Researchers at Jinan University have found that some trees can significantly worsen urban air quality. In hot weather, poplars and weeping willows emit more harmful substances than cars, reports infohub.kz.
At temperatures of +35°C, these trees, along with oaks, release high concentrations of isoprene. When interacting with nitrogen oxides, this substance forms ground-level ozone, which irritates mucous membranes and causes coughing. Trees account for more than half of harmful ground-level ozone, as reported by the South China Morning Post.
According to the study, when the temperature in Beijing rises from +20°C to +35°C, the rate of isoprene breakdown from trees in the atmosphere increases about sevenfold. Meanwhile, pollution from human activities increases by about 40% in hot weather.
However, scientists are not calling for the felling of willows and poplars, as they still provide shade and absorb carbon dioxide. Instead, they suggest gradually increasing the share of other tree species in the city. Replacing just 10% of willows and poplars would reduce isoprene emissions by 29%.
Krasnoyarsk scientists commented on the study and called for a comprehensive approach: not only increasing the planting of other tree species but also reducing nitrogen oxide emissions. If isoprene from trees does not react with nitrogen oxides, it is not dangerous. To achieve this, for example, a switch from coal to gas is needed.
It is worth noting that pyramidal poplars were once considered a hallmark of Almaty, but they are now being gradually replaced by other tree species. Earlier, Kursiv LifeStyle reported that due to smog in Almaty, schoolchildren lose approximately 7–8 IQ points.