Transport of Non-Methane Hydrocarbons and Their Impact on the Air Quality in Quintero, a Small Coastal City in Chile

Quintero is a Chilean coastal city located 40 km north of Valparaiso. In the surroundings of Quintero, there are a number of industries that generate high levels of atmospheric pollutants such as sulfur dioxide (SO2), nitrogen oxides (NOx), carbon monoxide (CO) and non-methane hydrocarbons (NMHCs). These compounds may also be generated during oil handling in storage facilities in this area. Quintero Bay has a port that is being used mainly for oil and copper transportation. Since 2010, there have been reports of events producing nausea, vomiting and abdominal pain in the residents of Quintero, and some previous studies have correlated these medical events with high concentrations of SO2 and NMHCs. One of the main sources of SO2 in the area was identified to be the Ventanas copper foundry. Following public pressure, the government stopped the operation of the foundry by mid-2023, which led to a significant decrease in SO2 levels. However, reports of health problems persisted to some extent. In this work, delayed cross-correlation, trajectory and dispersion analyses indicate that an upwind source of air pollution impacting Quintero originates near the oil refinery in Concón, located 20 km to the south. This source of air pollution could provide a background of NMHCs, over which local emissions add up to attain very high concentrations in Quintero. Our analysis shows that there is evidence of the transport of NMHCs from the Concón refinery to the Quintero area. In 2022, of the 20 days with NMHC concentrations greater than 200 ppvb, 50% of them were associated with prevalent southwest winds. Using trajectory and dispersion analyses for eight episodes in Quintero, it has been found that an approximate fraction of pollution generated in Concón that could arrive in Quintero is between 2 and 24%.