Determinação de NO2, O3 e MP10 em Curitiba e região metropolitana

Abstract

Air pollution is responsible for around 7 million deaths per year, according to the World Health Organization (WHO), mainly in cities with a large flow of vehicles, industries and other activities that can contribute to an increase in gas and particle emissions. Or its precursors. The objective of this work is to determine the concentrations of NO2, O3 and PM10 in the atmosphere of Curitiba and the Metropolitan Region (Almirante Tamandaré and São José dos Pinhais) and to propose a method using digital images to quantify the gases evaluated. Collections were carried out monthly (from August 2021 to August 2022) at four different points, taking place indoors (two kitchens and two laboratories) and outdoors. Sampling for O3 and NO2 gases lasted 7 days, using Ogawa-type passive samplers, and 24 hours for MP10, using a large volume sampler. For the quantification of gases, a UV-Vis spectrophotometer was used and digital images produced directly from the filter (only for O3) and in solution for both gases, using the R and G channels as analytical signal for samples containing O3 and NO2, respectively. The concentration of MP10 was determined by the difference between the masses before and after collection. Points 3 and 4 (external) had NO2 averages of 8.20 and 10.17 μg m-3, respectively, higher than those recorded in points 1 and 2 (5.02 and 4.32 μg m-3), as they are located in places with greater vehicle flow, resulting in greater NOX emissions. In the internal environment, point 1 had the lowest average concentration of NO2 (4.56 μg m-3), as it is a laboratory used only to store glassware and reagents. At points 2 and 3 (domestic kitchens) the averages were 6.41 and 12.26 μg m-3, as they have internal emission sources. Point 4 (research laboratory used daily) presented an average concentration of 6.71 μg m-3, which can be justified by the entry of external air, as the site’s windows are commonly open during the day. In most of the months evaluated, points 1 and 2 presented higher concentrations of O3 to the external environment (32.15 and 27.12 μg m-3, respectively), which coincides with lower levels of NO2, demonstrating the relationship between them. In the internal environment, locations 1 and 2 presented the highest average O3, with 10.44 and 15.08 μg m-3, and points 3 and 4 with 4.95 and 1.70 μg m-3, respectively, highlighting the influence of the air transported into the internal environment. In relation to PM10, the external environment (Point 4) presented a concentration variation of 24.51 to 93.6 μg m-3. For months with higher rainfall, the values were lower, as this condition favors the removal of pollutants from the atmosphere. Internally, concentrations ranged from 6.52 to 27.95 μg m-3. In order to verify the effectiveness of digital image analyses, a paired t-test was performed and the results were in agreement for all points, at a confidence level of 95%, which demonstrates its potential as a low-cost and easy-to-apply tool. For the quantification of the atmospheric gases investigated.