Health Risk Implications of Volatile Organic Compounds in Wildfire Smoke During the 2019 FIREX‐AQ Campaign and Beyond

Abstract

Fire Influence on Regional to Global Environments and Air Quality was a NOAA/NASA collaborative campaign conducted during the summer of 2019. The objectives included identifying and quantifying wildfire composition, smoke evolution, and climate and health impacts of wildfires and agricultural fires in the United States. Ground based mobile sampling via sorbent tubes occurred at the Nethker and Williams Flats fires (2019) and Chief Timothy and Whitetail Loop fires (2020) in Idaho and Washington. Air samples were analyzed through thermal desorption‐gas chromatography‐mass spectrometry for a variety of volatile organic compounds to elucidate both composition and health impacts. Benzene, toluene, ethylbenzene, xylenes, butenes, phenol, isoprene and pinenes were observed in the wildfire smoke, with benzene ranging from 0.04 to 25 ppbv. Health risk was assessed for each fire by determining sub‐chronic (wildfire event) and projected chronic inhalation risk exposure from benzene, a carcinogen, as well as other non‐carcinogenic compounds including toluene, ethylbenzene, xylenes, and hexane. The cancer risk of benzene from sub‐chronic exposure was 1 extra cancer per million people and ranged from 1 to 19 extra cancers per million people for the projected chronic scenarios, compared to a background level of 1 extra cancer per million people. The hazard index of non‐carcinogenic compounds was less than one for all scenarios and wildfires sampled, which was considered low risk for non‐cancer health events.

Fire Influence on Regional to Global Environments and Air Quality (FIREX‐AQ)

“…In the Nethker fire samples, elevated benzene (a known carcinogen and air toxic) concentrations were seen over 100 times elevated compared to those at McCall, ID which lies 30 miles south. Considering a 30‐day wildfire smoke exposure scenario such as this each year, for 26 years of one's lifetime (average residence in a locale), the risk of cancer goes up by a factor of 19 compared to background (Dickinson et al., 2022). This results in potentially serious human health implications for sub‐chronic to chronic exposure to wildfire smoke, especially with more active and longer duration wildfire seasons in the Northwest.…”

Impacts on Urban VOCs and PM2.5 during a Wildfire Episode

“…Wildfire levels were not statistically higher for carbon disulfide, methacrylonitrile, or cis-1,4-dichloro-2-butene (p > 0.05). Dickinson et al [31] reported increased concentrations of BTEX in ground-level wildfire smoke, with that of benzene ranging from 0.04 to 25 ppbv (0.13 to 79.87 µg/m 3 ). They calculated the ratio of benzene/toluene (B/T) to distinguish wildfire emissions from other emission sources ranging from 0.…”

Fire in the Earth System: Introduction to the Special Collection

“…As part of the 2019 FIREX‐AQ campaign, Dickinson et al. (2022) studied human health‐risk implications from more than 100 volatile organic compounds in the smoke of three different wildfires in Idaho and Washington. They found that the associated benzene exposure could have increased human cancer incidence by as many as 19 cases per million people.…”

“…However, estimating or projecting health impacts (e.g., respiratory-illness hospitalizations, premature deaths, and lost days of work) based on smoke PM 2.5 has substantial uncertainties, as Johnson and Garcia-Menendez (2022) showed for 2016 Southern Appalachian fires: uncertainty in impact estimates due to wildfire smoke spatial fields can be as high as 40%-50%, and greater for some morbidity outcomes (such as asthma hospitalizations). As part of the 2019 FIREX-AQ campaign, Dickinson et al (2022) studied human health-risk implications from more than 100 volatile organic compounds in the smoke of three different wildfires in Idaho and Washington. They found that the associated benzene exposure could have increased human cancer incidence by as many as 19 cases per million people.…”