Urban air pollution is a huge public health issue — it kills more than 3 million people every year, according to the latest World Health Organization estimates.
According to the latest urban air quality database, 98% of cities in low- and middle income countries with more than 100 000 inhabitants do not meet WHO air quality guidelines. However, in high-income countries, that percentage decreases to 56%. In the past two years, the database – now covering 3000 cities in 103 countries – has nearly doubled, with more cities measuring air pollution levels and recognizing the associated health impacts.
As urban air quality declines, the risk of stroke, heart disease, lung cancer, and chronic and acute respiratory diseases, including asthma, increases for the people who live in them. "Air pollution is a major cause of disease and death. It is good news that more cities are stepping up to monitor air quality, so when they take actions to improve it they have a benchmark," says Dr Flavia Bustreo, WHO Assistant-Director General, Family, Women and Children's Health. "When dirty air blankets our cities the most vulnerable urban populations—the youngest, oldest and poorest—are the most impacted."
More than half of the monitored cities in high-income countries and more than one-third in low- and middle-income countries reduced their air pollution levels by more than 5% in five years. Reducing industrial smokestack emissions, increasing use of renewable power sources, like solar and wind, and prioritizing rapid transit, walking and cycling networks in cities are among the suite of available and affordable strategies.
"It is crucial for city and national governments to make urban air quality a health and development priority," says WHO's Dr Carlos Dora. "When air quality improves, health costs from air pollution-related diseases shrink, worker productivity expands and life expectancy grows. Reducing air pollution also brings an added climate bonus, which can become a part of countries' commitments to the climate treaty."
While major transportation and infrastructure changes take time, researchers at the Wageningen University in The Netherlands are testing a more immediate solution: a new type of honeysuckle called Green Junkie. This new honeysuckle is bred to consume more carbon dioxide — in other words, it eats smog.
"The parts of a plant that pick up air pollution out of the air are the 'hairs,' so what they've changed for this honeysuckle is that they've made it very, very hairy," Emily Parry from AMS Institute, told FastCoExist. The leaves of the plant are bigger and hairier than typical honeysuckle, and they grow more quickly, too. And it's fed with a special organic fertilizer made with plant waste collected from the city.
According to The Green City, right now, it's not clear how significant the impact of this new honeysuckle could be, and researchers will know more this fall when testing has concluded. It makes sense that plants would be hybridized for pollution cleanup of a specific kind. Many plants absorb pollution — so much so that NASA has long promoted a list of those that can keep indoor air cleaner — and many homeowners choose plants that are particularly good at doing so. Some grasses and ivy are already used in traffic medians and roadsides specifically because they can reduce particulate pollution by up to 60 percent.
Many of us imagine cities of the future as more verdant spaces than they are today. If some plants can keep air cleaner for urban residents while adding green to the landscape, they'll provide double the benefit for us.