Plants
Plants are very diverse in spite of a common ancestor Pixabay

Adding plants and trees near factories and other pollution sources can reduce air pollution, but potted plants are barely helpful in improving the air quality, scientists have said. According to researchers, plants – not technologies – are a cheaper option for cleaning the air near industrial sites, roadways, and power plants as trees reduce air pollution by an average of 27 per cent.

Another study, however, suggests that it will take up to 93 plants per square foot of floor space to compete with an office ventilation system and opening a couple of windows can achieve the same effect. The study concluded that pot plants brightened up homes and office spaces but their atmosphere-cleansing abilities were "vastly overstated" as they did not help reduce pollution by purifying the air.

Bhavik Bakshi, lead author professor of chemical and biomolecular engineering at Ohio State University, said people needed to start looking at nature and respecting it as nature-based solutions to air pollution were better than technology. The study published in the journal Environmental Science and Technology found that technology was cheaper at cleaning the air than ecosystem upgrades in one specific sector -- industrial boilers.

The researchers collected public data on air pollution and vegetation on a county-by-county basis across 48 states in the US. They then calculated to find that after restoring vegetation to county-level average canopy cover reduced air pollution by an average 27 per cent across all counties.

Bakshi said the research did not calculate the direct effects plants might have on ozone pollution because of lack of data on ozone emissions, and also did not consider whether certain species of trees or plants better "scrubbed" pollution from the air, though it was likely that the species of plant made a difference in air quality.

According to the American Lung Association, about four in 10 people in the US inhale poor air, leading to health issues including asthma, lung cancer, and heart disease. Bakshi said their findings indicated that engineers and builders needed to incorporate both technological and ecological systems.

Another study author and environmental engineer Michael Waring of the Drexel University in Philadelphia stressed plants soaked up dangerous chemicals too slowly to significantly improve air quality. "Plants are great, but they don't actually clean indoor air quickly enough to have an effect on the air quality of your home or office environment," said the author of the study published in the Journal of Exposure Science and Environmental Epidemiology.

He added that ventilation systems or even opening a window reduced volatile organic compounds (VOCs) much quicker than plants. According to the Royal College of Physicians, indoor air pollution contributes to 99,000 deaths across Europe every year. Waring said the rate at which plants dissipated VOCs in a chamber was orders of magnitude slower than the standard rate of air exchange in a building.

Nature-based solutions were, however, a major theme during the United Nations Climate Action Summit in September this year to prod countries for doing more and fight climate change, where governments pledged more money to preserve forests, restore wetlands, and deploy sustainable agriculture practices in developing countries. An Intergovernmental Panel on Climate Change report earlier this year stated that destructive patterns of land use accounted for 23 per cent of human-caused greenhouse gas emissions.