Many view the first Earth Day in 1970 as a cultural and political landmark without which we might not have had the Clean Air Act amendments of 1970, the Clean Water Act of 1972 or the Endangered Species Act, to name just a few pieces of environmental legislation. But before there was an Earth Day, America’s air was becoming cleaner, water-related diseases had been virtually eradicated and, habitat loss, the major threat to species, had been reversed.

Between 1957 and 1970, particulate matter concentrations in urban areas declined 15 percent, while sulfur dioxide concentrations peaked in 1963, declining 40 percent between 1962 and 1969. Incidence of malaria had been reduced from 592 per million in 1940 to 1 in a million in 1960 with a significant assist from DDT. The death rate from various gastrointestinal diseases, which had been 1,427 per million in 1900 had declined to 6 in 1970 in large part due to chlorination. Similarly, and for the same reason, deaths from typhoid and paratyphoid which claimed 313 victims per million people in 1900 had been virtually eliminated by 1960. Cropland, nature’s major competitor for habitat that species need to survive, had peaked in the 1930s.

The heightened environmental consciousness signaled by the first Earth Day allowed Congress to pass grandly-titled laws and claim enormous credit for environmental battles that had, for the most part, already been fought and won in the shadows before these laws spotlighted them.

Why were things already improving, before the environmental quality laws were enacted? Mostly for economic reasons. As per capita wealth increased in the post World War II boom, families switched their home furnaces from coal over to oil or gas, creating an immediate air quality benefit. Trains, whose coal-fired steam engines had been among the leading causes of air pollution, also converted, first to diesel and then to electric. Power plants turned to more efficient facilities, and moved away from urban areas. While the federal government helped fund water treatment plants, it kept away from heavy-handed regulation. State and local regulation also helped to promote environmental quality, as individual communities began to attach a higher priority to the environment.

Today, America’s environment is cleaner—and Earth Day has indeed helped ensure that.

Earth Day allowed Congress to pass grandly-titled laws and claim enormous credit for environmental battles that had, for the most part, already been fought and wonBut our environmental impulses also have a dark side. The United States and other rich countries, having won their war over malaria with the help of DDT, now ban it within their borders. This ban, widely touted as one of the major environmental achievements of the 20th century, was aggressively exported through aid agencies and NGOs. It helped stall the worldwide campaign against malaria and contributed to the disease’s rebound in many developing countries.

Today, malaria kills more than a million people annually, mainly children in Africa. Fortunately, the pendulum on DDT seems to be swinging back with an assist from the US Agency for International Development, belated acceptance from the World Health Organization, and constant badgering from a few stalwart groups such as Africa Fighting Malaria., but with little thanks to politically-correct European bureaucracies and, at best, only grudging acceptance from NGOs previously in the vanguard for a global ban on DDT.

Environmental zealotry, this time over chlorine, also threatens to rollback the enormous public health related gains obtained from conquering death and disease from water-related diseases. It also threatens two of the more remarkable environmental achievements of the 20th century, namely, first, the near stabilization of humanity’s agricultural footprint, expansion of which is the single largest threat to biodiversity worldwide and, second, the spectacular reduction in chronic hunger and malnutrition.

Between 1990 and 2003, habitat lost globally to cropland increased less than 2 percent whereas population increased 20 percent, while the prevalence of chronic hunger in developing countries declined from 37 percent to 17 percent between 1970 and 2001 despite an 83 percent increase in population. These improvements are largely owed to wider adoption of more productive technologies which, among other things, produced more food per capita even as population increased.

However, there is unfinished business. Despite the improvements noted above, today about six million still perish each year from hunger and malnutrition. And population could grow another 50 percent by mid-century. Further improvements in agricultural productivity are jeopardized by the overwhelming and generally unfounded environmental antipathy to bioengineered crops, even though they promise to increase agricultural productivity while reducing dependence on pesticides and fertilizers. Considering the lives at stake, the results of this particular environmental campaign could be even more tragic than forsaking use of DDT for public health purposes.

On Earth Day, we should renew our promise to keep the environment clean—without adding to human misery or stalling improvements in the human condition.