Respiratory Health Impacts of Wildfire Particulate Emissions Under Climate Change Scenarios

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Project Overview


MODIS satellite imagery of October 2007 wildfire smoke being pushed over the Pacific Ocean via strong Santa Ana winds.

Southern California faces a unique set of challenges heading into the 21st century. Its high urban population density is concentrated along the coast, but is highly proximate to rural areas dominated by fire-driven ecosystems, an area known as the Wildland-Urban Interface (WUI; Radeloff et al. 2005). This large WUI area coupled with a climate phenomena known as the Santa Ana winds make Southern California susceptible to large wildfire disasters (Schroeder et al. 1964, Westerling et al. 2004, Keeley et al. 2004). The Santa Ana Winds create an ideal fire weather environment by exacerbating already-dry conditions and moving hot air at very high speeds through dry shrublands, causing fires ignited in rural areas to be pushed into urban regions of the state. This was exemplified in 2003 and 2007, when large wildfires swept over San Diego County, burning approximately 650,000 acres of grassland and chaparral, killing and injuring several people, and incurring over $3.8 billion in property damages (Karter 2004, Karter 2008). Models of future climate predict weather conditions that will increase the occurrence and severity of wildland fires (Westerling et al. 2006), so it is important to understand how future climate will alter fire regimes and impact public health.

Dr. Nancy French of MTRI headed a study funded by the National Institute of Environmental Health Sciences (, a part of the National Institutes of Health (NIH), to (a) measure and statistically model a relationship between particulate emissions from wildland fires and respiratory illness and then (b) assess the impact of future climatic conditions as manifest in respiratory health outcomes. The study is affiliated with the NIH Climate Change and Health Initiative and funded through the American Recovery and Reinvestment Act (ARRA).

fire figure 1

Events linking human receptors to wildland fire PM emissions with climate feedbacks.

Connecting Wildland Fire PM to Respiratory Health

There are three specific components to the integrated modeling activity: 1) modeling spatially-defined fire emissions, taking into account vegetation fuels and weather, 2) accurately estimating particulate concentrations for downwind regions using transport/dispersion modeling, and 3) combining the smoke emissions with electronic health monitoring to relate the modeled spatial/temporal distribution of pollution to the rates and spatial location of respiratory symptoms. We carried out the development of the predictive model via a Generalized Additive Modeling (GAM) approach, able to incorporate emissions-transport, demographics, weather, and scheduling (day of week) information to derive an accurate predictive relationship for describing the impacts of fire on respiratory health in San Diego County.

Final model results ( ~75% deviance explained) show that at peak fire particulate concentrations the odds of a person seeking emergency care is increased by approximately 50% compared to non-fire conditions.

Workflow for developing the statistical model connecting wildland fire particulate emissions to respiratory health.

Climate Change Effects on Future FireOccurrence and Health Outcomes

Analysis of future fire occurrence shows San Diego County will experience approximately two extreme fire seasons each decade through 2040. We are in the process of finalizing a manuscript to demonstrate the application of the model connecting wildland fire smoke concentration to health outcomes in years of these extreme fire conditions. Our initial results show that the model formulation can be used to assess the location and impact of elevated PM concentrations from particulate emissions originating from wildfire in and around San Diego county that could be valuable for use by public health officials. In a proposed additional grant activity, we hope to work more closely with public health agencies and first responders to better define the value of applying our model and how products we could generate from this study can be improved for their use.

Highlights of Project Outcomes and Results

Our interdisciplinary research team developed a coupled statistical and process-based model system that:

Perimeters of the massive fires that swept across San Diego County in 2003 (blue) and 2007 (red). Inset map shows the larger Southern California study area outlined in pink, with MTBS and MODIS-derived fire perimeters for 2003-2007 shown in multiple colors.

For Additional Information

Nancy French, Ph.D.
Senior Research Scientist

Mike Billmire
Research Scientist

Research Team

Dr. Nancy French, Principal Investigator, Michigan Tech Research Institute (MTRI)
Dr. Brian Thelen, MTRI
Dr. Michele Ginsberg, San Diego County Health & Human Services Agency
Dr. Tatiana Loboda, University of Maryland
Dr. Shiliang Wu, Michigan Technological University
Jeffrey Johnson, San Diego County Health & Human Services Agency
Benjamin Koziol, MTRI
Dr. R. Chris Owen, MTRI
Mike Billmire, MTRI
Yaoxian Huang, MTU
Marlene Tyner, MTRI

Final Progress Report

R code used to fit the statistical model

Project Outputs

Peer-review journal submissions

Hutchinson, Justine A., Jason Vargo, Meredith Milet, Nancy H. F. French, Michael Billmire, Jeffrey Johnson, and Sumi Hoshiko. 2018. "The San Diego 2007 wildfires and Medi-Cal emergency department presentations, inpatient hospitalizations, and outpatient visits: An observational study of smoke exposure periods and a bidirectional case-crossover analysis." PLOS Medicine 15 (7):e1002601. doi: 10.1371/journal.pmed.1002601.

Thelen, B., N. French, B. Koziol, M. Billmire, R. Owen, J. Johnson, M. Ginsberg, T. Loboda, and S. Wu (2013), Modeling acute respiratory illness during the 2007 San Diego wildland fires using a coupled emissions-transport system and generalized additive modeling, Environmental Health, 12(1), 94.

Billmire, M., N.H.F. French, T. Loboda, R.C. Owen, and M. Tyner. “Santa Ana winds and predictors of wildfire progression in southern California.” Submitted to International Journal of Wildland Fire.

Huang, Y., S. Wu, M. K. Dubey, and N. H. F. French (2013), Impact of aging mechanism on model simulated carbonaceous aerosols, Atmospheric Chemistry and Physics, 13(13), 6329-6343, doi:10.5194/acp-13-6329-2013.

Loboda, T., et al. “Modeling Fire Occurrence as a function of Landscape Characteristics: A case study from San Diego county, California” In preparation for submission to Journal of Disaster Risk Reduction.

French, N.H.F., et al. “Wildfire Particulate Emissions and Respiratory Health: Model application and implications under a changing climate”.

In preparation for submission to Environmental Health Perspectives.


NIH Grant#: 1 RC1 ES018612
Project Performance Period: Oct 2009 through July 2012

April 2012: IAWF Human Dimensions of Wildland Fire Seattle, WA N French poster presentation “Respiratory Health Impacts of Wildfire Particulate Emissions under
Climate Change Scenarios”

June 2012: ACCENT-IGAC-GEIA (Global Emissions InitiAtive) Conference Toulouse, France Poster presentation by N. French “Respiratory Health Impacts of Wildfire Particulate Emissions under Climate Change Scenarios”

June 2012: ENVIROMIS 2012 Irutsk, Russia Invited report by T Loboda “The role of satellite observations in assessing impacts of wildfire occurrence on respiratory health of population”

June 2012: NASA Science Meeting, GOFC-GOLD and NEESPI Workshop and Regional Conference Volga, Russia Invited talk by T Loboda “The role of satellite observations in assessing impacts of wildfire occurrence on respiratory health of population”

June 2012: NEHA San Diego, CA Oral presentation by N. French, R.C. Owen, M. Ginsberg, J. Johnson, M. Billmire. “Wildfire Particulate Emissions and Respiratory Health under Climate Change Scenarios: Project overview and results”

December 2011: AGU Fall’11 San Francisco, CA:

June 2011: National Environmental Health Association (NEHA) Columbus, OH, Poster presentation by N. French and B. Koziol. “Respiratory Health Impacts of Wildfire Particulate Emissions under Climate Change Scenarios”

April 2011: American Association of Geographers Seattle, WA Oral presentation by T. Loboda. “Evaluating impacts of climate-driven change in fire regimes on human and natural systems using a Fire Occurrence Model”

December 2010: American Geophysical Union (AGU) Fall’10 San Francisco, CA Poster presentation by B Koziol. “Modeling PM Plumes from 2007 California Wildland Fires using a Coupled Emissions-Transport System”