Trees absorb carbon dioxide and other atmospheric pollutants

At school we are taught that trees and other plants absorb carbon dioxide, produce sugars and cell growth and expel oxygen into the atmosphere. There are many values assigned to this gas exchange in terms of atmospheric carbon dioxide reduction but an oft quoted figure is 730kg CO2/100yrs of life. That means that we need to plant more than 4 broadleaved trees per year per average family car and leave those trees standing to maturity.

Carbon dioxide is often seen as a global issue and so planting those trees in the countryside to create new forests is a great way to ‘offset’ our CO2 emissions. However the particulate emissions in diesel exhaust must be viewed from a local perspective. Studies show that a range of PM10 and smaller related diseases and conditions are far more frequent and severe near busy roads.

Trees are very effective in reducing airborne particulate matter. Experimentally we have evidence that a hedge of privet (Ligustrum aurea) 50cm thick can reduce some pollutant levels from the ‘extremely toxic’ levels to ‘harmless’ when fed to Stick insects (Carausius morosus). There are various mechanisms in action in the deposition of particulate matter. Some material is small enough to enter the leaf either via the leaf pores or through chemical absorption. The majority of the material settles on the leaf surfaces and falls to the ground either as ‘dust’ or is washed off by rain water.

These atmospheric effects are additional to the noise damping effects of foliage. They are also in addition to the cooling effects of the trees in their micro-climates by a) shading the surrounding ground and b) cooling of the air by the release of moisture via transpiration. This and the above effect can make trees very valuable on the road or street side.

ChemEcol is committed to plant one tree for every 12 bottles of fuel treatment sold.