Increasing wildfire smoke has limited impacts on national park visitation in the American West

Abstract

Ambient wildfire smoke in the American West has worsened considerably in recent decades, while the number of individuals recreating outdoors has simultaneously surged. Wildfire smoke poses a serious risk to human health, especially during long periods of exposure and during exercise. As such, evaluating whether people modify recreation in response to smoke is important to understanding the public health implications of these trends. Here we aggregate data on black carbon, a major component of wildfire smoke, and recreational visitation in 32 US national parks from 1980 to 2019 to examine how visitors respond to wildfire smoke. We hypothesize that visitor response may exhibit a threshold effect where ambient smoke reduces visitation after a critical level, but not before. We develop a series of breakpoint models to test this hypothesis. The results of these models are mixed, but overall show little to no effect of ambient smoke on visitation to the 32 parks tested, even when allowing for critical thresholds at the extreme upper ranges of smoke exposure. This indicates that wildfire smoke does not greatly alter park attendance. This finding suggests that management actions to protect visitor health during smoke events may be warranted.

Decreased air quality shows minimal influence on peak summer attendance at forested Pacific West national parks

“…Our findings augment that of other recent studies utilizing large scale remotely sensed data through increased spatial granularity and in-situ data (Clark et al, 2023). We echo their recommendation to limit visitor access reflecting air quality conditions.…”

“…Researchers have identified air quality and its potential influences on visitation within the greater context of climate change as a specific gap in the literature (Rutty et al, 2022). Clark et al (2023) specifically assessed the impacts of remotely sensed black carbon on visitor attendance. They found no decrease in attendance, but one of the key limitations of their study was the coarse spatial resolution of the black carbon data they utilized and whether or not it reflected surface level air quality accurately.…”

Visitation to national parks in California shows annual and seasonal change during extreme drought and wet years

“…However, for the Park Service, many wildland fires are left to burn for forest resource benefit so long as they remain in wilderness. Outside closures that result from fires which threaten property and life, visitation to parks remains generally persistent during the peak season, including during times of poor and unhealthy air quality from wildfire smoke [63]. Otherwise, mountain parks and the more visited arid and coastal parks appear to be the relatively most immune to visitation fluctuations throughout the year, while parks that are typically very dry (i.e., Channel Islands, Death Valley) or susceptible to seasonal precipitation and flooding (i.e., Redwood, Pinnacles) exhibit the greatest variability between extreme drought or wet conditions, among other categories.…”