Government emissions tests have drastically underestimated the pollution created by diesel trucks, cars and other vehicles, according to a study published this week in Nature. Instead of the previously estimated 9.4 million tons of emissions worldwide, researchers calculate the actual amount was 5 million tons higher, saying the discrepancy comes from not testing vehicles under real-world conditions. The study estimates the added soot and smog could be responsible for an additional 38,000 deaths a year from heart and lung diseases. Most of those added deaths would be in the EU, China and India, which have a higher proportion of diesel vehicles. Ironically, the study comes at a time when one lab that could help better understand diesel emissions, the EPA’s National Vehicle and Fuel Emissions Laboratory, faces severe budget cuts under President Trump’s budget plan.