Managing Air Pollution: Strategies From Developed Cities

Air pollution is a pressing issue that affects cities worldwide, causing approximately 7 million premature deaths annually. It is a significant health threat, triggering asthma attacks, harming lung development in children, and even leading to fatal illnesses such as lung cancer. With 98% of cities in low- and middle-income countries failing to meet WHO air quality guidelines, the need for effective measures to combat air pollution is more critical than ever. Developed cities are taking innovative steps to address this challenge, implementing ultra-low emission zones, improving waste management practices, and promoting sustainable transportation options. As cities continue to grow and urbanise, finding solutions to reduce air pollution and protect public health becomes increasingly vital.

Emission standards for vehicles

In the United States, the Environmental Protection Agency (EPA) has been pivotal in establishing and enforcing vehicle emission standards. The Clean Air Act of 1963 (CAA) laid the groundwork by encouraging research and development for pollution reduction. The subsequent Motor Vehicle Air Pollution Control Act (MVAPCA) amendment in 1965 empowered the United States Public Health Service to set federal standards for vehicle emissions. By 1967, the federal government had the authority to enforce these emission standards, marking a significant step in addressing transportation-related air pollution.

California, facing severe air pollution and smog issues in the 1960s, took the lead in setting stringent vehicle emission standards. The establishment of the California Air Resources Board (CARB) in 1967, chaired by chemist Arie Jan Haagen-Smit, was instrumental in combating air pollution in the state. California's standards became a de facto benchmark for vehicle manufacturers nationwide. While other states considered less restrictive standards, fearing the loss of automobile manufacturers, the National Emissions Standards Act of 1967 prevented them from setting more stringent standards than the federal levels.

Over time, the EPA has continued to refine and update its emission standards. The latest standards finalized by the EPA cover a range of vehicles, including passenger cars, light-duty trucks, medium-duty vehicles, and heavy-duty vehicles for model years 2027 through 2032 and beyond.

Cities like London have successfully improved air quality through initiatives such as the Ultra Low Emission Zone (ULEZ), which has led to a significant reduction in NO2 levels and hospital admissions for asthma attributable to air pollution. Similar low-emission zones are being expanded in cities like Madrid, Milan, and Seoul, incentivizing cleaner modes of transportation.

Urban gardens and greenery

One of the key benefits of urban gardens and greenery is their ability to capture and filter rainwater, preventing water bodies from being contaminated with pollutants. Rain gardens, combined with Sustainable Drainage Systems (SuDS), effectively manage rainwater runoff, trapping pollutants before they can enter water bodies and potentially evaporate back into the air. Green screens, often utilizing English ivy due to its rough leaf texture and high leaf density, act as a blockade to trap and disperse pollution, especially in areas bordering busy roads.

Urban trees and vegetation play a significant role in reducing traffic hazards and improving driving safety. The presence of trees and roadside vegetation can calm traffic and reduce stress levels in drivers. Additionally, trees help purify water, improve air quality, mitigate flooding and droughts, aid in soil fertility and erosion control, and bind toxic substances. Urban forests provide a source of sustenance, offering edible plants, exotic fruits, and nut-bearing trees for community members.

Community gardens foster social connections and improve nutrition by providing access to fresh produce. They also contribute to a reduced carbon footprint and lower environmental risks associated with the food supply chain. Individual gardeners often employ ecological agricultural practices, minimizing the use of chemical fertilizers and pesticides, further reducing pollution and potential health risks.

While urban greenery is a powerful tool in the fight against air pollution, it should be noted that sustained pollutant deposition on foliar surfaces can negatively impact tree physiology, reducing their pollutant removal capacity. Therefore, it is essential to be mindful of the potential drawbacks and ensure the proper maintenance of urban green spaces to maximize their benefits in improving air quality.

Waste management

One of the key strategies in waste management is minimizing waste generation in the first place. This involves encouraging companies to use less packaging and create products that produce less waste. Additionally, products should be designed for easy recyclability, and companies should support regulations for improved waste management.

When waste cannot be avoided, the next best option is to recover materials and energy through recycling, remanufacturing, and waste-to-energy processes. Recycling, in particular, offers substantial resource savings and contributes to job creation. Composting is another effective waste management technique that can curb air pollution and promote economic growth.

In addition to these initiatives, governments play a crucial role in establishing strong regulations to prevent dumping and burning. By investing in better waste handling methods and technologies, governments can significantly improve air quality and create a safer environment for their citizens.

Some cities have already made notable progress in waste management, reducing air pollution, and improving public health. For example, Dakar, the capital of Senegal, has rehabilitated former waste burning sites, creating job opportunities and reducing air pollution from open burning. Similarly, Addis Ababa, the capital of Ethiopia, has expanded waste management initiatives with composting and recycling programs, emphasizing their role in curbing air pollution and promoting inclusive economic growth. These success stories highlight the importance of waste management in the broader effort to combat air pollution in developed cities.

Low-emission zones

Priced LEZs restrict vehicles by charging drivers a fee to enter, with higher-polluting vehicles paying a higher fee, while hybrid or electric vehicles pay a lower fee or enter free of charge. Non-priced LEZs, on the other hand, ban the highest-polluting vehicles from entering the zone, with violators typically facing significant fines. The size, stringency, enforcement, and the presence of non-car alternatives can influence an LEZ's impact on air quality.

LEZs are primarily implemented as a strategy to improve air quality and reduce transport-related pollutants, such as particulate matter and nitrogen oxides, which are detrimental to both air quality and human health. They have grown in popularity as a strategy for cities to reduce their dependence on motor vehicles and promote cleaner, more affordable, and accessible alternatives. For example, London's Ultra Low Emission Zone (ULEZ) initiative delivered a 36% reduction in NO2 in the first six months after its launch in 2019. Additionally, over 95% of vehicles in London are now compliant with ULEZ emissions standards, and the city has seen a 30% reduction in hospital admissions for asthma attributable to air pollution between 2017 and 2019.

Other cities with LEZs include Paris, where certain vehicles are prohibited from entering during its operational hours of 8 am to 8 pm on weekdays; Berlin, Cologne, Hanover, Mannheim, and Stuttgart in Germany; and Milan, Palermo, and Rome in Italy. Outside of Europe, LEZs are being piloted in major cities such as Rio de Janeiro, Brazil; Haifa, Israel; Seoul, South Korea; and several Chinese cities, including Beijing.

Banning cars

A study published in June 2023 found that older diesel cars emitted up to 10 times the permitted level of nitrogen oxide (NOx) when driven in urban areas. This has prompted calls for regulators to enforce higher emissions standards. Cities that have banned polluting vehicles have seen improvements in the health of their citizens, according to a study published in The Lancet. London's Ultra Low Emission Zone (ULEZ) initiative, for example, delivered a 36% reduction in NO2 in the first six months after its launch in 2019, and a 30% reduction in hospital admissions for asthma attributable to air pollution between 2017 and 2019. The ULEZ scheme was supported by a £270 million scrappage programme that enabled Londoners, businesses, and charities to replace or retrofit their older, polluting vehicles with cleaner alternatives.

Beijing, China, provides another successful example of banning cars to reduce air pollution. The city implemented a one-day-a-week ban that reduced particulate matter by about nine percent in five years. Additionally, new fuel quality and emission standards for vehicles, along with controls on power plant and industrial emissions, contributed to a 36% reduction in PM2.5 levels.

However, banning cars has not been effective in all cities. In Mexico City, for instance, banning cars on Saturdays did not reduce air pollutants, as residents found creative ways to circumvent the restrictions, such as carpooling, using taxis, and purchasing extra vehicles. Paris also attempted to ban tens of thousands of cars based on their license plate numbers, but the policy was abruptly called off after facing significant disruption and pushback.

While banning polluting cars can be challenging and may not always yield the desired results, it is essential to explore various strategies to tackle the global menace of air pollution, which causes approximately 7 million premature deaths each year. Cities can learn from the successes and failures of other cities to develop effective policies that improve air quality and protect the health of their citizens.

Frequently asked questions