Cities' Strategies To Reduce Air Pollution: Funding Clean Air

Air pollution is a pressing issue faced by cities worldwide, with urban residents breathing unhealthy levels of pollution. Cities are taking various approaches to combat this problem and improve air quality. One innovative approach is the implementation of urban gardens and green spaces, which absorb pollutants and release oxygen, improving air quality and reducing greenhouse gas emissions. Additionally, cities are investing in renewable energy sources, such as solar plants and wind farms, to reduce greenhouse gas emissions and air pollutants. To reduce vehicle emissions, cities are encouraging the use of sustainable transportation options, such as public transportation, electric vehicles, and cycling infrastructure. Cities are also implementing low-emission zones and intelligent traffic management systems to reduce traffic congestion and idling vehicles, which contribute to air pollution. These interventions are supported by air quality monitoring networks that provide real-time data on pollution levels, helping cities evaluate the effectiveness of their initiatives.

Low-Emission Zones

The effectiveness of LEZs varies depending on factors such as the emissions standard set, the geographical area of the LEZ, and the types of vehicles affected. Some LEZs apply only to lorries and buses, while others include taxis, cars, and motorcycles.

A review of research published in the Lancet Public Health journal found that five out of eight LEZ studies showed a clear reduction in heart and circulatory problems when an LEZ was implemented. These studies were conducted in Germany, Japan, and the UK, and found fewer hospital admissions, fewer deaths from heart attacks and strokes, and fewer people with blood pressure problems.

The London Ultra Low Emission Zone (ULEZ) has contributed to a nearly 50% reduction in toxic Nitrogen Dioxide pollution in central London. Similarly, the impact of the Milan Ecopass and Area C schemes has been a reduction of traffic emissions by 18% for PM10, 10% for NOx, and 22% for CO2.

While LEZs have been shown to improve air quality and health outcomes, there is also evidence that they can cause transitory yet long-lasting reductions in individuals' life satisfaction. This suggests that the subjective well-being effects of restricting mobility may outweigh the benefits of improved health.

Active mobility and green spaces

The Clean Air Fund's C40 Clean Air Accelerator is a global coalition of 49 cities across six continents that have committed to tackling greenhouse gas emissions, air pollutants, and inequities. One of their initiatives involves enabling active mobility and greening spaces.

Many cities are working to promote active mobility to create a healthier, greener, fairer, and safer public space that promotes social relations and the local economy. For example, Barcelona's Superblock programme is transforming the entire city's street model by pedestrianising one out of three streets. Buenos Aires has expanded its cycle infrastructure to a total of 267 km of cycle lanes, while Paris is implementing a new bicycle plan to become a 100% bikeable city by 2026.

In addition to promoting active mobility, cities are also expanding their green spaces. Trees and plants can help to reduce air pollution and lower temperatures in urban areas. They can also provide shade, reduce the demand for air conditioning, and promote biodiversity. For instance, Sydney's Greening Strategy and the city of Guadalajara, which planted 22,000 endemic trees in 2022, are excellent examples of urban greening initiatives.

By investing in active mobility and green spaces, cities can improve air quality, promote social equity, and create more sustainable and resilient communities. These initiatives not only benefit the environment but also have positive impacts on the health and well-being of residents.

Green Spaces and Health

Urban green spaces, such as parks, gardens, and playgrounds, offer numerous health benefits to residents. They provide opportunities for physical activity, social interaction, and stress reduction. Studies have shown that access to green spaces is associated with improved mental health, reduced depression, improved pregnancy outcomes, and lower rates of cardiovascular disease, obesity, and diabetes.

In addition, urban green spaces can help to reduce health inequalities. Disadvantaged communities often have limited access to green spaces, but they stand to benefit the most from them. Increasing the availability and quality of green spaces in these areas can promote health equity and reduce disparities related to income, minority status, and other socioeconomic factors.

Vegetation and Air Pollution

Vegetation and green spaces have been shown to reduce concentrations of air-borne pollutants, particularly particulate matter (PM). Green spaces can affect air quality through particle deposition, dispersion, and modification. The most studied mechanism is deposition, which involves the measurement of mass and settling velocity of PM on plant leaves.

The effectiveness of green spaces in reducing air pollution varies depending on the scale and context of the intervention. Factors such as plant selection, spatial setup, ventilation, and maintenance play a crucial role in optimising the air pollution reduction capabilities of green spaces.

Recommendations for Cities

When rethinking public space design, cities should consider the diverse optimisation options for green space interventions. This includes selecting the right types of plants, designing spatial setups that promote ventilation and airflow, and maintaining green spaces properly. Additionally, cities should address supplementary vegetation effects, such as temperature regulation and water management.

By adopting an integrated and risk-based approach to PM mitigation through green space interventions, cities can effectively reduce air pollution, promote health, and create more sustainable and resilient communities.

Public transport

One way that cities are investing in public transport to reduce air pollution is by electrifying bus fleets. Electric buses produce fewer emissions, improving air quality, and are quieter, reducing noise pollution. Many cities are transitioning their bus fleets to electric, with some offering incentives for bus operators to make the switch. For example, London has committed to making its entire bus fleet zero-emission by 2037, with a £75 million fund to support the transition. Similarly, the

Air quality monitoring

Cities like Bogotá and Quezon City have expanded their air quality monitoring networks by deploying microsensors and additional sensors, respectively, to collect valuable information on top of their existing monitoring infrastructure. This allows them to gather more detailed data and improve the accuracy of their air quality measurements.

In the United States, Houston, Texas, has secured a $500,000 EPA grant to deploy nine air quality sensors and a mobile monitoring unit to track air quality conditions over the next three years. This data will guide the city's officials in implementing effective pollution mitigation strategies. Similarly, the Washington state Department of Ecology has started deploying 50 air-quality monitors to track the prevalence of air pollutants and support the establishment and enforcement of pollution regulations and standards.

Additionally, air quality monitoring can help cities identify areas with high levels of specific pollutants and take targeted action. For instance, cities with high vehicle traffic tend to have elevated NO2 levels, while cities in low- and middle-income countries often have higher PM2.5 pollution due to vehicle emissions, coal-burning power plants, and industrial emissions. By monitoring these pollutants, cities can implement measures to reduce emissions and improve air quality.

Overall, air quality monitoring is a vital tool for cities to address air pollution issues and ensure the health and well-being of their residents. By collecting and analyzing data, cities can make informed decisions, evaluate the effectiveness of their initiatives, and create healthier urban environments for their populations.

Green construction practices

The construction phase of a building's life cycle can have a significant impact on air quality. For instance, the use of polluting kilns for brick production contributes to global black carbon emissions. Green construction practices aim to reduce these emissions by advocating for the use of cleaner technologies and more efficient production methods. Additionally, the use of toxic building materials, such as asbestos, can have long-term health consequences for those exposed to indoor air pollution. Green construction practices prioritise the use of sustainable, non-toxic, and air-purifying building materials to limit off-gassing of pollutants within buildings.

Another important aspect of green construction is the focus on energy efficiency. Buildings are responsible for a significant portion of global energy-related carbon emissions, particularly during the operational phase. Green construction practices promote the use of renewable energy sources, such as solar power, and the implementation of energy-efficient appliances and heating systems. This not only reduces air pollution but also contributes to lowering energy costs and improving thermal comfort for occupants.

Furthermore, green construction practices emphasise the importance of ventilation and indoor air quality. Proper ventilation strategies can reduce the risk of mould and the accumulation of pollutants, such as volatile organic compounds (VOCs), inside buildings. The WGBC promotes the use of purification systems and advanced filtration technologies to ensure that indoor spaces have sufficient fresh air while filtering out harmful microbes and particulates.

Overall, green construction practices play a crucial role in reducing air pollution by promoting the use of sustainable materials, energy-efficient design, proper ventilation, and the development of green infrastructure. By integrating these practices into construction and urban planning, cities can create healthier and more environmentally friendly spaces for their residents.

Frequently asked questions