Trees can also have negative effects by increasing pedestrian exposure to pollution if they are introduced in heavily travelled street canyons where air pollutants can be trapped . To maximise the adaptation benefits of NBS for improving air quality, planners and managers can target tree selection for species with low VOC emissions, low allergen emissions and high pollutant deposition potential , and combine with low pollution transportation policies. Studies suggest sensitive planting of roadside tree canopies can have positive effects on air pollutants . For example, Xue et al.  found that the PM2.5 reduction between 2013 and 2017 in China was associated with a saving of approximately USD 111 billion yr1 nationally. Tree planting near schools, nursing homes and hospitals can ensure that benefits provided by trees are delivered to the local populations that stand to benefit the most from improved air quality, but species need to be adapted to regional climate to provide benefits over time .
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report