A study reveals that not all trees improve urban air quality.

[{"selector":"#anim-64fda28d-f134-48af-90d2-8c0bc7f7e1b6 [data-leaf-element=\"true\"]","keyframes":{"transform":["translate3d(31.249999886225726%, 0, 0)","translate3d(0%, 0, 0)"]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"both"}] According to a study by the Federal Technology Institute Lausanne (EPFL), not all trees are equally capable of enhancing the quality of the air in cities. According to a study by the Federal Technology Institute Lausanne (EPFL), not all trees are equally capable of enhancing the quality of the air in cities.