1952 Dr. Arie Haagen-Smit, from the California Institute of Technology, discovers the nature and causes of photochemical smog determining that a major component of "smog" is ozone created by the interaction of nitrogen oxides (NOx) and hydrocarbons (HC). This breakthrough discovery, which explains the grey-brown haze in Los Angeles area and other metropolitan cities, becomes the foundation upon which pollution control standards will be based.
1963 U.S. Clean Air Act of 1963 is passed as the first federal clean air legislation setting emissions standards for stationary but not yet mobile sources. Tests, however, show that automobiles account for 70 percent of HC emissions and 60 percent of NOx emissions.
U.S. Congress budgets $95 million for study and cleanup efforts at local, state and federal level.
1965 U.S. Motor Vehicle Air Pollution Control Act (amendments of the Clean Air Act) sets first federal emission standards for reduction in HC and CO for automobiles beginning with 1968 models. Automakers modify engines to meet standards but decline in emissions is not satisfying. Although catalytic converters are already invented, their durability is still severely limited due to high lead content in fuel.
Hearings on leaded gasoline begin in U.S. Senate and UCLA scientist Clair Patterson's study "Contaminated and Natural Lead Environments of Man" offers first hard proof that high lead levels in industrial nations are man-made and endemic.
1967 California Air Resources Board (ARB) is created from the merging of the California Motor Vehicle Pollution Control Board and the Bureau of Air Sanitation and its Laboratory.
ARB (which today is viewed as one of the most successful pollution programs in the world) is established to: attain and maintain healthy air quality; conduct research into the causes and solutions of air pollution; and systematically attack the serious problem caused by motor vehicles, which are the major causes of air pollution in California.
Federal Air Quality Act of 1967 is enacted. Establishes framework for defining "air quality control regions" based on meteorological and topographical factors of air pollution.
1970 First “Earth Day” in U.S. celebrated by an estimated 20 million people nationwide, putting environmental concerns on the national agenda
Environment Protection Agency (EPA) established by the Administration as an independent agency to coordinate all new environmental initiatives in the U.S.
U.S. Clean Air Act of 1970, a major revision of the 1963 Clean Air Act, requires automobile emissions of HC, CO and NOx to be reduced by at least 90 percent. Automakers realize that engine modifications not successful in meeting tighter standards and opportunities for catalytic converters grow. IPA Members Engelhard, Johnson Matthey and the precious metals division of Umicore (then Degussa) researching and developing catalytic converters to meet emissions requirements. Platinum-rhodium and platinum-palladium-based catalyst prove superior to other metals.
1971 EPA defines, for five of the most common air contaminants - sulfur dioxide, particulate matter, carbon monoxide, photochemical oxidants, and nitrogen dioxide - the levels at which "significant harm" to the health of persons might occur during episodes of high air pollution
IPA Member Johnson Matthey files patent covering use of a rhodium-promoted platinum catalyst to control NOx and gaseous compounds
1972 Corning Inc. develops ceramic substrate for use in catalytic converters. Production of bricks or “monoliths” with honeycomb structures that have sufficiently high melting points and thermal durability to withstand tough operating environments is now possible. Platinum group metals (PGMs) applied to substrate to clean emissions. Corning brings their ceramic substrate innovation to market in 1974.
Although the substrate is the size of a soda can, Corning and others realize that by increasing the surface area of the substrate by increasing the cell densities per square inch (cpsi) would quicken reactions. Ceramic monoliths with up to 400 cpsi and higher were introduced and today’s substrate, with as many as 900 cspi, has an effective area compared to a football field.
IPA Member Johnson Matthey proves to the EPA that US emissions regulations can be met using rhodium-platinum catalysts.
1974 First fuel economy goals, known as corporate average fuel economy (CAFE) standards, for automobiles set in the U.S. starting with 1975 models. These standards would be established under the Energy Policy and Conservation Act of 1975.
Corning ships first catalyst substrate to autocatalyst manufacturers for use on 1975 models.
1975 EPA finds that leaded gasoline seriously degrades the functioning of catalyst emission control systems. A catalyst-equipped vehicle that has been continuously operated on leaded fuel is presumed, EPA says, to no longer be in compliance with Federal emission standards.
EPA announces that working catalysts are required on all imported cars: Any American or foreign automobile that has a catalytic converter and has been driven outside the United States, Canada and Mexico (where unleaded gasoline is not generally available), will have to be fitted with a new catalytic converter before it can be imported into the United States.
1976 IPA Member Engelhard introduces the first “three-way” automotive catalyst. The “three-way catalyst” could simultaneously oxidize CO and HC to carbon dioxide and water while also reducing NOx to nitrogen. Prior to the “three-way” technology, catalysts were only able to reduce CO and HC.
Japanese vehicle emissions standards come into effect to control HC, CO and NOx as pollution in Tokyo and other metropolitan areas increases.
1978 U.S. Department of Transportation and EPA announce joint effort to help cities improve air quality through transportation planning.
1985 EPA sets new limits on lead in gasoline cutting the amount used in gasoline by 90 percent starting 1986.
1990 U.S. Clean Air Act Amendments of 1990 requires greater reductions in HC, CO, NOx and particulate emissions from 1994 onwards. Government encourages the use of low-sulfur fuels as well as alternative fuels as a means of reducing sulfur dioxide in the atmosphere.
20th anniversary of Earth Day sees 140 nations celebrating.
1991 New legislation in Japan sets more stringent NOx emissions limits.
1993 European Union emissions regulations come into effect requiring the use of catalytic converters for the first time (Euro 1).
EURO 1 to 4 are emissions standards for motor vehicles stipulated by the European Union. They determine limits for the pollutants contained in exhaust gas: sulfur dioxide, oxides of nitrogen, hydrocarbons, carbon monoxide, carbon dioxide and particulates (diesel).
1994 U.S. Clean Air Act Ammendments of 1990, also known as Tier 1, phased in.
1996 EPA finalizes leaded gas ban.
European Union phases in Euro 2 standards, tightening emissions legislation further.
California Low Emissions Vehicle (LEV) standards introduced emphasizing the cold start control of emissions; palladium-based catalysts found to be particularly suited to controlling HC emissions on engine start-up.
The World Bank joins the World Health Organization and others in calling for global phase-out of leaded gasoline reporting that health costs of leaded gasoline are far higher than the benefits to a few refiners and gasoline distributors.
1997 The Kyoto Protocol, a legally binding international agreement to reduce greenhouse gas emissions causing climate change, is negotiated during the CoP-3 meeting held Kyoto, Japan. Kyoto Protocol adopted by U.S. and 121 other nations, however not ratified by U.S. Congress.
1999 EPA finalizes Cleaner Cars and Fuels Standards, reducing tailpipe emissions as much as 95 percent and applying the same stringent standard to cars and to sport utility vehicles, including the largest models, and cutting the sulfur content of gasoline by up to 90 percent.
National Low Emissions Vehicle (NLEV) emissions standards take effect in the U.S., requiring very substantial reductions in NOx.
2000 EPA endorses Cleaner Diesel Fuel Program proposing to dramatically reduce the amount of sulfur presently in diesel fuel in order to create the cleanest running heavy-duty trucks and buses in history.
EU emissions standards for all road vehicles become more stringent with introduction of Euro 3 regulations.
European Union bans leaded gasoline.
2001 European announces Commission communication of "The Clean Air for Europe (CAFE) Programme: Towards a Thematic Strategy for Air Quality", which aims by 2005 to develop a long-term, strategic and integrated policy advice to protect against significant negative effects of air pollution on human health and the environment.
In 2001, it became compulsory for all new vehicles to comply with the limits of Euro 3. From January 2006, all cars will have to at least fulfill the Euro 4 emissions standard. The successive regulations each represent an approx. 50% tightening of emission limits compared with the previous stage.
2003 Tokyo and surrounding regions impose strict particulate matter limits for heavy-duty diesel vehicles requiring retrofitted catalyzed particulate filters.
Visit Japan’s Ministry of the Environment Web site to read more about Environmental Protection Policy in Japan.
2004 Phase in of US Tier II emissions standards begins, mandating further large reductions in NOx and particulate matter emissions.
EPA releases report showing emissions of the six principal pollutants identified in the Clean Air Act dropped again in 2003, signalling that America's air is the cleanest ever in three decades. To read EPA's report "Clean Air Status Report - Three Decades of Progress" goto EPA's Web site and download PDF here (3MB).
2005 As more stringent emissions legislation continues to be introduced, catalytic converters and diesel particulate filters will become increasingly important for emissions control in the transportation industry, and on other off-road hydrocarbon-burning engines (lawnmowers, chainsaws, etc.).
For more information on current and future emissions legislation in the U.S., EU or Japan please visit:
Environmental Protection Agency (EPA)
http://www.epa.gov
European Commission Environment Web site
http://europa.eu.int/comm/environment/index_en.htm
Japanese Ministry of the Environment
http://www.env.go.jp/en/pol/index.html
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1950 through 1969 
