Energy Insecurity Influences Urban Outdoor Air Pollution Levels during COVID-19 Lockdown in South-Central Chile

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Abstract
Introduction: In south-central Chile, outdoor air pollution primarily originates as household air pollution from wood burning for heating. The effect of COVID-19 lockdowns on ambient air pollution levels in urban south-central Chile may therefore be different from trends observed in cities where transportation and industrial emission sources dominate.Methods: This quasi-experimental study compares hourly fine (PM2.5) and coarse (PM10) particulate matter measurements from six air monitoring stations (three reference grade beta attenuation monitors and three low-cost SPS30 sensors) in commercial and low or middle-income residential areas of Temuco and Padre Las Casas, Chile between March-September 2019 and 2020 (spanning COVID-19 lockdown).Results: In Padre Las Casas, average outdoor PM2.5 concentrations peaked above 100 ug/m3 from 8-10 pm during winter (May-August) 2019 and 2020, when wood burning is common. During COVID-19 lockdown, average monthly ambient PM2.5 concentrations in a commercial and middle-income residential area of Temuco were up to 50% higher (12 µg/m3 to 18 µg/m3) and 59% higher (22 µg/m3 to 35 µg/m3) than 2019 levels, respectively. Conversely, PM2.5 levels decreased by up to 52% (43 µg/m3 to 21 µg/m3) in low-income neighborhoods. The night-time (8 pm-9 am) mass percent of PM10 that was PM2.5 during strict quarantine (April 2020) increased by 48% above April 2017-2019 proportions (50% to 74%) in a commercial area of Temuco.Conclusions: Wood burning for home heating was responsible for a significantly higher proportion of ambient PM2.5 pollution in commercial areas and middle-income neighborhoods of Temuco during COVID-19 lockdown, compared to winter months in 2019. Constrastingly, energy insecure households likely refrained from wood heating during lockdown, leading to PM2.5 concentration declines. To reduce the double burden of ambient air pollution and energy insecurity in south-central Chile, affordability of clean heating fuels (e.g. electricity, liquefied petroleum gas) should be a policy priority.
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