Air quality assessment through AERMOD model: a case study of an asphalt plant in Brazil

Asphalt plants’ emissions still need to be investigated regarding the impacts on air quality. This research analyzes particulate matter (PM) and combustion gases emitted during hot-mix asphalt production in a drum-mix asphalt plant located in a metropolitan region in Brazil. Emissions from the stacks (dryer drum and asphalt heater) and the traffic of trucks on unpaved roads within the company’s limits were assessed. The AERMOD software   was used to assess the emissions' amplitude, frequency, and dispersion. Six scenarios were evaluated: scenarios one, two, and three, corresponding to the emissions of nitrogen dioxide (NO₂), sulfur dioxide (SO₂), and total suspended particulates (TSP), respectively, due to the combustion of shale oil in the dryer drum and diesel oil (asphalt heater). The concentrations of PM_2.5, PM_10, and TSP, due to the traffic of trucks and the dryer drum, correspond to scenarios four, five, and six, respectively. The findings indicate compliance with Brazilian standards for NO₂ (Scenario 1) and TSP (Scenario 3), but violations for SO₂ (Scenario 2) due to shale oil use. Seasonal variations affect dispersion, with TSP and SO₂ (Scenario 1 and 3) peaking in winter and spring, and NO₂ (Scenario 2) in spring and summer, especially at night. PM_2.5 emissions (Scenario 4) follow the standards, but PM₁₀ (Scenario 5) and TSP (Scenario 6) exceed limits, notably in fall, winter, and spring. Unpaved roads are  significant PM sources in asphalt plants and AERMOD findings suggest  this. Understanding pollutants’ sources and seasonality is crucial for air quality protection.