cuses on production and sales data, typi-
cal uses in the U.S., and data on the
sources and quantities of imported prod-
ucts. In addition, the report summarizes
the results of a scientific literature review.
It reports the findings in the scientific lit-
erature regarding the emission rates of
the various contaminants generated when
burning candles and incense, as well as
the potential health effects associated with
exposure to these contaminants.
Market Information
Publicly available sources of data,
mostly from the U.S. Bureau of the Cen-
sus, as well as private market studies
and trade literature were consulted to pro-
duce this summary of economic informa-
tion regarding the candle and incense
markets. Dialog Information Service and
Internet searches were performed to iden-
tify market and related information. The
U.S. Bureau of Census was contacted to
obtain import and export data. The Na-
tional Candle Association was contacted
to obtain industry data.
The Census Bureau reports 107 manu-
facturing establishments; however, indus-
try estimates range from 160 to over 200
manufacturers. Many manufacturers are
very small. Candle sales have been grow-
ing rapidly in the last 10 years (10 to 15
% per year), fueled by consumer interest
in aromatherapy and increased demand
for home fragrance products in general.
There is a wide range in estimates of
candle sales in the U.S. The Census Bu-
reau reports a total value of shipments in
1997 of $968 million; industry estimates
put 1999 sales at $1.3 billion just for
scented candles, and up to $2.3 billion
for all candles. The majority of candle
imports are from China. A large portion of
imports come from Hong Kong, Mexico,
and Canada as well.
There are no public data on incense
manufacturers; private data show at least
26 manufacturers. Limited discussions
with industry representatives indicate that
there are probably many more very small
incense manufacturers. The majority of
incense imports are from India, China,
and Thailand.
Potential Indoor Air Quality
Impacts
Scientific literature, consumer interest
group reports, and trade and industry stud-
ies were consulted for this summary. Re-
sources were identified through Medline,
Toxline, a database of on-line journals,
the National Candle Association, and ex-
tensive web searches. The studies were
diverse in origin; many of the incense
studies were performed in Asia, where
incense is commonly burned.
Candles
According to the literature reviewed,
burning candles containing lead-core
wicks can result in indoor air concentra-
tions of lead above EPA-recommended
thresholds. All three of the scientific stud-
ies, found analyzing indoor air concen-
trations resulting from burning candles
with lead-core wicks, indicated that this
indoor air threshold was exceeded. Re-
garding candles with non-lead metal
cores, the literature did not indicate that
wicks made with zinc and tin emitted these
metals at concentrations that would raise
health concerns when burned indoors.
In addition to lead, consumers are ex-
posed to concentrations of organic chemi-
cals, such as formaldehyde, acetaldehyde,
and acrolein. One study showed worst-
case scenario candle emissions contain-
ing levels of these three chemicals that
exceeded EPA-recommended thresholds.
Other studies indicated no health hazards.
Sooting can occur when combustion
conditions are impaired when burning
candles. Scented candles are more likely
to produce soot than unscented candles.
Sooting can cause property damage by
blackening surfaces. Although soot par-
ticles are very small and can potentially
penetrate the deepest areas of the lungs,
studies regarding potential human health
effects associated with soot from candles
were not found in the literature search.
Incense
Large quantities of particulate matter
are generated when burning incense.
Studies that examined the emissions of
specific contaminants from incense smoke
indicated that benzene and carbon mon-
oxide may be emitted at concentrations
that could pose human health risks. Sev-
eral studies indicated links between ex-
posure to incense smoke and health
effects, such as cancer, asthma, and con-
tact dermatitis. Some studies indicated
possible mutagenic and genotoxic effects.
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L Knight, A. Levin, and C. Mendenhall are with Eastern Research Group, Lexington, MA
02421-3136.
Zhishi Quo is the EPA Project Officer (see below).
The complete report, entitled "Candles and Incense as Potential Sources of Indoor Air
Pollution: Market Analysis and Literature Review," (Order No. PB2001-103 924; Cost:
$27.00, subject to change) will be available only from
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: (703) 605-6000 (world wide)
(800) 553-6847 (U.S. only)
The EPA Project Officer can be contacted at
Air Pollution Prevention and Control Division
National Risk Management Research Laboratory
U. S. Environmental Protection Agency
Research Triangle Park, NC 27711-0001
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
PRESORTED STANDARD
POSTAGES FEES PAID
EPA
PERMIT No. G-35
Official Business
Penalty for Private Use
$300
EPA/600/SR-01/001
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