Assessment of NO₂ and SO₂ emissions in the Tula industrial complex, Hidalgo, using the mobile mini-DOAS technique...

The Tula industrial complex, located in Hidalgo, is a major contributor to air pollution in Mexico, particularly NO₂ and SO₂. This study used the mobile mini-DOAS technique to quantify the emissions of these gases over a period of seven measurement campaigns conducted from 2022 to 2024. The measurement campaigns carried out in summer and winter recorded the highest emission fluxes, which correlated with a higher electricity demand. The variations observed were associated with fluctuations in industrial activity and meteorological conditions. The results for 2022 and 2023 showed a decrease in emissions compared to previous studies, which could be attributed to the recent introduction of natural gas for electricity generation. However, a significant increase was observed in 2024, which was correlated with an increase in activity at the Miguel Hidalgo Refinery. The emissions quantified with DOAS were used to implement the AERMOD model, which allowed the dispersion of NO₂ and SO₂ to be assessed. This model was implemented in a 15 km radius around the Tula industrial complex, considering meteorological and topographical variations in the region. The dispersion of pollutants was mainly directed to the west and south of the industrial complex. The results indicate that the concentrations of NO₂ and SO₂ exceeded the permissible limits established by official Mexican standards in several of the measurement campaigns. While all of the identified communities were affected by the emissions, Bomintzha, La Amistad, and San Miguel Vindho were the most affected due to their proximity to the complex, altitude, and prevailing wind direction.