Simulating PM Concentrations during New Year in Cuenca, Ecuador: Effects of Advancing the Time of Burning Activities.

Fine particulate matter (PM) is dangerous to human health. At midnight on 31 December, in Ecuadorian cities, people burn puppets and fireworks, emitting high amounts of PM. On 1 January 2022, concentrations between 27.3 and 40.6 µg m (maximum mean over 24 h) were measured in Cuenca, an Andean city located in southern Ecuador; these are higher than 15 µg m, the current World Health Organization guideline. We estimated the corresponding PM emissions and used them as an input to the Weather Research and Forecasting with Chemistry (WRF-Chem 3.2) model to simulate the change in PM concentrations, assuming these emissions started at 18:00 LT or 21:00 LT on 31 December 2021. On average, PM concentrations decreased by 51.4% and 33.2%. Similar modeling exercises were completed for 2016 to 2021, providing mean decreases between 21.4% and 61.0% if emissions started at 18:00 LT. Lower mean reductions, between 2.3% and 40.7%, or even local increases, were computed for emissions beginning at 21:00 LT. Reductions occurred through better atmospheric conditions to disperse PM compared to midnight. Advancing the burning time can help reduce the health effects of PM emissions on 31 December.