Wildfire smoke health costs: a methods case study for a Southwestern US ‘mega-fire’

Abstract

Exposure to wildfire smoke can increase morbidity in urban areas. Economists are increasingly calling for such health impacts to be included in wildfire damage assessments. However, collecting original health outcome data is costly and time-consuming. Benefits transfer is a more accessible alternative that is often employed. Yet several methodological issues remain unexplored regarding transfers of economic values and air quality concentration-response functions. Ignoring these issues may lead to misinformed wildfire policy based on inexact estimates of smoke-induced health costs. This research provides a case study illustration of a new air quality benefit transfer tool, the US EPA benefits mapping and analysis program-community edition (BenMAP-CE), which is used to estimate smoke damages of a Southwestern US ‘mega-fire’ event and investigate methodological issues surrounding the analyst's choice between transferring results from ‘wildfire-specific’ and ‘urban air’ (unrelated to wildfire) studies. Results indicate that the economic costs of wildfire smoke are substantial. Additionally, transfer of wildfire-specific study results produces substantially higher morbidity estimates and costs compared to use of results from urban air studies. These findings demonstrate (1) that BenMAP-CE can be applied to wildfire events and (2) the importance of transferred study appropriateness when conducting a smoke damage assessment using benefits transfer.

Keywords:

• wildfire
• benefit transfer
• health effects
• BenMAP-CE
• willingness to pay

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

1. BenMAP-CE is accessible at: http://www2.epa.gov/benmap.

2. As an example of the increasingly common mega-fires seen in recent years in the western USA, the Wallow Fire burned more than 538,000 acres (841 square miles), and is the largest fire on record in Arizona (Ryan and Opperman 2013). The fire covered parts of four counties in eastern Arizona and one in southwestern New Mexico. The fire started near the Bear-Wallow Wilderness Area in the Apache National Forest, and the ignition source was from an unattended campfire. More than 6000 people were evacuated and physical property damages have been estimated to be over $109 million (Ryan and Opperman 2013). While not the source of any known fatalities, the smoke plume extended across New Mexico and into Texas and Oklahoma.

3. Appendix C of the BenMAP User's Manual (Abt Associates 2012) describes the health impact function derivation process, though we note that it's easily performed by-hand.

4. A MRAD is defined as any day on which an individual was forced to alter his or her normal activities due to minor illnesses, including both respiratory and nonrespiratory conditions (Ostro and Rothschild 1989). One shortcoming is that the single MRAD CR function that exists (Ostro and Rothschild 1989) is estimated for urban air quality.

5. Endogeneity was tested for using a Wu-Hausman F-test (p < 0.01) and a Durbin-Wu-Hausman -test (p < 0.01).

6. The inflation-adjusted price reported in Richardson, Champ, and Loomis (2012) of $29.71 (2014$) is used. This result is an average of self-reported prices (including $0). Prices from other sources (e.g., Home Depot, Amazon.com) were investigated and results are available upon request.

7. http://www.epa.gov/airdata/ad_data_daily.html.

8. Results presented in the Table 2 row labelled ‘urban air quality literature’ are estimated by BenMAP-CE using urban air quality CR functions selected by us in the programs’ graphical user interface, which had already been coded into the software by US EPA programmers for the five health endpoints listed. Similarly, results in the row labelled ‘wildfire smoke literature’ are estimated by BenMAP-CE using wildfire-specific CR functions that we manually and individually coded into the program for four of the five incidence endpoints. All individual results in Table 2 are produced by BenMAP-CE calculations.

9. The health endpoint ‘hospital admission: all respiratory’ is comprised of both asthma and pneumonia admissions, in addition to any other respiratory illnesses (not estimated in this analysis). The two endpoints separately illustrate specific drivers of overall respiratory admissions using endpoint-specific CR functions.

Additional information

Funding

This work was supported by the National Science Foundation/New Mexico EPSCOR [grant number EPS-0814449].