thanksgiving weather of 1966 occurred in september 1969, but it passed without incident—neither smog nor deaths resulted. norman cousins, chairman of the mayor's task force, credited the regulations enacted since the 1966 smog for the prevention of a comparable september 1969 event. cousins wrote in a message to lindsay: new york city's air is cleaner and more breathable today than it was in 1966. ... it is important to ask what would have happened on those days if the pollution levels had continued to worsen at the same rate of deterioration that occurred from 1964 to 1966. the answer is that there could have been a substantial number of casualties. the fact that an episode did not occur attests to the capability of the city's programs to protect its air resources. after the passage of strict new state and federal air regulations, the city passed its updated air pollution control code in 1971, designed in part to address concerns that nitrogen oxides and unburned hydrocarbons had been left insufficiently controlled by the previous changes. by 1972, new york city had cut levels of sulfur dioxide and particulates by half from their peak. according to an article published by the epa journal in 1986, those improvements at the city level were "the legacy of concern that emerged after the 1966 thanksgiving day smog disaster." states' responses following the 1966 smog, air-pollution control became a major policy objective of both nelson rockefeller (left), the republican governor of new york, and lyndon b. johnson, the democratic president. prior to 1966, air-pollution control had largely been the responsibility of states and political subdivisions of states like counties and municipalities (cities and towns). the federal government played little role in air-pollution control, and to the extent that it did, its actions supported the efforts of states and local governments. for example, federal law provided resources like research, training, grants to improve state and local programs, and a conference procedure to convene agencies and polluters under the guidance of the department of health, education and welfare. direct regulations—such as, for example, setting emissions standards—were left to states. the governors of new york (rockefeller), new jersey (hughes), delaware (charles l. terry jr.), and pennsylvania (raymond p. shafer) met in december 1966 to address air pollution in their region. each governor pledged to enforce their state's pollution abatement laws and to prevent their own state from becoming a "pollution haven" with lax regulations to attract industry. at the same meeting, the governors also discussed the possibility of new tax incentives to motivate industry to reduce pollution and the creation of a new interstate compact to set industry standards, which would require adoption by all member states and approval by congress. those four states were already members of the delaware river basin commission (drbc), an interstate agency that controls water pollution in the delaware river. the proposed air-pollution compact was modeled after the drbc and would function similarly, setting minimum air standards across states and enabling enforcement actions against polluters. new york, new jersey, and connecticut adopted the proposed mid-atlantic states air pollution control compact with the possibility for delaware and pennsylvania to join in the future. its approval by congress became a policy goal of rockefeller's failed primary bid for the 1968 republican presidential nomination. the compact was never approved by congress and thus never took effect. after the 1966 smog, "the consequences of state inaction were apparent to the naked eye," public outcry intensified, and the demand for federal intervention increased. new jersey passed several new air-pollution laws in 1967. nevertheless, traffic and drifting polluted air from new jersey remained a major contributor to new york city's pollution problem. edward teller—the physicist known for his role in developing the hydrogen bomb and an advisor to mayor lindsay on pollution and energy issues—advocated for new york state to adopt stricter sulfur fuel standards than the city. a leader of the advocacy group citizens for cleaner air criticized the local and state governments at a state public hearing, calling the city's enforcement "in a state of collapse" and, saying the city acting alone "cannot or will not enforce any standard or rule," demanded that the state government increase its role. perhaps the most notable critic of new york's inaction was robert f. kennedy. on a 1967 tour of pollution sources, kennedy—then a new york senator and soon to embark on his 1968 presidential campaign—criticized the city, the states of new york and new jersey, industry, and the federal government for their failures to adequately address the problem. kennedy warned, "e are just as close to an air-pollution disaster as we were last thanksgiving." in kennedy's view, the solution would have to come from the federal government, as state and local agencies lacked the ability or oversight for the task. federal response air pollution control, already a priority of president lyndon b. johnson's administration, became a greater concern after the smog. by early 1967, his statements on air pollution became more rhetorically urgent. in january 1967, johnson sent a message to congress entitled "protecting our national heritage," the first section of which was entitled "the pollution of our air" and focused on the problems posed by air pollution. the message was prompted by wide public discussion of the problem following the 1966 smog. johnson cited the experiences of specific american cities and towns in the message, and highlighted the 1966 smog at length: two months ago, a mass of heavily polluted air—filled with poisons from incinerators, industrial furnaces, power plants, car, bus and truck engines—settled down upon the sixteen million people of greater new york. for four days, anyone going out on the streets inhaled chemical compounds that threatened his health. those who remained inside had little protection from the noxious gases that passed freely through cooling and heating systems. an estimated 80 persons died. thousands of men and women already suffering from respiratory diseases lived out the four days in fear and pain. finally, the winds came, freeing the mass of air from the weather-trap that had held it so dangerously. the immediate crisis was ended. new yorkers began to breathe "ordinary" air again. "ordinary" air in new york, as in most large cities, is filled with tons of pollutants: carbon monoxide from gasoline, diesel and jet engines, sulfur oxides from factories, apartment houses, and power plants; nitrogen oxides, hydrocarbons and a broad variety of other compounds. these poisons are not so dramatically dangerous most days of the year, as they were last thanksgiving in new york. but steadily, insidiously, they damage virtually everything that exists. president johnson signing the air quality act of 1967. the law, a series of amendments to the 1963 clean air act, was enacted in response to the 1966 smog. johnson called for a bill regulating toxins in the air and increasing funding for pollution programs. edmund muskie, a senator from maine and political environmentalist, praised johnson's words, pledged to hold hearings on the proposals, and would soon sponsor the johnson administration's bill, which became the air quality act. muskie also co-sponsored bills in 1967 for research on non-polluting automobiles using either electric or fuel cell technology. while discussing the research bills on the senate floor, muskie said "the serious air pollution situation in new york city dramatically illustrated what our cities may be facing in the future if an alternative to the combustion engine is not developed." congressional interest and public pressure for greater air pollution regulation had existed since the signing of the 1963 clean air act, the first federal legislation on the issue, but further action had been opposed by members of congress who believed responsibility for air regulation properly lay with the states, not the federal government. partly in response to the added public pressure spurred by the smog event, congress passed and johnson signed the 1967 air quality act, which amended the 1963 clean air act to provide for study of air quality and control methods. the air quality act was a significant advancement in the realm of air-pollution regulation, but one that was ultimately ineffective. in train v. natural resources defense council, inc., a 1975 decision by the supreme court of the united states, justice william rehnquist summarized the law's effect as follows: the focus shifted somewhat in the air quality act of 1967, 81 stat. 485. it reiterated the premise of the earlier clean air act 'that the prevention and control of air pollution at its source is the primary responsibility of states and local governments.' its provisions, however, increased the federal role in the prevention of air pollution, by according federal authorities certain powers of supervision and enforcement. but the states generally retained wide latitude to determine both the air quality standards which they would meet and the period of time in which they would do so. the response of the state to these manifestations of increasing congressional concern with air pollution was disappointing. even by 1970, state planning and implementation under the air quality act of 1967 had made little progress. among contemporaneous critics, john c. esposito—an environmentalist and affiliate of ralph nader—wrote the 1970 book vanishing air to accuse muskie of watering down the bill and adding needless complications to satisfy industry. a 2011 encyclopedia of environmental law article judged that the act "was a failure but it was the first step in federal air pollution control." calls for greater air pollution regulation in this era culminated with the passage under president richard nixon of the 1970 clean air act, which supplanted the air quality act and has been described as the most significant environmental legislation in american history. the 1970 clean air act significantly increased the role of the federal government and, for the first time, imposed air quality requirements on states. the 1966 smog in cultural memory the most widely recognized legacy of the 1966 smog was the political reaction to it, which galvanized the nascent environmental movement in the united states and prompted demand for sweeping air-pollution control laws. the smog has been remembered for various purposes by scientists, historians, journalists, writers, artists, activists, and political commentators. compared to the september 11 attacks a plume of smoke rising from lower manhattan after the september 11 attacks, seen from space. cumulative air pollution events like the 1966 smog contrast with the sudden pollution that resulted from the september 11 attacks. the full range of negative health effects arising from the september 11 attacks came to light in the years following the attacks. the 1966 smog serves, along with the earlier major new york city smog events in 1953 and 1963, as a precedent used for comparison with the air effects caused by the collapse of the world trade center. the 1966 smog and other historical smog events differ from the september 11 pollution in significant ways that limit their usefulness as a point of comparison. prior new york city smog events were chronic, cumulative, and caused by thousands of small sources, while the air impact of the september was sudden, intense, and the result of a single culpable source. the absence of prior events similar to the september 11 attacks left "a hole in the medical library," and presented medical experts with a challenge in the absence of "hard knowledge about the health consequences of intense brief pollution." compared to 21st-century smog in china the 1966 new york smog served as a historical precedent for air pollution in china in the 2010s (pictured is beijing in early 2013). other major air pollution, particularly in china, has been compared to the 1966 smog. elizabeth m. lynch, a new york–based legal scholar, said that images of visible air pollution in beijing from 2012 were "gross" but not "that much different from pictures of new york city in the 1950s and 1960s", specifically referring to the 1952, 1962, and 1966 smog events. lynch wrote that the chinese government's increased transparency on the issue was an encouraging sign that pollution in china could be regulated and abated, just as it had in the united states. similar comparisons between the 1966 smog and chinese pollution in late 2012 appeared in business insider and slate. usa today cited the 1966 smog after china issued its first "red alert" air quality warning in december 2015; the same