A recent international study revealed trees to have significant air pollution mitigation potential in urban areas with substantial amount of particulate matter (PM10). The study entitled, “Estimating the removal of atmospheric particulate pollution by the urban tree canopy of London, under current and future environments” was published in the recently released November issue of the journal Landscape and Urban Planning. The study focuses on the potential of coniferous and broadleaf trees to sequester atmospheric particulate matter, in addition to their natural ability to remove carbon dioxide (CO2). The study was carried out in London; however the results are shown to have applicability on a global scale.
The researchers conducted several experiments to calculate how much atmospheric particulate matter was present in areas with limited tree coverage. Additional experiments were conducted in areas with significant tree canopy coverage and measured for levels of particulate matter. The results demonstrate that trees are able to remove between 850 and 2100 tonnes of PM10 annually. The modeling approaches used by the researchers consider several different tree species, allowing a greater understanding of which type of tree has optimal sequestration capabilities. The study concluded that coniferous tree species posses the ability to remove higher concentrations of PM10.
The use of seasonal rather than hourly data had little to no impact on modeled annual data for captured PM10, suggesting that pollution uptake can be estimated in other cities and for the future where hourly data are not available. This is an important finding because predictions will remain accurate, despite changes in climate and levels of emissions. There are also urban planning benefits that result from this study, as planners can redesign city blocks with the appropriate tree species that will provide the highest air quality. Tree planting programs in London can be mimicked in areas where the climate is conducive to coniferous and broadleaf trees species growth.
As particulate matter is harmful to human health, the need for purer air quality is increasing rapidly. According to the EPA, exposure to particulate matter can result in severe respiratory symptoms, decreased lung function, exacerbation of existing asthma, nonfatal heart attacks, and even premature deaths in children with severe lung diseases. As the debate over increased regulatory action and its effects on industry and the economy continue to gain momentum, alternative solutions such as the findings presented in this study could be seen as a common sense approach to air quality issues. Trees could be the answer to some of the most troubling air pollution issues.