Syndromic Surveillance to Monitor Wildfire Events

Primary Topic Areas: 
Public Health Problem (100 words): 

In recent years, Washington State has experienced episodes of degraded air quality from wildfires burning within the state, as well as surrounding states and provinces. Wildfire smoke, particularly the high concentrations of small particulate matter generated by incomplete combustion, can lead to a number of minor as well as significant acute health effects, such as respiratory and cardiac-related issues. As a result, Washington State is developing methodology to monitor syndromic surveillance data for evidence of health impacts across Washington State during ongoing wildfires.

Success Story Narrative (400 words): 

In anticipation of this seasonal event, epidemiologists from Washington State Department of Health sought to develop a myESSENCE dashboard that could be used to monitor air quality across the state and the resulting impacts on human health. An initial draft used patient location as the data source, which allowed for evaluating the impact of wildfire smoke on patients residing in various parts of the state. Emergency department (ED) visits were investigated since these settings are most likely to see patients experiencing a wide range of acute health effects and because data from emergency departments is available for most areas of the state. Topics of interest included PM2.5 concentrations across the state (maximum and average), total ED visit volume, respiratory effects (e.g., general, asthma, bronchitis, Chronic Obstructive Pulmonary Disease, and pneumonia), and cardiovascular effects (e.g., general, Acute Coronary Syndrome, angina, myocardial infarction, and stroke). Additionally, a syndrome was developed to identify visits mentioning wildfires, smoke or smoke exposure. The resulting dashboard contained a number of timeseries widgets to look at trends in air quality across the state, proportion of total ED visits attributable to each syndrome of interest for all ages, as well as sensitive populations (i.e., people ≤5 years of age or ≥65 years of age), and maps to isolate areas of particular concern.

Outcomes And Impact (400 words): 

During the 2018 wildfire season, Washington State experienced 8 days with an average PM2.5 level over 35 μg/m3, the level at which air is considered unhealthy for sensitive populations, with a peak average of 94 μg/m3. The maximum value recorded in Eastern Washington was 389 μg/m3 and Western Washington reached 155 μg/m3. While the concentration and duration of elevated PM2.5 levels varied, nearly every area of the state had at least one day with levels above those considered healthy. Small increases were noted on several days for general respiratory syndromes and asthma, whereas impacts on cardiovascular syndromes were not evident. Queries of patients of all ages appeared to be sufficiently sensitive for situational awareness, but when narrowing to specific age groups, children 0 – 5 appeared to be more sensitive than adults 65 years of age or older.

During week 34 (week starting August 19), 91 emergency department visits were identified that had a mention or diagnosis indicating smoke exposure, as opposed to an average of 11 visits per week during non-wildfire months (i.e., December 2017 – July 2018). This peak in smoke-related visits coincided with the week in which the peak PM2.5 values were also recorded in Washington State (Figure 1).

The dashboard was shared as a managed tab with other epidemiologists within the Department of Health as well as public health practitioners at local health departments to allow for local surveillance. The myESSENCE tab was used to generate a daily update on health impacts from high concentrations of PM2.5. The dashboard also provided information needed for epidemiologists to respond to media inquiries regarding affected populations, assess patterns in health issues and healthcare use, as well as evaluate the necessity for additional public health messaging.

Lessons Learned (400 words): 

In the midst of the wildfire season, the dashboard was refined to include additional graphics that we found ourselves generating as part of the daily review and unnecessary visualizations were removed. For example, timeseries of daily visit counts were converted to visit percent in order to remove the appearance of increases in visit counts that were mostly due to concurrent facility onboarding efforts. We also converted from daily timeseries to weekly timeseries to assess whether such aggregation would amplify the signal we saw, but instead, impacts were marginally noticeable.

In addition to monitoring statewide trends through timeseries visualizations, we attempted to use maps to identify counties most impacted by degraded air quality. Unfortunately, map alerts were not functioning during the 2018 wildfire season and it is currently not possible to visualize air quality information on a map to quickly identify areas likely to experience the highest levels of exposure. As a result, maps provided limited additional insights in the 2018 wildfire season. Instead, micrographs of PM2.5 values measured at each air quality station across the state were used to identify areas that were likely to be impacted by reduced air quality.

We hypothesized that many health impacts due to wildfire smoke exposures would be relatively minor and would not necessitate a visit to an emergency department. As a result, we explored visit trends for each of the syndromes in urgent care settings, but found little, if any, signal for any of the syndromes of interest. This work may be repeated as we bring on additional urgent care clinics, as it’s possible our limited coverage of urgent care clinics at the time may have contributed to this outcome.

While the specificity of the smoke exposure syndrome was poor outside of the main 2018 wildfire smoke event, it performed well when PM2.5 concentrations were increased due to smoke. Mentions of smoke exposure or wildfire can be a useful assessment of the impact of poor air quality in a community. Large increases in the number of emergency department visits mentioning smoke indicate that decision-makers should keep healthcare infrastructure in mind during major smoke events.

The Washington State Department of Health plans to continue use of this dashboard in future fire seasons. Future efforts will include development of a streamlined myESSENCE dashboard for more efficient daily monitoring, and developing separate dashboards for Eastern and Western Washington, our most common geographic breakdown of the State.

Submitting Author Name: 
Rapid Health Informatiom NetwOrk (RHINO)
Submitting Author Organization: 
Washington State Department of Health

December 05, 2018

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