Germany has often balked at efforts to tighten regulations on auto emissions and to improve enforcement. On Tuesday, the European Commission reiterated its intention to pursue legal action against Germany and eight other European Union countries for their chronic failure to enforce air quality standards.
Karmenu Vella, the European commissioner responsible for environmental matters, met with ministers from the nine offending countries in Brussels on Tuesday and said afterward that they had failed to present credible plans for reducing pollution.
Mr. Vella said 400,000 people in the European Union died prematurely each year as a result of air pollution from all sources “because of a massive, widespread failure to address the problem.” He expressed frustration that “a sense of urgency is not always evident across member states.”
The experiments that preceded Mr. Steg’s suspension were conducted at a laboratory in Albuquerque for the European Research Group on Environment and Health in the Transport Sector, known by its German initials, E.U.G.T.
Although ostensibly independent, the organization was financed entirely by Volkswagen, Daimler and BMW.
The experiments — carried out in 2014, a year before Volkswagen was caught using software to cloak excess diesel emissions — involved exposing a group of monkeys to exhaust from a late-model diesel Volkswagen; a second group of monkeys was exposed to exhaust from an older Ford diesel pickup truck.
After breathing diluted exhaust for four hours, the monkeys were examined for signs of lung inflammation or other ill effects. The research did not kill the monkeys, but it was unclear what happened to them afterward the experiments were completed.
The experiments also provided another example of how Volkswagen used software to conceal emissions of nitrogen oxides that were far above limits allowed by law. The Beetle provided by Volkswagen for the tests had been fitted with software that caused it to produce far less pollution in the lab than it would have produced on the road. In other words, the results were deliberately manipulated.
Results of the research had not been published by the time the E.U.G.T. folded last year.