Can Trees increase ground-level Ozone?
To make a city greener one way is to plant more trees. However, scientists have found something that is counter-intuitive. Urban Vegetation can increase pollution, especially during a heatwave. This can also include the formation of ozone. The reference is @ ACS journal - environmental science & technology.
We have read many times how trees can have many benefits. These benefits can include carbon reduction, water retention and shade is another benefit. What you might not know is that trees release volatile organic compounds (VOC's). These voc's can engage with other substances and contribute to air pollution. When it is hot trees release more voc's! Churkina wanted to see how heat waves affect air pollution during heat waves.
Air pollution concentrations were compared in Berlin in the summer of 2006. This summer had a heatwave! Then data was collected from the same location in 2014 under normal conditions. The results were that local vegetation contributed between 6 to 20% of the ozone formation. Then the data from 2006 showed that the contribution spiked at 60% !
The researchers suggest that cities look to other methods of reducing vehicular traffic which is major source of nitrogen oxides that react with voc's that form ozone. The alternative is to keep trees trimmed and serviced. Tree Felling experts can often advise on this.