In today's lecture, we'll discuss the impact of urban green spaces on mental health. Recent studies show that even small parks in city centers can significantly reduce stress levels among residents. Dr. Emily Carter from the University of London conducted a two-year experiment involving 500 participants. She found that people who visited a green area at least three times a week reported a 20% decrease in cortisol, a stress hormone. Interestingly, the size of the green space mattered less than the frequency of visits. However, she noted that noise pollution from nearby traffic could undermine these benefits, so planners should consider buffer zones of trees or shrubs.