Mapping pollution exposure and chemistry during an extreme air quality event (the 2018 Kīlauea eruption) using a low-cost sensor network

Abstract

Extreme air quality episodes represent a major threat to human health worldwide but are highly dynamic and exceedingly challenging to monitor. The 2018 Kīlauea Lower East Rift Zone eruption (May to August 2018) blanketed much of Hawai‘i Island in “vog” (volcanic smog), a mixture of primary volcanic sulfur dioxide (SO2) gas and secondary particulate matter (PM). This episode was captured by several monitoring platforms, including a low-cost sensor (LCS) network consisting of 30 nodes designed and deployed specifically to monitor PM and SO2 during the event. Downwind of the eruption, network stations measured peak hourly PM2.5 and SO2 concentrations that exceeded 75 μg m−3 and 1,200 parts per billion (ppb), respectively. The LCS network’s high spatial density enabled highly granular estimates of human exposure to both pollutants during the eruption, which was not possible using preexisting air quality measurements. Because of overlaps in population distribution and plume dynamics, a much larger proportion of the island’s population was exposed to elevated levels of fine PM than to SO2. Additionally, the spatially distributed network was able to resolve the volcanic plume’s chemical evolution downwind of the eruption. Measurements find a mean SO2 conversion time of ∼36 h, demonstrating the ability of distributed LCS networks to observe reaction kinetics and quantify chemical transformations of air pollutants in a real-world setting. This work also highlights the utility of LCS networks for emergency response during extreme episodes to complement existing air quality monitoring approaches.

Assessing the effectiveness of low-cost air quality monitors for identifying volcanic SO2 and PM downwind from Masaya volcano, Nicaragua

“…Similar to this six-month study, in several of the network nodes Craw-ford et al [2021] found SO 2 sensors to experience technical difficulties over the 17-day deployment period. The results from this combined-sensor low-cost network were successful, with similar PM and SO 2 measurements recorded as the regulatory reference-grade network and at a much higher spatial resolution [Crawford et al 2021]. Crawford et al [2021] do not report on the performance of the network over long-term deployment so it is not possible to make a direct comparison with that of the AQMesh network at Masaya.…”

“…Measurement of volcanic SO 2 at sub-ppmv levels has also been demonstrated using electrochemical sensors [Hagan et al 2018;Roberts et al 2018]. In a recent study, networks of low-cost SO 2 and particle sensors have been used to monitor volcanic pollution from the 2018 eruption of Kīlauea (USA) [Crawford et al 2021].…”

Volcanic air pollution and human health: recent advances and future directions

“…This issue has received significant attention recently with the introduction of low-cost fixed networks and hand-held, portable sensors that augment higher accuracy but costly regulatory air quality monitoring. These low-cost PM and SO 2 sensors perform reasonably well for monitoring volcanic air pollution in communities, as demonstrated during the Kīlauea 2018 eruption (Whitty et al 2020;Crawford et al 2021) and in Iceland (Gíslason et al 2015). Air quality forecast models can complement ambient air monitoring and now play an important role in informing the public about current and predicted levels of volcanic pollution in some locations (Barsotti 2020;Holland et al 2020).…”

“…Currently, the utility of low-cost sensors is much greater when they are benchmarked against reference-grade instruments, which may not be available, even regionally. Future improvements in sensor accuracy, calibration, and reliable global satellite internet may contribute to better exposure assessment (Kizel et al 2018;Crawford et al 2021).…”

“…Eruptions may also displace large numbers of people temporarily or permanently (Cuthbertson et al 2020) with cascading health and social impacts including disease outbreaks due to overcrowding, food insecurity, mental health issues, and violence (Connell and Lutkehaus 2017). Airborne volcanic emissions, often referred to as "volcanic air pollution" (Tam et al 2016;Crawford et al 2021), can also present chronic, far-reaching hazards which may have harmful and long-lasting effects on populations across large geographic areas (Oppenheimer et al 2003). Here, we address the state of knowledge regarding volcanic air pollution and health.…”