Effects of Air Pollutants from Wildfires on Downwind Ecosystems: Observations, Knowledge Gaps, and Questions for Assessing Risk

Wildfires have increased in frequency and area burned,
trends expected
to continue with climate change. Among other effects, fires release
pollutants into the atmosphere, representing a risk to human health
and downwind terrestrial and aquatic ecosystems. While human health
risks are well studied, the ecological impacts to downwind ecosystems
are not, and this gap may present a constraint on developing an adequate
assessment of the ecological risks associated with downwind wildfire
exposure. Here, we first screened the scientific literature to assess
general knowledge about pathways and end points of a conceptual model
linking wildfire generated pollutants and other materials to downwind
ecosystems. We found a substantial body of literature on the composition
of wildfire derived pollution and materials in the atmosphere and
subsequent transport, yet little observational or experimental work
on their effects on downwind ecological end points. This dearth of
information raises many questions related to adequately assessing
the ecological risk of downwind exposure, especially given increasing
wildfire trends. To guide future research, we pose eight questions
within the well-established US EPA ecological risk assessment paradigm
that if answered would greatly improve ecological risk assessment
and, ultimately, management strategies needed to reduce potential
wildfire impacts.