Is the existing urban greenery enough to cope with current concentrations of PM2.5, PM10 and CO2?

Abstract

Poor air quality in urban areas has a direct impact on the public health on a global scale. The examples of air pollution are: particulate matter with particles less than 10 μm (PM10) and less than 2.5 μm (PM2.5), as well as carbon dioxide (CO2). Urban greenery can be a way to clean the air in built-up areas. Many urban parks were, however, created long time ago, and it was not examined whether they are useful for the air purification nowadays. In year 2017, in the area of the largest city park in Europe – the Silesia Park (S Poland) – a network of 40 constant points was created, where from June to October the air quality was measured once a month. Research showed that the air quality was lower near the roads, the microclimate affected the concentration of pollutants, and trees of different genera and sizes differed in the efficiency of air cleaning. The greater porosity of tree crowns was associated with a higher concentration of all three measured indicators, suggesting their stagnation between vegetation. Older patches of the park with European hornbeams and beeches deserve protection as the most efficient air filterers. It is recommended to close internal park roads for cars and/or plant a new green barrier around the park. Current density of trees should be constant or increased to maintain the optimal microclimate that decreases air temperature determining effective air cleaning.