Starting June 10, 1968, the Japanese Government passed the () which regulated all sources of air pollutants. As a result of the 1968 law, dispute resolutions were passed under the 1970 (). As a result of the 1970 law, in 1973 the first installment of four sets of new emissions standards were introduced. Interim standards were introduced on January 1, 1975 and again for 1976. The final set of standards were introduced for 1978. While the standards were introduced they were not made immediately mandatory, instead tax breaks were offered for cars which passed them. The standards were based on those adopted by the original US Clean Air Act of 1970, but the test cycle included more slow city driving to correctly reflect the Japanese situation. The 1978 limits for "mean emissions" during a "Hot Start Test" of CO, hydrocarbons, and NOx were of CO, of HC, and of NOx respectively. Maximum limits are of CO, of HC, and of NOx. One interesting detail of the Japanese emissions standards was that they were introduced in a soft manner; that is, 1978 model year cars could be sold that did not meet the 1978 standards, but they would suffer various tax penalties. This gave manufacturers breathing room to properly engineer solutions and also incentivized fixing the best-selling models first, leading to smoother adoption of clean air standards and fewer drivability concerns than in many other markets.