The Netherlands' official automobile inspector TNO, on behalf of the Dutch Minister of the Environment, conducted an on-road tests of a C-Class Mercedes C220 CDi BlueTec diesel and determined it emitted more than 40 times the amount of cancer-causing NOx than in the lab test. The tests were done at temperatures below 10 degrees Celsius (50 °F). Mercedes says it is permissible for the BlueTec engine to emit 40 times more NOx when the temperature is less than 10 °C (50 °F).