After assessing the flow of traffic on São Paulo’s highways, researchers calculated the possible effects of substituting diesel oil by liquid natural gas

The full substitution of diesel oil used as fuel in heavy-duty trucks by liquid natural gas (LNG) would save lives but would not be enough to avoid most of the deaths now attributed to be an effect of air pollution is the conclusion of a study performed by researchers of the University of São Paulo (USP) and the United Kingdom’s Imperial College London. The research project was published in the magazine Atmospheric Environment and states that LNG helps reduce emissions of particulate materials but is not sufficient for avoiding all the deaths attributed to air pollution in the cities along the highways that were studied.

To arrive at this conclusion, the researchers surveyed the flow of trucks between São Paulo and Campinas on the Anhanguera-Bandeirantes highway system. Then they estimated the pollutants emitted by the cargo vehicles, while assessing the dispersion into the atmosphere of particulate materials, especially the concentrations of MP10 and MP2.5. Furthermore, statistics were gathered regarding deaths due to lung cancer and cardiovascular and respiratory diseases in 12 cities neighboring on the highways, taken from the DATASUS database (Informatics Department of the Brazilian Unified Public Health System). The methodology of the World Health Organization (WHO) was used to also estimate the possible number of deaths avoided by changing the fuel.

The places having the greatest concentration of pollutants, according to the study (which only looked at emissions from trucks), are to be found in Jundiaí, near Bandeirantes highway, and in Cajamar, near Anhanguera highway. The lowest concentration was found in Campinas, at a point located at a distance from both highways.

According to the studies analyzed in the article, vehicles powered by natural gas produce 70% to 85% less pollutants than gasoline and diesel and cause a 10% reduction in greenhouse gas (GHG) emissions, compared to trucks running on diesel fuel. Therefore, it would seem to be natural to find a correlation between deaths and air pollution.

But, to the surprise of the researchers, the impact of the change in fuel, as shown by the models used in the study, was less than expected. “We thought that there would be a greater reduction in deaths attributable to air pollution caused by heavy-duty cargo vehicles,” states Ana Carolina Rodrigues Teixeira, of USP’s Institute of Energy and Environment (IEE), who was the article’s lead author. “In the case of respiratory deaths in children, for example, there would be no reduction in deaths after fully substituting diesel fuel by liquid natural gas in the trucks. That is, we need to evaluate other sources of pollution, like passenger and industrial vehicles, to better understand what the impact would be on public health of reducing the emission of pollutants.”

The researchers calculated that annual death rates for cardiovascular disease attributable to atmospheric pollution could vary between 8 and 296 deaths, with an approximate average of 188. For respiratory illnesses in the elderly, the variation is from 52 to 190 deaths and for lung cancer it is from 18 to 62 deaths for the year 2016. The simulation showed that a change in truck fuel to liquid natural gas could avoid less than five deaths per year from lung cancer. As for cardiovascular diseases, the maximum reduction could be 14 deaths, but with a 90% chance that less than five deaths would be avoided. For respiratory illnesses in the elderly, less than 10 deaths would be avoided per year.

Blue Corridor – The study was carried out within the scope of a project of the FAPESP-Shell Research Centre for Gas Innovation (RCGI) and concluded on November 30, 2020, for the purpose of assessing the viability of implementing a Blue Corridor in the State of São Paulo; this concept provides for the implementation of infrastructure for using natural gas as fuel in heavy-duty highway vehicles. The objectives of the project included: defining the location of the Blue Corridor; places and forms of supply; and incentive policies and strategies for implementing the Corridor. Also assessed were the variations in local emissions of pollutants and of greenhouse gases arising from the change of diesel oil for liquid natural gas to fuel the trucks, as well as possible impacts on human health.

According to Teixeira, this phase of the study has its limitations, because it does not take into account, for example, the age of the vehicles circulating on the highways, which is one of the factors that can impact the quantity of pollutants emitted, and it did not analyze the health-related microdata regarding of the municipalities bordering on the highways.

“We see this study as the kick-off for the discussion of public policies related to the subject,” she says. “Efforts are needed, not only on the side of the heavy-duty truck transportation sector, which sometimes is criticized because of its high emission levels, but also of other sectors,” she concludes.

The summary of the article “PM emissions from heavy-duty trucks and their impacts on human health” can be seen at this link: https://www.sciencedirect.com/science/article/abs/pii/S1352231020305483