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Researcher at Universidad de Santiago studies the impact of trees on reducing environmental pollution

  • Dr Sergio Castro, researcher at the Center for the Development of Nanoscience and Nanotechnology and professor at Faculty of Chemistry and Biology of Universidad de Santiago de Chile, has been studying for years the effect of three tree species in Santiago that capture atmospheric ultrafine particles and nanoparticles which are harmful to health. For this reason, they are an important factor to improve air quality.

 

 

For years, Dr Sergio Castro, researcher at the Center for the Development of Nanoscience and Nanotechnology (Cedenna) of Universidad de Santiago de Chile has been studying the impact of trees on the urban atmosphere. The researcher has evaluated the behavior of three widely spread species that are used as ornamental trees in Santiago (Nerium oleander, Pittosporum tobira, and Ligustrum lucidum) and which characteristics could contribute to reduce the amount of atmospheric particles during the whole year.

Contrary to most of the trees in the city, these three species keep their leaves during the winter, allowing to capture small particles in the air from oil pollution and others in the most critical season of the year.

Currently, the World Health Organization suggests guidelines to assess the quality of air based on the concentrations of PM10 and PM2.5, that is to say, particulate matter between 10 and 2.5 microns in diameter, respectively.

However, there are even smaller particles that are not included in the Chilean standard, although they have been recognized in some environmental studies. These particles of ultrafine matter or nanoparticles are known as PM 0.1 (01, micron in diameter). They are ultrafine fractions of airborne dust that are also derived from the combustion of hydrocarbons.

“This matter has a stronger impact on human health than bigger particles, as it is directly absorbed by alveoli, and long-term exposure can cause chronic respiratory illness and even cancer,” Dr Castro explains.

Different studies have shown that trees can retain atmospheric particulate matter in their leaves, contributing to mitigate air pollution. However, most of the trees in Santiago lose their leaves during winter, as they are deciduous. Dr Castro’s study suggests that increasing vegetation in Santiago and selecting species that are more efficient at retaining atmospheric particles would improve the mitigating effect between 10% and 20%. This result could contribute to public policy making regarding urban air quality. Part of the study has already been published in the journal Water, Air and Soil Pollution.

Planning the city 

In the second half of the 19th century, Santiago city was remodeled imitating European architectural and ornamental trends. The process included embellishing the first parks with exotic species and native trees were not considered.

Having more exotic species than native ones poses an additional problem that has not been explored up to now. Projected climate changes for Chile suggest that water availability will be of critical importance to the country. As the exotic trees in our country come from different climatic zones, they require more water. Therefore, these ornamental species will have an impact on the city’s water economy.

According to Dr Castro, it is necessary to start planning a thoughtful and sustainable system to replace those ornamental species. “Ideally, we should use native plants and trees as ornamental species in Santiago, favoring their preservation and contributing to a better water economy,” he concluded.

Translated by Marcela Contreras

Autor: 
Sandra Gómez