Dense Tree Plantings Along Roads Increase Levels Of Harmful Pollutants

More trees mean cleaner air, right? Not necessarily, suggests a new study looking at the wooded areas next to roadways. Instead, lines of trees known as “greenbelts” might actually trap a common pollutant from vehicle exhaust—nitrogen dioxide (NO2)—boosting on-the-ground levels of the gas up to 21%. That could make breathing hard for bikers and pedestrians with asthma or other respiratory diseases. (Click on title for full story.)