Coincidence or not, while Brazilians are distracted by the impeachment of President Dilma Rousseff, other political turmoil, economic recession, the upcoming Olympics, and the Zika virus, a Chamber of Deputies committee—yep, there are still some working—has proposed a law (PL 1013/2011) to allow diesel cars in Brazil. This was always a terrible idea, as we pointed out here, and the drumbeat of news about pollution from diesel cars in Europe and the US makes it seem worse all the time.
Diesel vehicles have been restricted in Brazil since the 1970s, to reduce dependence on imported oil. To be precise, what's restricted is the sale of diesel fuel for use in vehicles with payload capacity (passengers plus cargo) below a certain weight, but the effect has been to limit sales of passenger cars, since you couldn't (in principle) buy fuel for them. Nevertheless, diesel technology has entered the Brazilian passenger market through technical loopholes. Because the fuel restriction applied to vehicles with payload capacity less than 1,000 kg, some sport utility vehicles and pick-up trucks entered the market as light commercial vehicles. Diesels already represent 6% of sales of light-duty vehicles (cars and light commercial vehicles), and 16% of light commercial vehicles, many of which are used for passenger transportation.
Ironically, two days before the U.S. Environmental Protection Agency (EPA) and the California Air Resources Board announced that Volkswagen had installed defeat devices on diesel cars in the U.S., a Brazilian government committee was formed to consider lifting the restriction on the sale of diesel fuel to cars. Volkswagen subsequently admitted to installing defeat devices on 11 million cars worldwide, including the Amarok in Brazil. Now, even as the international media shines an increasingly harsh spotlight on the poor environmental performance of diesel cars, and many government agencies worldwide struggle to control diesel emissions or ban diesels altogether, that committee has proposed to lift all restrictions on the sale of diesel to cars.
Diesel cars are a terrible idea in Brazil for economic, environmental, and public health reasons. Brazil imported 19% of all diesel fuel sold in the country in 2014, and increased demand will mean importing even more, and worsening the country's trade deficit. More demand for diesel for cars would also drive up overall demand and compete with freight and public transit. From an environmental perspective, a larger number of diesel engines on the road could exacerbate climate change, because diesel fuel would displace some amount of ethanol, which has clear climate benefits over diesel. Gasoline in Brazil is currently a 27% ethanol blend (E27), and virtually all new cars in Brazil are flex-fuel, meaning they can burn either gasoline or pure ethanol (E100). Depending on the sales of diesel cars, carbon dioxide (CO2) emissions could increase between 5% and 22% in 2050.
However, the most concerning impacts of diesel cars would be on air quality and public health. Although diesels make up about 6% of new LDV sales in Brazil, we estimate that they account for about 30% of nitrogen oxides (NOX) emissions and 65% of fine particle (PM2.5) emissions from new LDVs, two of the most harmful pollutants to human health. Any increase in the number of diesel cars on the roads would exacerbate this problem.
In Europe, where diesels make up about half of the car fleet, they emit on average about seven times more NOX in real-world conditions than the regulatory limit. And, as the results of post-VW testing programs in Germany, the UK, and France show, the problem is by no means limited to a single manufacturer or a small number of models. With respect to fine particle emissions, classified as a human carcinogen by the World Health Organization (WHO), certification limits of a new diesel car sold in Brazil today would be almost 30 times greater than a new gasoline-ethanol flex-fuel engine. We estimate that rising sales of diesel cars in Brazil to levels equivalent to Europe’s could result in 150,000 premature deaths through 2050 because of exposure to diesel PM2.5 in urban centers.
The restriction on diesel cars has helped to limit their adverse impacts in Brazil, especially compared to regions such as Europe or India where policies supporting widespread dieselization combined with lax emission standards have contributed to severe air quality problems. Nevertheless, despite progress resulting from PROCONVE, Brazil’s program to control vehicle emissions, air quality in many Brazilian cities still does not comply with WHO guidelines. Expanding the market for diesel cars will only make that problem worse.
Before considering lifting restrictions on diesel cars, Brazilian regulators should adopt stringent vehicle emission standards (equivalent to either U.S. Tier 2 or Euro 6 standards) and completely eliminate diesel fuel with more than 500 ppm sulfur content (still sold outside metropolitan regions) from the national fuel supply to protect against the worst health and air-quality impacts of diesel vehicles. Regulators should also learn from the unfolding crisis over excessive real-world emissions in Europe and implement an effective in-use compliance and enforcement program, to ensure that emissions from diesel vehicles under normal driving conditions remain at or near the regulatory limits. Until stringent vehicle and fuel standards are shown to be effectively controlling diesel emissions, lifting diesel car restrictions would run counter to environmental and health goals.