Today, in our environmental science lecture, we'll discuss the impact of urban green spaces on air quality. Recent studies show that parks and gardens can reduce local temperatures by up to 3 degrees Celsius. However, the key factor is not just the size of the green area but the diversity of plant species. Trees with broad leaves, for example, are more effective at trapping particulate matter than conifers. Additionally, green roofs on buildings can lower energy consumption by 15%, but they require regular maintenance. So, when planning sustainable cities, we must prioritize both quantity and variety of vegetation.