Long-term airborne particle pollution assessment in the city of Coyhaique, Patagonia, Chile

Highlights

• Air pollution assessment of PM_2.5 and PM₁₀ in a small town in Chilean Patagonia.

• Annual and daily air quality thresholds are greatly exceeded every year in this study.

• Pollution levels are associated with household firewood emissions during the coldest months.

• Coyhaique exhibits air pollution levels comparable to those of many polluted megacities.

Abstract

An air pollution assessment in a small city located in the heart of Chilean Patagonia is presented. Seven years (2014–2020) of PM concentration levels retrieved from two monitoring stations permits an evaluation of the city's pollution variability, the effect of meteorological variables and long-term trends of air pollution. The highest PM concentration levels observed during the coldest months are mainly related to an increasing emission associated with the intensive use of firewood for residential heating and cooking. The most polluted days are associated with low temperatures, low wind speed and high PM_2.5/PM₁₀ ratios, which is consistent with the predominance of local firewood sources over background emissions. A decrease in both PM fractions over time has been estimated (PM₁₀: -4.1, CI_99%: −5.7 to −2.9 and PM_2.5: -2.2, CI_99%: −3.5 to −1.3 μg m⁻³ year⁻¹). However, the annual average PM mass concentrations in Coyhaique exceeded both national and international air quality thresholds. The city reported a percent of annual exceedances of the daily WHO guidelines of 57% for PM₁₀ and 77% for PM_2.5. These numbers highlight the serious air pollution problem of the city of Coyhaique, which exhibits air pollution levels comparable to those of many polluted megacities in the world.