German carmakers Volkswagen, BMW and Daimler are already facing an onslaught of outrage by animal rights activists and environmentalists for emissions research they conducted on monkeys, but new reports from two German news outlets say the companies also financed human testing. The Süddeutscher and Stuttgarter Zeitung both reported on Monday that a research group funded by the auto industry giants tested the effects of gas nitrogen dioxide — a component of car exhaust — on "[25] healthy young persons." According to the paper, the European Research Association for Environment and Health in the Transport Sector examined participants at the University of Aachen "after inhaling NO2 at different concentrations for several hours each." In the end, the EUGT, which was disbanded in 2017, concluded that no health effects could be detected. Diesel emits more particulate soot than regular gasoline, as well as pollutants such as nitrogen dioxide and nitrogen oxides that in the short term, the EPAsays, can lead to respiratory ailments and exacerbate asthma. Revelations about the companies' experiments on people came just days after the New York Times wrote about similarexhaust inhalation tests they funded involving monkeys in the U.S. in 2014. The idea behind the test was to prove the newest diesel technology had solved diesel pollution problems. But the VW cars in the study used software that cheated on emissions. German Chancellor Angela Merkel called on the car manufacturers to immediately disclose the full extent of their scientific research, The Guardian reported. "These tests on monkeys or even humans are in no way ethically justified," said Merkel's spokesman Steffen Seibert. "The indignation felt by many people is completely understandable."The New York Times reports: