Oregon Wildfire Health Impact Tracked


  • During the 2020 Oregon wildfires, public health analysts used syndromic surveillance to understand the effect of smoke on residents.
  • Syndromic data helped to identify vulnerable populations, indicating a 25% statewide increase in people seeking care for asthma-like illness.
  • Syndromic surveillance data were also used to inform emergency preparedness and risk communication during the wildfires.
Oregon wildfire burning

Public health problem

The 2020 Oregon wildfires were unprecedented. Nine people lost their lives, over 1 million acres burned, and more than 4,000 structures were destroyed. Air quality levels in September were unhealthy in many parts of the state for 12 days or more.

Wildfire smoke is especially dangerous because it can affect geographic areas and populations far outside the burn zone. Smoke from a wildfire not only causes general health problems in those exposed, but it can also worsen chronic respiratory and cardiovascular health conditions. Across Oregon, the air quality became increasingly unhealthy, triggering health alerts and increasing hospital visits.

Actions taken

Public health analysts used syndromic surveillance to monitor air quality and better understand the effect of wildfire smoke on Oregon residents. Syndromic surveillance is an early-detection method that uses electronic health data collected in near real-time when people seek care in hospital emergency departments and urgent care centers. Analysts use syndromic data to understand who is being affected, and how, and to understand the health threat, its spread, and trends. Syndromic surveillance systems allow analysis of syndromic data in combination with other data. Asthma-like illness (syndromic data), for example, can be analyzed with levels of pollutants in the air during the wildfires.

Oregon’s public health analysts used the state’s syndromic surveillance system, OR–ESSENCE (Figure 1), to collect electronic health data. They used these data to monitor the effects of the wildfire on the public’s health and the burden being placed on health care facilities. By combining syndromic data with other data sources, the analysts could characterize asthma-like illness (ALI) during a period of high pollution (fine particulate matter: PM2.5) from the Oregon wildfires. They analyzed ALI emergency department and urgent care visits and PM2.5 air quality data from OR–ESSENCE statewide and by county, summarizing ALI visits and 24-hour average PM2.5 for a 4-week period from Sept. 6, 2020, through Oct. 3, 2020. Once they identified unhealthy air quality levels across large areas of the state during the “wildfire” period, the analysts could compare these data with the preceding 4-week “reference” period. ALI visits were stratified statewide by race and ethnicity.

Location of facilities contributing syndromic data
Figure 1. Location of facilities contributing syndromic data used for evaluation of asthma-like illness during September 2020 wildfires in Oregon.


Syndromic surveillance gave Oregon the capacity needed to better monitor not only the devasting impact of the wildfires on the public's health, but also the burden being placed on health care resources.

The use of syndromic surveillance helped to identify vulnerable populations. ALI visits among Hispanic or Latino populations in Oregon were 30.0% higher during wildfires compared to 22.4% higher for non-Hispanic or Latino populations during the same period. The statewide overall increase (not stratified by ethnicity) was 24.9%.

ALI statewide rates were elevated by 2.2 daily visits per 100,000 population during the wildfires. Changes in daily visit rates per 100,000 during the wildfires by race were:

  • Black or African American, +1.2 daily visits (+10.0%)
  • American Indian/Alaska Natives, +0.9 daily visits (+9.1%)
  • Asian, +0.3 daily visits (+7%)

(The Native Hawaiian/Pacific Islander group had no change in daily visits during the wildfires compared to the reference period.)

Statewide 24-hour average PM2.5 measured 63.5 micrograms per cubic meter (ug/m3) during the wildfire period compared with 7.7 ug/m3 for the reference period, which is an increase of 765% (Figure 2). PM2.5 was elevated during the wildfires for 29 of 36 counties for which PM2.5-monitored data are available. County increases in 24-hour average PM2.5 during the wildfires ranged from 44% to 2,652%.

Graph showing how statewide emergency department visits tracked with particulate matter in the air as a result of wildfires in August and September 2020
Figure 2. Emergency department asthma-like visits from near real-time syndromic surveillance (OR–ESSENCE) and daily statewide maximum PM2.5 (ug/m3) particulate matter in Oregon from August–September 2020.

Syndromic surveillance data were also used to inform emergency preparedness and risk communication during the wildfires. Syndromic data not only benefitted Oregon's understanding and mitigation of the wildfires, but the versatility of syndromic surveillance makes it a valuable tool in the identification, characterization, monitoring, and response to other public health threats as well.


Carol A. Trenga, MS, PhD
Oregon Health AuthorityPublic Health Division
Environmental Public Health

Centers for Disease Control and Prevention
Office of Public Health Data, Surveillance, and Technology Detect and Monitor Division

The findings and outcomes described in this syndromic success story are those of the authors and do not necessarily represent the official position of the National Syndromic Surveillance Program or the Centers for Disease Control and Prevention.