Currently, the world’s transportation systems rely on burning fossil fuels, contributing to alarming amounts of air pollution and 14% of total global greenhouse  gas emissions (GHG). With continued urbanization, especially in Africa and Asia, emissions are continuing to rise, exacting a toll on human health and our environment. Indeed, one recent study estimates that in 2012, 10.2 million global excess deaths could be attributed to fine particulate matter from carbon combustion; transportation is a major source of pollution including particulate matter in almost all of our cities with these pollutants coming from both vehicle exhaust but  also from tires. 

Given that transport modes  such as motorcycle taxis, rickshaws and minibus systems are dominant in the rapidly urbanizing cities of Asia and Africa, how to move towards clean, green “popular” transport is a pressing, but much neglected, health and environmental justice issue. These transport modes and systems are ‘popular’ in the sense that they are widely used and developed bottom up through privately or cooperatively run efforts to provide shared mobility. Sometimes called paratransit or informal transport, these efforts aim to fill gaps created by grossly inadequate investment in public transport, are a form of transit (not para-transit) and are widely entrenched, often paying formal licenses and fees; informalities that emerge in relation to these systems such as the need to create an ad hoc bus stop or route or pay a bribe to police are not intrinsic characteristics of these systems but produced by state and planning failure in the transport sector, hence I prefer the term popular transport. Across the globe, these popular modes allow cities to function and generate critical access and employment for a large number of workers. 

Besides being linked to high numbers of crashes, popular transport modes are often highly polluting. Their regular use means large numbers of passengers and workers are exposed to high levels of pollution with serious health impacts including cardiovascular and respiratory illnesses. For example, two-stroke motorcycles and auto rickshaws which are popular because of their accessibility and ability to circumvent traffic, can emit more pollution per mile than passenger cars. Minibus systems, widely used in most cities, often rely on modified  fuels and old, poorly maintained vehicles, part of a used vehicles recycling economy that some argue shifts serious emissions from North America and Europe to Asia or Africa. Given that the poorer segments of urban populations tend to use these modes, improving these systems for safety- which includes reducing disease-causing emissions- is an important environmental justice issue.

On a per capita basis, these popular modes most likely still generate less emissions than private vehicles. However, we have not adequately researched emissions from popular modes,  and a great deal of data is missing, most likely meaning current transport contributions to emissions inventories for many metropolitan areas are inaccurate. While some existing efforts to quantify informal transport emissions exist, these emissions are not always disaggregated carefully to allow us to isolate the total contribution from popular or “informal”  transport even though this is critical for policy purposes. To address the complex set of issues around popular transport emissions, it is critical to properly measure pollutants from these modes and understand their specific contributing share to national and local GHG inventories and health and equity impacts of this pollution.

Currently, a paradigm shift is underway; a movement away from a replace and displace approach to popular transport towards an embrace and improve strategy.  Increasingly, popular modes are understood as being first and last mile connectors to much needed mass transit investments from BRT to rail and key to making them function well, helping to reduce our transport emissions. Evidence also exists that actors working in popular transport are already taking up clean energy innovations from electrification to leveraging technologies to improve operations and service. This makes it more attractive for residents to use more efficient and decongesting  shared mobility modes, reducing individual car use and making cities more liveable and healthy. If we wish to make headway on our intertwined health, equity and environmental challenges related to transport emissions, we will need to embrace creative data-driven strategies with the popular transport sector. A move towards clean, green popular transport is an important part of building  higher quality public and mass transport worldwide and reducing our emissions and  their devastating consequences.