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A massive pile of wood debris caught fire and burned from October 27 to October 31, 2001, innorthern Pinal County, Arizona. The fire consumed wood debris from citrus trees that had beenstored in an approximately 25-acre area in Pinal County near the Queen Creek area. The pile ofwood debris was approximately 5 feet deep.

The fire generated a large quantity of smoke. Persons reported smelling the smoke up to 40miles away from the fire. Meteorological conditions during the fire intermittently createdconditions that limited lift, especially at night, causing smoke to settle in residentialneighborhoods in the Queen Creek area. The Arizona Department of Health Services issuedpublic health advisories for the evenings of October 29 and 30.

This report summarizes the events that occurred during the fire and analyzes the data collectedby the Arizona Department of Health Services and the Arizona Department of EnvironmentalQuality to determine the extent of the public health threat from the fire.


The fire began on the morning of October 27, 2001, at a wood debris storage area on vacant landlocated south of Empire Blvd and east of Ellsworth Road in Queen Creek, Arizona. The fireconsisted of burning debris from citrus trees that had been stored in an approximately 25-acrearea at the site. The pile of wood debris was approximately 200 yards wide, 400 yards long, and5 feet deep.

The Rural Metro Fire Department responded to the fire around noon on October 27, 2001. Thefirefighters decided that the best strategy was to watch the fire burn itself out and to prevent itfrom spreading to other areas.

At 8:00 am, on October 29, staff from the Arizona Department of Health Services and theArizona Department of Environmental Quality began receiving calls from citizens complainingabout the smoke. A hazardous materials officer from the Arizona Department of EnvironmentalQuality and staff from the Arizona Department of Health Services arrived at the scene in themorning. A large quantity of smoke was seen rising from the wood, shifting directions, andintermittently settling in nearby neighborhoods.

The Rural Metro Fire Department conceded that the fire was overwhelming their resources atapproximately 10 a.m. on October 29. Pinal County then took responsibility for fighting the fireand added additional resources in an attempt to extinguish the fire.

As a result of the levels of respirable particulate matter (PM10) measured and the expectationthat there would be higher particulate levels during the evening, the Arizona Department ofHealth Services issued a health advisory for the Queen Creek area for October 29. The mediarelease recommended that persons remain indoors during the night and shut their windows. Persons with respiratory problems in the Queen Creek area were urged to see their physicians ifthey had symptoms. It also suggested that those with respiratory problems in the smoky areashould consider finding an alternative place to sleep.

ADHS staff contacted local schools to communicate health risks, provide safety advice andassess the public health impact of the fire. Contact was made with the Queen Creek SchoolDistrict, Ben Franklin Charter School, the Florence School District, the Higley School Districtand the Chandler School District. School personnel were advised to keep children inside whensmoke was present. School personnel reported complaints of haze and odor. Some childrenwith asthma were reportedly sent home.

The firefighting efforts continued into the morning of October 30 with some success. However,additional resources were needed, and that afternoon the Arizona State Land Department, at therequest of the Governor, brought more firefighters and resources to fight the fire. Whilesignificant progress had been made putting out the fire by the afternoon, there was sufficientsmoke in the area. Therefore, the Arizona Department of Health Services to declared anotherpublic health advisory for the evening of October 30. The American Red Cross of Arizonaactivated a shelter for people being impacted by the smoke on Tuesday night, but nobody wentthere for assistance.

The firefighters worked throughout the night and by the morning of October 31, approximately60 % of the fire had been contained. It was officially extinguished at 3:30 p.m. on October 31.


This public health evaluation was prepared using PM-10 air sampling data collected by theArizona Department of Environmental Quality and observations made by Arizona Department ofHealth Services staff during the event.

This report evaluates environmental sampling data by comparing the PM-10 analytical results toestablished screening levels and data in the scientific literature to determine the magnitude of thepublic health threat from the fire. The primary screening values used to evaluate the particulatematter were the United States Environmental Protection Agency Ambient Air Quality Standardsand Emergency Episode Levels and the World Health Organization Health Guidelines forVegetation Fire Episodes.1


The Arizona Department of Environmental Quality, Hazardous Air Response Team arrived atthe scene at approximately noon on October 29. The team set up monitors to quantify respirableparticulate matter (PM-10) levels at several locations in the area. Afternoon PM-10 readings inresidential areas 1 mile from the fire ranged from 70 micrograms per cubic meter (µg/m3) to 176 µg/m3.

Daytime transient PM-10 levels were exceeding the United States Environmental ProtectionAgency 24 hour standard for PM-10 of 150 µg/m3 and the World Health Organization HealthGuidelines for Vegetation Fire Episodes. Meteorologists at the scene suggested that theyexpected winds to calm in the evening, increasing PM-10 levels in the neighborhoods within a 3-mile area of the fire.

Consistent with the meteorological predictions, smoke from the fire settled in neighborhoods inthe Queen Creek area during the evening of October 29. The sampling team observed that PM-10 concentrations frequently changed by several hundred ug/m3 within minutes. A reading in theOrchard Lane neighborhood (located about one-half to three-fourths of a mile north of the fire)at 12:30 am was 70 µg/m3. The concentration at the same location 15 minutes later was 251 µg/m3. Readings along Achilles Way ranged from 348 µg/m3 to 418 µg/m3 in a five-minuteperiod at approximately 12:50 am. Readings at the corner of Achilles Way and EmpireBoulevard ranged from 1,698 µg/m3 to 2,156 µg/m3 in a 5-minute span at approximately 1:10am. PM-10 concentrations in these ranges were consistent throughout the night.

The concentrations of PM-10 in the neighborhoods near the fire fell as wind picked up andatmospheric mixing increased on the morning of October 30. PM-10 concentrations in QueenCreek were generally in the 100 to 200 µg/m3 range throughout the day on October 30.

Queen Creek PM-10 Levels - October 29th and 30th, 2001

  Measured PM-10 Range
(µg/m3 )
24-Hour USEPA Standard
(µg/m3 )
24-Hour USEPA Alert
(µg/m3 )
1-Hour WHO Alert Stage Guideline
(µg/m3 )
Transient Daytime PM-10 70 - 176 150 350 400
Transient Nighttime PM-10 70 - 2,156 150 350 400


Wood smoke is a complex mixture of substances produced during the burning of wood. Themajor emissions from burning wood are particulate matter, carbon monoxide, and organic gases.Because the particles in wood smoke are too small to be filtered by the nose and upperrespiratory system they wind up deep in the lungs where they can remain for days, potentiallycausing tissue damage and respiratory health effects.

Exposure to wood smoke is well recognized to cause a decrease in lung function. Theoccurrence of respiratory illness in children has been shown to increased with increasedexposure to wood smoke. Symptoms include lower respiratory infections and bronchitis. Woodsmoke also aggravates asthma, emphysema, and bronchitis. It can also irritate the eyes and cantrigger headaches and allergies.

Epidemiological studies have consistently found that prolonged exposure to PM-10 may causeshortness of breath, increases in coughs, aggravation of asthma, decreases in lung function andlung defense mechanisms, chronic obstructive pulmonary disease, and increased rates ofhospitalization for respiratory and cardiovascular illnesses.2-13

Wood smoke containing particulate matter was intermittently present in the residentialneighborhoods within a 3-mile radius of the fire. The concentrations of PM-10 changed byseveral hundred µg/m3 in minutes. Measurements on residential neighborhoods approximately 1mile from the fire at night ranged from 70 µg/m3 to 2,156 µg/m3. Readings in the 200 to 300µg/m3 range were common at night when atmospheric mixing was at a minimum. People in theneighborhoods were generally in their homes during this time.

Particulate matter infiltrates into the indoor air of homes even when doors and windows are shut.The amount of PM-10 infiltrating indoors depends on how air-tight the home is and the averageoutdoor particle concentration. Particle size also influences infiltration rates since largerparticles stick to surfaces more readily than smaller particles. Since average PM-10concentrations are not known, and because of the variability in the infiltration rate of homesdepending on their structure and operation, it is impossible to determine what the concentrationsof particulate matter may have been in area homes during the fire.

The outdoor PM-10 concentrations at night were sufficient to result in a transient decrease inlung function. Plausible symptoms in area residents include cough, other lower respiratorysymptoms, and possibly aggravated asthma symptoms.

The concentration of PM-10 was lower during the day than at night on October 29 and 30,however, human activity and outdoor exposure to the particulate matter increased during the day.These factors increase exposure and the potential for health effects.

The data collected during the investigation suggest that the smoke likely caused an increase inrespiratory problems in some area residents of Queen Creek consistent with wood smokeinhalation, suggesting that the fire represented an acute (short-term) public health hazard.


ATSDR's Child Health Initiative recognizes that the unique vulnerabilities of infants andchildren demand special emphasis in communities faced with contaminants in air. Children are more likely to be exposed because they play outdoors. Their developing body systems ofchildren can sustain permanent damage if toxic exposures occur during critical growth stages.

Furthermore, children, even those without pre-existing illness or chronic conditions, aresusceptible to air pollution because their lungs are still developing, and they are often engaged invigorous outdoor activities, making them more sensitive to pollution than healthy adults. Studieshave shown that in children, particulate pollution is associated with increased episodes ofcoughing and difficulty breathing, and decreased lung function.

Children, particularly those with asthma, were likely among the most affected persons during thewood debris fire.


The ADHS finds that the smoke likely caused an increase in respiratory problems in some QueenCreek area residents, consistent with wood smoke inhalation, suggesting that the fire representedan acute (short-term) public health hazard.


No further recommendations are indicated at this time.


Arizona Department of Health Services, Office of Environmental Health

Will Humble, Chief, Office of Environmental Health, Principal Investigator

ATSDR Regional Representative

William Nelson
Office of Regional Operations, Region IX
Office of the Assistant Administrator

ATSDR Technical Project Officer

Gail Godfrey
Division of Health Assessment and Consultation
Superfund Site Assessment Branch
State Programs Section


  1. Johnson RA. 1998. Guidance on Measures for Vegetation Fire Episodic Events. WorldHealth Organization, Lima, Peru. October 1998.

  2. Pope, C.A., 1991. Respiratory Hospital Admissions Associated with PM10 Pollution inUtah, Salt Lake and Cache Valleys. Arch. Environ. Health. 46:90-97.

  3. Pope, C.A., Dockery, D. 1992. Acute Health Effects of PM10 Pollution on Symptomaticand Asymptomatic Children. Am. Rev. Respir. Dis. 145:1123-1128.

  4. Schwartz, J., Slater, D. etal. 1993. Particulate Air Pollution and Hospital EmergencyRoom Visits for Asthma in Seattle. Am. Rev. Respir. Dis. 147:826-831.

  5. Dockery, D., Pope, C. 1994. Acute Respiratory Effects of Particulate Air Pollution. Annual Review of Public Health.15:107-32

  6. Dockery, D., Pope, A., etal. 1993. An Association Between Air Pollution and Mortalityin Six U.S. Cities. New England Journal of Medicine. December 9, 1993. Vol.329:24 p.1753-1759.

  7. Pope, C.A., Schwartz, J. 1992. Daily Mortality and PM10 Pollution in Utah Valley. Arch. Environ. Health. 47:211-217.

  8. Schwartz, J., Dockery, D. 1992. Increased Mortality in Philadelphia Associated withDaily Air Pollution Concentrations. Am. Rev. Respir. Dis. 145:600-604.

  9. Schwartz, J., Dockery, D. 1992. Particulate Air Pollution and Daily Mortality inSteubenville, Ohio. American Journal of Epidemiology. 135:12-23.

  10. Pope, C. A., Thun, M. 1995. Particulate Air Pollution as a Predictor of Mortality in aProspective Study of U.S. Adults. Am. J. Respir. Crit. Care Med., Vol 151. pp 669-674.

  11. Arizona Department of Environmental Quality. 1995. Arizona ComparativeEnvironmental Risk Project, Human Health Technical Committee Final Report. August, 1995. pp 107-115.

  12. Arizona Department of Environmental Quality. 1992. 1991 Air Quality Control forArizona. Office of Air Quality. November, 1992.

  13. Dockery, D. 1981. Indoor-Outdoor Relationships of Respirable Sulfates and Particulates. Atmos. Environ. 15:335-343.


This Wood Debris Fire Health Consultation was prepared by the Arizona Department of HealthServices under cooperative agreement with the Agency for Toxic Substances and DiseaseRegistry. It is in accordance with approved methodology and procedures existing at the time thehealth consultation was initiated.

Gail D. Godfrey
Technical Project Officer

The Division of Health Assessment and Consultation (DHAC), ATSDR, has reviewed this health consultation and concurs with its findings.

Sven E. Rodenbeck
for Richard Gillig


Click here to view Appendix A in PDF format (PDF, 38KB)

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