An exploratory analysis of PM$$_{2.5}$$/PM$$_{10}$$ ratio during spring 2016–2018 in Metropolitan Lima

Aerosols (PM $$_{2.5}$$ 2.5 and PM $$_{10}$$ 10 ) represent one of the most critical pollutants due to their negative effects on human health. This research analyzed the relationship of PM and its PM $$_{2.5}$$ 2.5 /PM $$_{10}$$ 10 ratios with climatic variables in the austral spring (2016–2018) in Metropolitan Lima. Overall, there was an average PM $$_{2.5}$$ 2.5 /PM $$_{10}$$ 10 ratio of 0.33 with fluctuations from 0.30 to 0.35. However, there have also been high point values that reached ratios greater than one. This situation indicates a moderate condition of contamination by particulate matter with a predominance of coarse aerosols in spring, with an increasing trend over the years. The locations Ate and Villa Maria del Triunfo , especially Ate , presented poor quality conditions. Thursdays showed outstanding pollution peaks by PM $$_{10}$$ 10 , and a decrease is visible on Sundays. On the other hand, the PM $$_{2.5}$$ 2.5 showed a similar pattern every day, including Sundays. The maximum peaks occurred in the morning and night hours. The increase in anthropogenic emissions associated with the formation of secondary aerosols has been evident, being the case of the location Campo de Marte , the one that had a significant increase in ratios PM $$_{2.5}$$ 2.5 /PM $$_{10}$$ 10 , which confirms a greater intensity of secondary formations of carbonaceous particles from industrial oil sources, vehicle exhaust, as well as aerosols from metal smelting and biomass burning. There were negative correlations of the ratios with PM $$_{10}$$ 10 , temperature, wind speed, and direction, and positive correlations with PM $$_{2.5}$$ 2.5 and relative humidity. Contour lines were successfully developed that demonstrated the interaction of climate with PM $$_{2.5}$$ 2.5 /PM $$_{10}$$ 10 ratios. This will deepen the exploration of emission sources and modeling, which allows for optimizing air quality indices to control emissions and adequately manage air quality in Metropolitan Lima.