Testing the dirty diesels too

The new head of Secretariat of the Environment and Natural Resources (SEMARNAT), Rafeal Pacchiano Alamán, has announced that Mexico will undertake a real-world, in-use testing program for diesel vehicles. The ICCT will serve as an advisor and work with Mexico Petroleum Institute (IMP) to design and implement the program and analyze the test results. We wholeheartedly support the government’s action: if the VW episode has demonstrated anything clearly it is that this type of real-world testing needs to happen all over the world and can both help guard against blatant violations of standards and bring focus on narrowing the gap between the laboratory and real-world—which we have seen for both the pollutants that harm health and those that threaten the global climate.

Unfortunately, we don’t need any tests at all to know that the Euro 3 and 4-equivalent diesels sold in Mexico are certified to have three to eight times higher NO_x emissions than the gasoline vehicles sold. And, unlike the gasoline vehicles sold, which are typically over complying with standards, the real-world NO_x emissions tests are likely to demonstrate again in Mexico the much greater gap that has been seen routinely for vehicles certified to the European NEDC test cycle. Worse, deadly particulate emissions are almost 50 times higher than the emissions from gasoline vehicles. This is because the standards in place do not require advanced aftertreatment controls for diesels, neither particulate filters nor any kind of NO_x controls, and they allow diesels to meet less stringent standards than gasoline vehicles. A portion of VW’s diesels sold in Mexico come from India, where lax standards combined with diesels making up more than half of sales are adding to an air-quality problem worse than China’s.

Luckily for the citizens of Mexico, SEMARNAT has plans to change this and to fix the standards while diesels are still a tiny portion of new vehicle sales. SEMARNAT announced in April a plan to harmonize emissions and greenhouse gas standards with the rest of North America. Canada has already adopted the fuel-neutral US Tier 3 standards, the most stringent light-duty vehicle standards in the world (aside from California’s LEV III standards, which are ever-so-slightly more stringent), and the US greenhouse gas standards out to 2025, which are very similar in ambition to the European standards (although real-world vehicle CO₂ emissions in Europe are, as we’ve been showing for the past several years, much higher than the official numbers, and trending upward annually).

Harmonizing within North America has a lot of advantages for Mexico. The market is well integrated—the great majority of vehicle models sold in Mexico are already available in the US or Canada, and Mexico is also a large and growing exporter to the US market. More importantly, US standards meet Mexico’s needs. Allowable evaporation of hydrocarbons from European gasoline vehicles is 20–30 times higher than from US-certified cars, and evaporative emissions are a huge contributor to Mexico’s serious ozone problem. The US, and California in particular, has been a global leader for on-board diagnostics (OBD). The US OBD requirements are more demanding than Europe’s, and setting a single OBD specification will permit Mexico to implement better and cheaper inspection and maintenance programs, as well as potentially allowing testing at the border to block importation of high-emitting vehicles. But perhaps the most important benefit to Mexico is that it can ride on the coattails of EPA and ARB’s certification and compliance programs—already the best in the world, and about to get even better.