Scientists have identified which tree species are most effective at filtering air pollutants, a finding reported by researchers affiliated with the University of Gothenburg. The study behind these insights involved a careful, controlled comparison of how different trees perform under the same environmental conditions, offering a rare view into the real-world capabilities of diverse species to capture airborne contaminants.
To conduct the analysis, researchers gathered leaves and needles from eleven varieties of trees growing within a single location in a botanical garden’s arboretum. This approach ensured that the trees shared similar exposure to air pollutants and grew under comparable weather and soil conditions. By examining what substances each species trapped, the team created a comprehensive picture of which trees contribute most to cleaner urban air where people live and work.
One of the study’s authors, Jenny Klingberg, emphasized the value of this design. She noted that testing many species under identical environmental pressures yields nuanced results that can inform city planners and environmental professionals. Overall, the research measured 32 distinct pollutants, including some that arrive in tiny micro and nano particle forms, which are challenging to monitor yet highly relevant to public health and air quality strategies.
The results showed meaningful differences in how tree species handle air pollutants. Coniferous trees tended to absorb higher amounts of gaseous polycyclic aromatic hydrocarbons (PAHs) than deciduous trees. This suggests conifers may play a particularly important role in removing certain vapors from the air, especially in seasons when outdoor pollution tends to rise. At the same time, hardwood species demonstrated a superior ability to scrub particulate matter from the atmosphere, thanks to their larger surface areas that provide more contact with polluted air as it moves past the leaves. Importantly, the study found that neither type of pollution significantly affected chlorophyll content or the photosynthetic capacity of the leaves studied, indicating that pollutant exposure did not compromise the trees’ basic biological function in the conditions observed.
Based on these findings, the authors advocate for a diverse mix of tree species in urban planning and landscape design. By combining conifers with hardwoods, city developers can maximize the overall air-cleaning impact across different pollutants and seasonal cycles, contributing to healthier urban environments for residents in North America as well as elsewhere. The takeaway is clear: a thoughtfully planned blend of trees can yield continuous air purification benefits throughout the year, complementing other air-quality measures rather than replacing them.