Short-term air pollution events in the Atacama desert, Chile

An evaluation of the concentrations of PM₁₀, PM_2.5, SO₂, CO, NO₂, O₃ and meteorological variables recorded between 2013 and 2016 at three continuous monitoring stations in the urban area of Calama (located in the hyper-arid desert from the Atacama) is presented. The results indicated that the recorded concentrations of PM₁₀, PM_2.5, and SO₂ exceeded the World Health Organization (WHO) daily and annual guidelines throughout the years studied. The diurnal variability of PM₁₀ and PM_2.5 concentrations showed that two maxima occurred during mornings and nights, while SO₂ concentrations showed a single acute maximum at noon. The relationship between the wind regime in the area and the concentrations of PM₁₀ and PM_2.5 implied significant contributions from sources located at the west end of the city: industrial sources (local mining industry) and natural sources (the Atacama desert) during warmer seasons, while local urban sources (vehicles and residential heating) became more relevant during cooler seasons. Maximum SO₂ concentrations were connected to changes in the local wind patterns (east to west) that occur around noon in Calama. These changes determined that the emissions from the copper extraction and smelting operations (located north of Calama) could have been transported into the urban area, therefore causing the deterioration of its air quality that is perceived by the local population. No significant trends for SO₂ and O₃ concentrations were observed during 2013–2016, while an increase of 8.8% year⁻¹ for CO, and a reduction of 5% year⁻¹ for the other pollutants studied was observed.