No abstract

Several authors have demonstrated improvements in the mechanical performance of asphalt mixes by including the use of fibers. However, it has also been reported that environmental assessments must address fiber use in asphalt mixes from the point of view of sustainability. In this study, a life cycle assessment is used to compare the use of four different fibers (fiberglass, polyester fiber, aramid fiber, and cellulose fiber) commonly used in hot mix asphalt (HMA) and stone mastic asphalt (SMA) mixes. Additionally, the use of textile fibers from end-of-life tires (FiTyre) is included in the comparison. The results show that in the five selected impact categories (climate change, terrestrial acidification, human toxicity, particulate matter emissions, and the exhaustion of nonrenewable fossil fuels), the use of FiTyre and cellulose fibers is more advantageous than existing traditional fibers (fiberglass, polyester fiber, and aramid fiber).

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 ug/m3 to 18 ug/m3) and 59% higher (22 ug/m3 to 35 ug/m3) than 2019 levels, respectively. Conversely, PM2.5 levels decreased by up to 52% (43 ug/m3 to 21 ug/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.