Strategies for healthy and sustainable transport
Many sustainable transport strategies to reduce climate change risks have large, immediate health benefits for the majority of the world’s population, and large equity benefits for vulnerable groups. Well-designed transport policies and infrastructure investment priorities can lead to far-reaching reductions in traffic-related health risks from air and noise pollution and injuries. Sustainable transport strategies in light of their potential to both mitigate climate change and achieve health gains, include:
- investments in, and prioritization of, rapid transit/public transport, such as rail, metro and bus;
- investments in, and prioritization of, transport networks for pedestrian and cyclists;
- compact land-use systems that increase density and diversity of uses featuring “15-minute self-sufficient neighbourhoods”;
- adoption of cleaner vehicular technologies;
- adoption of cleaner fuel technologies;
- efficient travel demand management.
Public transport
Shifting from private motorized transport to rapid transit/public transport, such as rail, metro and bus, is associated with a wide range of potential social, health and climate benefits, including:
- lower urban air pollution concentrations;
- lower rates of traffic injury risk;
- more physical activity and less obesity (public transport is often accessed by walking and cycling);
- reducing traffic congestion;
- less noise stress; and
- improved equity of access for people without cars.
Walking and cycling
Inclusion and improvement in the quality of pedestrian and bicycle paths protect walkers and cyclists and further encourages more people to walk and cycle, thereby promoting healthy behaviour. Other interventions targeting the built environment have been shown to enhance the appeal of physically active forms of transport.
Examples include:
- improvements in urban aesthetic features and attractiveness;
- decreased travel time between neighbourhoods;
- access to green and recreational spaces;
- bike-sharing programs;
- good lighting; and
- road safety.
Safe infrastructure for walking and cycling is also a pathway for achieving greater health equity. For the poorest urban sector who often cannot afford private vehicles, walking and cycling can provide a form of transport while reducing the risk of heart disease, stroke, certain cancers, diabetes, and even death. Accordingly, improved active transport is not only healthy; it is also equitable and cost-effective.
Vehicle technologies
Improved vehicles and technologies have helped mitigate some major health impacts of vehicle travel, namely air pollution and injury. For example:
- Lighter, more fuel-efficient vehicles that are driven at lower speeds are suggested to have injury reduction co-benefits.
- Bus fleet improvements, such as the inclusion of particle filters, low-sulphur diesel and the transition from diesel vehicles to compressed natural gas (CNG), electricity, or other alternative fuels significantly decrease harmful particle emissions.
- Hybrid, electric and gas fuel private vehicles also decrease local air pollution as well as noise pollution – although quieter vehicles can also create new injury risks and they do not support more physical activity.
While cleaner vehicle technologies are an important element of air pollution and climate mitigation, reducing reliance on private vehicles and motorized transport is as important, and can yield additional benefits to health, such as physical activity.
Fuel technologies
Diesel
Diesel emissions contain significant health-harmful particulate pollution and diesel exhaust has been identified as a carcinogen (IARC, 2013).
Although diesel fuel offers a slight climate benefit (in terms of CO2 emissions), this is offset by their proportionately higher emissions of black carbon, which is a component of particulate emissions (soot), and a powerful short-lived climate pollutant.
The Climate and Clean Air Coalition (CCAC) Heavy Duty Diesel Vehicles and Engines Initiative is pushing for major reductions in black carbon emissions through adoption of cleaner fuels and stricter vehicle regulations, particularly in developing countries and emerging economies where diesel fuel is often of a lower quality. The coalition has worked in Latin America and Asia to produce black carbon inventories, form national task forces and regional coalitions and to set target dates for improved national fuel standards.
Compressed natural gas
In comparison to diesel fuel, compressed natural gas (CNG) can reduce both carbon dioxide and particulate emissions, producing health and climate benefits. Many low- and middle- income countries have already adopted CNG bus and light-duty freight vehicle fleets, partly due to lower fuel costs.
The use of CNG for buses and taxis is now also being required as a means of reducing urban pollution emissions. While the ability of CNG to reduce pollution is highly dependent on the available technology, evidence suggests its use in the public transport and freight domains could lead to significant health benefits.
Biofuels
The use of biofuels in the transport sector has received much attention, yet the evidence is unclear on whether biofuels reduce health-relevant emissions and greenhouse gases. Certain biofuels, such as ethanol, can contain lower levels of black carbon and particulate emissions in comparison to gasoline– a benefit for health. However, the overall impact of biofuels on climate emissions and health may be very much dependent on the local context, including water, energy and chemical inputs required to grow or produce the fuel.
There are significant concerns regarding biofuels' production impacts on food security and nutrition of the poor. Biofuels derived from food sources or grown on land that could otherwise be used to cultivate food sources could lead to deforestation and threaten food security and food markets, especially in the world’s poorest regions.