POSITION TITLE: RESIDENTIAL WOOD COMBUSTION
DATE APPROVED: APRIL 24, 1999
COMMITTEE: NATIONAL AIR CONSERVATION COMMISSION / SCIENTIFIC ASSEMBLY ON ENVIRONMENTAL AND OCCUPATIONAL HEALTH
POSITION SUBJECT: AIR CONSERVATION
POSITION TEXT: THE AMERICAN LUNG ASSOCIATION CALLS FOR EFFECTIVE ENFORCEMENT OF EXISTING REGULATIONS AND ORDINANCES GOVERNING WOOD BURNING AND ENCOURAGES OR THE ENACTMENT OF SUCH, WHERE NEEDED TO PROTECT PUBLIC HEALTH.
THE AMERICAN LUNG ASSOCIATION ENCOURAGES THE UNITED STATES ENVIRONMENTAL
PROTECTION AGENCY (U. S. EPA), UNDER SECTION 111 OF THE CLEAN
AIR ACT, TO RE-EVALUATE ITS WOODSTOVE CERTIFICATION STANDARDS
WITH AN EYE TOWARD SUBSTANTIALLY STRENGTHENING THEM OVER TIME,
REVISING THEM IN LIGHT OF THE MOST RECENT HEALTH DATA ON WOODSMOKE
POLLUTION AND THE NATIONAL AMBIENT AIR QUALITY STANDARDS FOR
PARTICULATE MATTER AIR POLLUTION.
IN ADDITION, INDIVIDUALS SHOULD AVOID BURNING WOOD IN HOUSES WHERE LESS POLLUTING HEATING ALTERNATIVES ARE AVAILABLE. THE USE OF THE LEAST-POLLUTING ALTERNATIVE HEATING METHODS AND CLEANER TECHNOLOGIES SHOULD BE PROMOTED TO PROVIDE USEFUL HEAT, WHILE MINIMIZING ANY ADVERSE HEALTH EFFECTS.
THE AMERICAN LUNG ASSOCIATION SUPPORTS POLICIES THAT MINIMIZE THE PUBLIC HEALTH IMPACT OF RESIDENTIAL WOODBURNING. EMISSIONS OF AIR CONTAMINANTS FROM WOODBURNING SHOULD BE REDUCED OR ELIMINATED, BOTH OUTDOORS AND INDOORS, SO EXPOSED POPULATIONS ARE NOT SUBJECTED TO CONCENTRATIONS OF POLLUTANTS THAT ADVERSELY AFFECT HEALTH.
BECAUSE OF THE NATURE AND PREVALENCE OF WOODSMOKE POLLUTION AND ITS HEALTH EFFECTS, THE AMERICAN LUNG ASSOCIATION RECOMMENDS THAT MORE RESOURCES BE DEVOTED TO RESEARCH, SPECIFICALLY IN THE FOLLOWING AREAS:
1) THE PREVALENCE AND RELATIVE IMPORTANCE OF
WOODSMOKE AS A COMPONENT OF AIR POLLUTION
IN RESIDENTIAL AREAS ACROSS THE COUNTRY;
2) THE ACUTE, CHRONIC, AND POTENTIAL CARCINOGENIC
HEALTH EFFECTS OF WOODSMOKE POLLUTION, IN
CHILDREN AND ADULTS, ESPECIALLY AMONG THOSE
WITH PREEXISTING CARDIOPULMONARY DISEASE;
AND
3) THE RELATIVE IMPORTANCE OF WOODSMOKE IN
CONTRIBUTING TO INCREASED MORTALITY, MORBIDITY, AND CERTAIN WELL-DEFINED
ADVERSE HEALTH OUTCOMES, BOTH NATIONALLY AND WITH ATTENTION TO
CERTAIN AFFECTED LOCALITIES.
BACKGROUND:
IN MOST AREAS OF THE COUNTRY, WOOD COMBUSTION IS
THE LARGEST SOURCE OF PARTICULATE AIR POLLUTION
(PM) GENERATED AT THE RESIDENTIAL LEVEL. INDEED, IN
SOME LOCALITIES, FIREPLACES AND WOODSTOVES HAVE
BEEN IDENTIFIED AS THE SOURCE OF 80% OR MORE OF ALL
AMBIENT PARTICLES SMALLER THAN 2.5 MICRONS IN
MONTHS. A LARGE BODY OF EVIDENCE LINKS PM WITH
ADVERSE HEALTH OUTCOMES, INCLUDING EXCESS
CARDIOPULMONARY ILLNESS.
FIREPLACES AND WOODSTOVES, AND EVEN SPECIAL
EQUIPMENT SUCH AS WOOD PELLET COMBUSTORS AND
EPA PHASE II CERTIFIED WOODSTOVES -- AS
DESIGNED -- PRODUCE ORDERS OF MAGNITUDE MORE
PM THAN WELL-TUNED OIL OR GAS DEVICES PRODUCING
EQUIVALENT HEAT.
MOREOVER, WOODSTOVES ROUTINELY PRODUCE SEVERAL
TIMES MORE AIR POLLUTANTS THAN ORIGINAL DESIGN
VALUES SIMPLY BECAUSE OF IMPROPER OPERATION
(INCLUDING THEIR MISUSE AS INCINERATORS FOR
RESIDENTIAL REFUSE), MAINTENANCE, AND NORMAL
EQUIPMENT DEGRADATION WITH USE. ACCORDING TO
THE U. S. DEPARTMENT OF ENERGY, WOODSTOVES WERE USED TO BURN
OVER 70 PERCENT OF THE 34 MILLION TONS OF RESIDENTIAL WOOD COMBUSTED
IN 1990.
MORE THAN 90% OF THE WOODSMOKE PARTICLE MASS
CONSISTS OF FINE PARTICLES, THE FRACTION OF PM
THAT MANY RESEARCHERS CONSIDER TO HAVE THE
GREATEST ASSOCIATION WITH ADVERSE HEALTH
OUTCOMES. IN ADDITION TO FINE PM, WOODSMOKE
EMISSIONS CONTAIN COMPONENTS SUCH AS CARBON
MONOXIDE (AN ASPHYXIANT), VARIOUS IRRITANT GASES
SUCH AS NITROGEN DIOXIDE, SULFUR DIOXIDE,
HYDROCHLORIC ACID, AND ALDEHYDES SUCH AS
FORMALDEHYDE AND ACROLEIN, AND CHEMICALS
KNOWN OR SUSPECTED TO BE CARCINOGENS, SUCH AS
POLYCYCLIC AROMATIC HYDROCARBONS (PAHs),
OXYGENATED PAHs, AND POLYCHLORINATED DIOXINS AND
FURANS.
REAL-TIME MONITORING OF AIRBORNE PARTICULATE
MATTER AND PAH LEVELS IN MANY RESIDENTIAL AREAS
ACROSS THE COUNTRY SHOWS THAT EXPOSURE TO
THESE POLLUTANTS IN SUCH AREAS IS CONSISTENT
WITH THE TEMPORAL PATTERN OF RESIDENTIAL WOOD
COMBUSTION. THE SITES STUDIED ARE REMOTE FROM
INDUSTRIAL SOURCES AND THE TIMES OF MAXIMUM
POLLUTANT LEVELS DO NOT CORRELATE WITH LOCAL
TRAFFIC ACTIVITY.
OUTDOOR PAH LEVELS IN SUCH RESIDENTIAL AREAS HAVE
REACHED 2 MICROGRAMS PER CUBIC METER DURING
HOLIDAY EVENINGS -- COMPARABLE TO THE MAXIMUM
RECORDED PAH CONCENTRATIONS IN SECONDHAND
TOBACCO SMOKE. ACCORDING TO THE U. S. EPA, 29
PERCENT OF ALL PAHs EMITTED IN THE U. S. ORIGINATE
FROM RESIDENTIAL WOOD COMBUSTION, AND
CONVENTIONAL WOODSTOVES CAN EMIT UP TO 20 TIMES
AS MUCH PAHs AS EMITTED BY FIREPLACES, PER POUND
OF WOOD BURNED.
THERE ARE NUMEROUS AREAS IN WHICH OUTDOOR PM10
LEVELS, DUE PRIMARILY TO WOODSMOKE EMISSIONS,
HAVE EXCEEDED THE FEDERAL 24-HOUR STANDARD OF 150
MICROGRAMS PER CUBIC METER, WELL ABOVE THE
THRESHOLD FOR OBSERVED HEALTH EFFECTS.
STUDIES HAVE ALSO SHOWN THAT PEOPLE USING WOOD
BURNING DEVICES TO HEAT THEIR HOMES CAN BE
ROUTINELY EXPOSED TO EXCESSIVE LEVELS OF FINE PARTICULATE MATTER
THAT ARE RELEASED FROM THESE
DEVICES INTO THEIR INDOOR AIR. IN CASES WHERE SUCH
OPERATION IS CONTINUOUS, THE FEDERAL PM2.5 24-HOUR
STANDARD OF 65 MICROGRAMS PER CUBIC METER COULD
UNDER CERTAIN CIRCUMSTANCES BE EXCEEDED.
MOREOVER, MONITORING OF THESE SAME POLLUTANTS
IN INDOOR ENVIRONMENTS OF NEARBY (NONSMOKING,
NON-WOODBURNING) HOMES HAS SHOWN LOWER YET
STILL SIGNIFICANT CONCENTRATIONS (MORE THAN
HALF OF OUTDOOR LEVELS), LAGGING IN TIME BEHIND
OUTDOOR PEAKS. THUS, THOSE WHO USE A WOODSTOVE
TO HEAT THEIR HOME ARE LIKELY EXPOSING THEIR
COMMUNITIES, AND ESPECIALLY THEIR OWN FAMILIES,
TO GREATER HEALTH RISKS.
FINDINGS FROM ANIMAL TOXICOLOGICAL STUDIES
DEMONSTRATE A REDUCTION IN PULMONARY ANTI-
BACTERIAL DEFENSE MECHANISMS ASSOCIATED WITH
WOODSMOKE EXPOSURE. WOODSMOKE EXPOSURE CAN
DISRUPT CELLULAR MEMBRANES, DEPRESS MACROPHAGE
ACTIVITY, DESTROY CILIATED AND SECRETORY
EPITHELIAL CELLS AND CAUSE ABERRATIONS IN
BIOCHEMICAL ENZYME LEVELS.
EPIDEMIOLOGICAL STUDIES SHOW A COHERENCE OF DATA
AMONG STUDIES OF HEALTH CONSEQUENCES FOR THOSE
EXPOSED TO WOODSMOKE. PERSONS AT HIGHER RISK
INCLUDE YOUNG CHILDREN, THE ELDERLY, AND PEOPLE
WITH PREEXISTING CARDIOPULMONARY DISEASE.
DEMONSTRATED EFFECTS INCLUDE INCREASED
PULMONARY SYMPTOMS, INCREASED HOSPITAL
ADMISSIONS FOR LOWER RESPIRATORY INFECTIONS,
EXACERBATION OF ASTHMA, AND DECREASED
PULMONARY FUNCTION IN SCHOOL-AGE CHILDREN.
AS A MAJOR CONTRIBUTOR TO ATMOSPHERIC PM LOADING,
WOODSMOKE CAN ALSO BE INDIRECTLY LINKED WITH A
VARIETY OF OTHER PM-ASSOCIATED OUTCOMES, INCLUDING INCREASED
RISKS OF SCHOOL ABSENTEEISM, EMERGENCY ROOM VISITS AND HOSPITALIZATIONS
FOR
CARDIOPULMONARY CONDITIONS, AND MORTALITY.
EXPERIENCE SHOWS THAT METEOROLOGIC AND
TOPOGRAPHIC FACTORS AND BACKGROUND AMBIENT AIR
QUALITY MAY AFFECT THE SERIOUSNESS OF THE
IMPACT OF WOODBURNING IN A COMMUNITY ON PUBLIC
HEALTH. WHAT MAY BE CONSIDERED ACCEPTABLE
PREVALENCE AND PROXIMITY OF RESIDENTIAL WOODCOMBUSTION IN ONE
AREA MAY NOT NECESSARILY
BE SO IN ANOTHER.
FINAL NOTE 1:
PRACTICES SUCH AS OPEN BURNING OF HOUSEHOLD
REFUSE AND YARD WASTES ALSO PRODUCE GROSS
EMISSIONS OF PRODUCTS OF INCOMPLETE COMBUSTION. EXPOSURE TO THESE
EMISSIONS HAS BEEN LINKED WITH ACUTE SYMPTOMS AND ADVERSE
HEALTH EFFECTS. WHILE ADDITIONAL STUDY TO CHARACTERIZE THESE
EMISSIONS AND EFFECTS IS CLEARLY NEEDED, ALA EXPRESSES A PREFERENCE
FOR CONSERVATIVE PUBLIC HEALTH POLICIES THAT DISCOURAGE SUCH
OPEN BURNING, ESPECIALLY
WHERE THE POTENTIAL FOR SIGNIFICANT EXPOSURE OF VULNERABLE POPULATIONS
TO THE RESULTING EMISSIONS EXISTS.
FINAL NOTE 2:
FOR CONSUMERS WHO ARE CONSIDERING REPLACING
THEIR WOOD BURNING APPLIANCES WITH GAS BURNING
APPLIANCES, ALA RECOMMENDS CHOOSING VENTED
APPLIANCES WHENEVER POSSIBLE, TO MINIMIZE POTENTIAL INDOOR AIR
QUALITY CONCERNS.