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Environmental risks of diesel passenger vehicles in Brazil

Although Brazil has restricted the sale of diesel passenger cars since the 1970s, an auto industry lobby has been pressuring the government to lift the restrictions since 2013. While motor vehicle pollution contributes heavily to urban air quality problems in Brazil, this restriction has helped to limit some adverse impacts, 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 and have resulted in adverse human health impacts. Brazilian regulators should maintain restrictions on diesel passenger cars to avoid exacerbating air quality problems, harmful impacts on human health, and increased emission of climate pollutants. 
This analysis examines the environmental risks of the commercialization of diesel passenger cars in Brazil, including a potential increase in NOX and PM2.5 emissions, both of which contribute to poor air quality and negatively impact human health, as well as greenhouse gases and other species that contribute to climate change. The analysis concludes that, given current regulatory standards, the wide commercialization of diesel cars would significantly increase NOX and PM2.5 emissions, contributing to poor air quality and adding 150,000 premature deaths through 2050. Even a moderate rate of dieselization, with diesel vehicles representing about 15% of light-duty vehicle sales after 2030, could result in as many as 32,000 additional premature deaths through 2050. Furthermore, this analysis shows that the commercialization of diesel cars also would result in increased climate impacts due to additional emissions of carbon dioxide and black carbon.
Brazil is well-positioned to apply lessons learned from the international regulatory experience. The U.S. provides the strongest example of effective motor vehicle emissions control, including fuel-neutral vehicle emission standards with strict limits and representative test cycles, as well as a strong in-use compliance program. European particle number standards offer additional protections to ensure that the best filter technology is employed. However, Europe continues to suffer from high PM emissions from the large fleet of pre-Euro 5 diesel vehicles. EU standards still have not adequately addressed NOX emissions from diesel vehicles, although current proposals to strengthen in-use compliance represent a positive step to control diesel emissions and address air quality problems.
In order to reduce the environmental and health impacts of the transportation sector, Brazilian regulators should learn from these international best practices and take the following actions:
  • Adopt stringent vehicle emission standards to ensure that diesel vehicles are equipped with particle filters and to protect against the worst health and air quality impacts of diesel vehicles. These standards should be equivalent to either U.S. Tier 2 or Euro 6 standards.
  • Phase out 500-ppm diesel outside metropolitan areas to avoid the risk of misfueling and damaging aftertreatment control systems.
  • Implement an effective in-use compliance and enforcement program, complete with real-world testing, to ensure that real-world NOX emissions from diesel vehicles are adequately controlled under certification limits.
Until new stringent vehicle and fuel standards are in place and shown to be effectively controlling both PM and NOX emissions from diesel vehicles, any decision to lift diesel car restrictions would run counter to environmental and health goals.