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Air Pollution Can be Mitigated Using Green Infrastructure!

By Dr. Anna Zakrisson

Realignment Project in Culver City, CA.  Photo courtesy of greenscreen

Air pollution causes a staggering 4-9 million deaths globally per year. 90% of the world’s population breathes air that exceeds the WHO air quality guidelines. Pollution source reductions are sorely needed, but effective pollution capture is equally impactful. Urban green infrastructure, such as the greenscreen trellis systems, can act as a pollution barrier and an air pollution capture system, thus improving the quality of life, and health, in urban areas.

The young and the old are the most affected

Air pollutants can be both natural and anthropogenic (man-made). In urban environments, anthropogenic air pollutants dominate and can primarily be attributed to the burning of fossil fuels from industrial processes, energy generation, and most importantly transportation.

As is often the case, the young and the elderly are the most vulnerable to air pollution. This is partly due to their limited range of movement and high air pollution exposure risks – especially as pollutants are suspended and resuspended in their local environment.

Air pollution, health scares, and costs

The Mark in Vancouver, BC.  Photo courtesy of greenscreen

Exposure to fine particulate matter, e.g., PM2.5, has been shown to increase the risk of acute respiratory conditions, lung cancer, heart disease, stroke, and COPD. An increase in the prevalence of Alzheimer’s and other neurological conditions has also been found. In addition, exposure to PM2.5 has been found to increase neonatal mortality.

Apart from immense suffering, The World Bank estimated a total financial loss of $143 billion in 2013 due to lost labor productivity after PM2.5 exposure. The global welfare losses due to PM2.5 were estimated to be $3.55 trillion. In 2016, the World Bank estimated that air pollution-related welfare losses were equivalent to 5% of the gross domestic product in high-income countries.

As such, green infrastructure is both an ethical and good economic decision.

Exacerbation through urban heat island (UHI) effects

Air pollution is often divided into primary and secondary pollutants. The primary pollutants are directly emitted from the source. The secondary pollutants, on the other hand, are formed from precursors originating from combustion (and other) processes. Further, the formation of these secondary pollutants is often exacerbated by high temperatures, which is bad news considering the increasing urban heat island (UHI) effects.

What we can do to indirectly affect air pollution is to cool our cities.  The introduction of green infrastructure would reestablish the natural water cycle, increasing the cooling effect via evapotranspiration.

How greenscreen can help protect your lungs

Residence in Oakland, CA.  Photo courtesy of greenscreen

Pedestrians are often exposed to high levels of air pollutants caused by vehicle emissions that become trapped at street level. Research studies have found that vegetated screens and walls that separate the traffic from pedestrians can significantly reduce harmful air pollutants.

greenscreen acts as both a direct capture of the pollutants and a dispersion agent , disrupting the airflow and diverting the poor-quality air away from the sidewalk. As an example: green facades were estimated to reduce PM10 by 50% and NO2 by 60% in a study by Abhijith et al. 2017. This can improve quality of life.

In summary: green infrastructure can achieve so much in our cities because it means working with nature rather than against it. GI can cool, reduce pollution, increase biodiversity, reduce energy costs, and re-establish the natural water cycle. Let’s green our streets, one by one!