NATURE-BASED SOLUTIONS TOWARDS AIR QUALITY:CHALLENGES AND OPPORTUNITIES

Urbanization in the 21st century has transformed the global economic, cultural and technological landscape, but it has also created serious environmental challenges, particularly air pollution. According to the data from the World Bank (2023), more than half of the world's population now lives in cities. The dense infrastructure and policy orientation have further accelerated urbanization. However, the air quality problems in urban areas are particularly severe. —Asian cities are disproportionately affected, with 99 out of the top 100 most polluted cities globally located in Asia (IQair, 2023), and PM2.5 concentrations in many regions exceeding the WHO's safe limit of 5 μg/m³ by 5-10 times. Industrial emissions, vehicle exhaust and high-density buildings contribute to the persistent accumulation of pollutants (e.g PM2.5, nitrogen dioxide and other harmful pollutants), that pose significant threat to public health. The worsening of urban air quality not only undermines human well- being but also deepens the sense of disconnection from nature.
The present study aims to identify and characterize the main Nature-based Solutions (NbS) that are being applied to mitigate the poor air quality in Asian cities, including Macao. Quantitative data collection and systematic literature review were carried out to identify and quantify the current effectiveness of NbS, examine their multi-scale functions, and ultimately provide evidence-based support for the development of sustainable cities. A survey conducted to assess the public awareness and acceptance of nature-based approaches for improving air quality in Asia, mainland China, and Macao.
The main findings ofthe literature review showed that the most common NbS used to improve air quality in cities are green roofs, green facades, and vertical gardens. These can enhance urban greening and mitigate air pollution through vegetation on roofs and facades, thereby contributing to improved the air quality in the cities.