May 3, 2018

PRESS RELEASE

Choice of fuel in the fleet of heavy-duty vehicles such as buses and trucks has major impact on air pollution and population health, shows study on recent experience in São Paulo, Brazil.

A study published by the Journal of the European Economic Association, one of the leading academic journals in economics, shows that the removal of 20,000 trucks using diesel oil in the streets of São Paulo significantly reduced: (i) air pollution, (ii) hospital admissions, and (iii) the number of cardio-respiratory deaths. The removal in 2010 of these heavy-duty vehicles from the capital's roads was made possible by the inauguration of the southern section of a beltway constructed to divert traffic from the inner city, as well as changes in the truck rotation system. Also relevant to the public administration, the reduction in traffic congestion - which had been the main motivation of the beltway and the truck rotation - was only temporary, with the general increase in the use of vehicles, mainly light vehicles based on gasoline and ethanol.

The positive health outcomes of the intervention could guide the formulation of similar transport polices in other megacities, where humans and diesel vehicles reside and transit in close proximity

In densely populated cities like São Paulo, many vehicles running on diesel such as commercial trucks, vans and buses circulate right by where people live, causing them to be constantly exposed to high levels of diesel emission. It is critical to manage diesel emission in these cities as diesel emits highly polluted particulate matter and nitrogen oxides that increase the risk of respiratory and cardiovascular disease, among other illnesses.

Health outcomes of São Paulo’s beltway 

In 2010, São Paulo constructed a beltway along sparsely populated areas that are 25 kilometers away from the city centre. The original intent of building the beltway was to enable heavy-duty vehicles to bypass the densely populated neighborhoods, and thereby ease traffic congestion in the inner-city roads.

While the intervention did immediately relieve road congestion by 20 per cent, the researchers found that the effect was short-lived as passenger cars quickly replaced the inner-city road space, which the heavy-duty vehicles had left behind. However, the researchers also found that the replacement of heavy-duty diesel vehicles with gasoline-ethanol passenger cars on the inner-city roads resulted in a sustained drop in the level of nitrogen oxides in the air, reducing air pollution in the city even after the traffic congestion rebounded.

The improved air quality in São Paulo also translated into long-lasting positive health outcomes for its residents. The researchers observed that the compositional change in traffic in the inner-city roads resulting from the beltway’s diversion of diesel vehicles led to an overall estimated reduction of 5,000 hospital admissions associated with respiratory and cardiovascular illness every year. The researchers quantify about one annual premature death for every 100-200 diesel trucks using inner-city roads.

A lesson for local and regional transport policies

Alberto Salvo, a Brazilian economist at the National University of Singapore (NUS) and one of the authors of the study, commented "we use São Paulo as a real-world laboratory, but the immediate exposure to diesel fuel burn by the urban population occurs in many cities in Brazil and abroad, in Latin America, Europe and Asia. Our study quantifies the benefit to the urban population when its rulers exchange diesel in the bus fleet for cleaner energies, such as natural gas. "

Nelson Gouveia, a professor at the University of São Paulo Medical School and also author of the study, adds: "It is important to show that interventions in urban mobility have a significant impact on the health of the population"

The study also included the biostatistician Jiaxiu He, a researcher at Western University in Canada.

The research was funded by the Initiative for Sustainability and Energy of Northwestern University, USA, as well as the Academic Research Fund Tier 1 (FY2013-FRC3-003) of the Ministry of Education in Singapore.

The study “External Effects of Diesel Trucks Circulating Inside the Sao Paulo Megacity” was published in the Journal of the European Economic Association on 27 April 2018 and is available on the website of the Journal.

Contact for information:
Nelson Gouveia, ngouveia@usp.br
Alberto Salvo, albertosalvo@nus.edu.sg