International Day of Clean Air for Blue Skies
Motorised transport in urban areas—particularly the widespread use of private cars—significantly contributes to climate change through carbon emissions and air pollution. Air pollutants including airborne particulate matter are linked to serious health effects, including respiratory and cardiovascular diseases, as well as cognitive impairments. Environmental factors such as rising urban temperatures due to global warming, and limited access to green spaces, further aggravate these health risks.
In addition, reliance on sedentary forms of transport increases the risk of obesity and chronic illnesses. In contrast, active travel—such as walking and cycling—can improve physical and mental health, reduce greenhouse gas emissions, and help mitigate air pollution. Non-motorised transport also brings economic and social benefits, making it a key component of a more sustainable urban future.
This shift toward people-centred mobility aligns with the World Health Organization’s Global Action Plan on Physical Activity. Cities known for high levels of active mobility, like Amsterdam and Copenhagen, serve as models of liveability—though they are located in temperate regions, similar transformations are feasible in tropical cities as well.
However, urban infrastructure in many tropical regions tends to prioritise motor vehicles, creating environments that are often unsafe and inconvenient for pedestrians and cyclists. Poor route connectivity, inadequate planning, and insufficient monitoring of pedestrian and cycling paths further hinder active travel.
Cultural attitudes also present a barrier. In many societies, cars are seen as status symbols, while walking and cycling are stigmatised as lower-status forms of transport. Cyclists and pedestrians are frequently viewed as obstacles by drivers, further undermining their safety in car-dominated urban design.
To overcome these challenges, a transformative shift is needed in transport policies, urban planning, infrastructure development, and enforcement. Cities must put people—not cars—at the centre of mobility decisions. Only then can active transport become a viable, attractive, and widely adopted choice for urban residents.
Tenured professor in Civil and Environmental Engineering at NUS, focusing on air quality, climate change, and public health. He is recognized among the top 100 scientists in Asia and is an elected Fellow of several prestigious scientific societies. He also serves as Editor for Aerosol and Air Quality Research and is on the editorial boards of international journals such as Atmosphere and Scientific Reports. Prof Bala, a resident of Singapore, incorporates active mobility into his daily routine.