Abstract
Among the hazards posed by volcanoes are the emissions of gases and particles that can affect air quality and damage agriculture and infrastructure. A recent intense episode of volcanic degassing associated with severe impacts on air quality accompanied the 2018 lower East Rift Zone (LERZ) eruption of Kīlauea volcano, Hawai'i. This resulted in a major increase in gas emission rates with respect to usual emission values for this volcano, along with a shift in the source of the dominant plume to a populated area on the lower flank of the volcano. This led to reduced air quality in downwind communities. We analyse open-access data from the permanent air quality monitoring networks operated by the Hawai'i Department of Health (HDOH) and National Park Service (NPS), and report on measurements of atmospheric sulfur dioxide (SO2) between 2007 and 2018 and PM2.5 (aerosol particulate matter with diameter <2.5 μm) between 2010 and 2018. Additional air quality data were collected through a community-operated network of low-cost PM2.5 sensors during the 2018 LERZ eruption. From 2007 to 2018 the two most significant escalations in Kīlauea's volcanic emissions were: the summit eruption that began in 2008 (Kīlauea emissions averaged 5–6 kt/day SO2 from 2008 until summit activity decreased in May 2018) and the LERZ eruption in 2018 when SO2 emission rates reached a monthly average of 200 kt/day during June. In this paper we focus on characterizing the airborne pollutants arising from the 2018 LERZ eruption and the spatial distribution and severity of volcanic air pollution events across the Island of Hawai'i. The LERZ eruption caused the most frequent and severe exceedances of the Environmental Protection Agency (EPA) PM2.5 air quality threshold (35 μg/m3 as a daily average) in Hawai'i in the period 2010–2018. In Kona, for example, the maximum 24-h-mean mass concentration of PM2.5 was recorded as 59 μg/m3 on the twenty-ninth of May 2018, which was one of eight recorded exceedances of the EPA air quality threshold during the 2018 LERZ eruption, where there had been no exceedances in the previous 8 years as measured by the HDOH and NPS networks. SO2 air pollution during the LERZ eruption was most severe in communities in the south and west of the island, as measured by selected HDOH and NPS stations in this study, with a maximum 24-h-mean mass concentration of 728 μg/m3 recorded in Ocean View (100 km west of the LERZ emission source) in May 2018. Data from the low-cost sensor network correlated well with data from the HDOH PM2.5 instruments, confirming that these low-cost sensors provide a robust means to augment reference-grade instrument networks.
Highlights
Volcanic clouds are complex, evolving mixtures of volcanic and atmospheric gases, primary and secondary aerosol particles, ash and dust (Oppenheimer and McGonigle, 2004; Pfeffer et al, 2006b; von Glasow et al, 2009; Oppenheimer et al, 2010; Langmann, 2014)
We demonstrate that SO2 and PM2.5 mass concentrations during the 2018 lower East Rift Zone (LERZ) eruption in selected communities around the island were of a higher magnitude than during volcanic activity from Kılauea during 2007 to 2017
Western Region: Kona During 2007–2017, the west-coast city of Kailua-Kona was commonly exposed to low mass concentrations of SO2, with a maximum recorded 24-h-mean mass concentration of 79 μg/m3 recorded at the Kona Hawai’i Department of Health (HDOH) station (Table 1)
Summary
Volcanic clouds are complex, evolving mixtures of volcanic and atmospheric gases, primary and secondary aerosol particles, ash and dust (Oppenheimer and McGonigle, 2004; Pfeffer et al, 2006b; von Glasow et al, 2009; Oppenheimer et al, 2010; Langmann, 2014). As well as the potential for global climatic consequences from explosive or large-scale volcanic emissions, low altitude volcanic clouds can have important impacts on air quality, human and animal health, and the environment on the local to regional scale (Hansell and Oppenheimer, 2004; Barsotti et al, 2010; Mather, 2015; Schmidt et al, 2015; Andronico and Del Carlo, 2016; Tam et al, 2016; Ilyinskaya et al, 2017). Exposure to mass concentrations of 1,310 μg/m3 SO2 for 3 min can induce respiratory attacks in asthmatic individuals (Balmes et al, 1987; ATSDR, 1998). In 2010 the U.S Environmental Protection Agency (EPA) set the National Ambient Air Quality Standard (NAAQS) for SO2 mass concentration exposure limits at 195 μg/m3 as an hourly average (EPA, 2010). The European Commission (EC) air quality standards recommend a SO2 mass concentration threshold of 350 μg/m3 for a 3-h average, and 125 μg/m3 as a daily average (EC, 2018)
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