A MAJOR study published last month in the Lancet, a British medical journal, found that there is a global killer responsible for more yearly deaths than AIDS, malaria and tuberculosis combined: pollution.

The problem is pervasive, affecting every country on the planet. It is expensive, costing the globe a whopping $4.6 trillion a year — about 6 percent of global gross domestic product — in hours not worked, premature deaths, health spending and eroded quality of life. The study associated pollution with 1 in 6 premature deaths, 9 million people in 2015. Even if the numbers are off a bit, the magnitude is striking.

Air pollution is the leading culprit, linked to 6.5 million deaths, followed by water pollution, with 1.8 million. Harmful particulates, toxic chemicals and smog-forming gases result from fuel burning, from primitive dung-fired cooking stoves to massive coal-burning power plants. These and other forms of pollution promote asthma, heart disease, stroke, lung cancer and other maladies. Premature death is only one problem. Long-term impairment before death also results in human misery and material impoverishment.

Developing nations, many of which lack strong environmental enforcement, are much worse off than developed countries, the study found. Poor and middle-income nations account for 92 percent of the premature deaths globally. Pollution drives a full quarter of deaths in some lower-income countries. The study's authors argue that this human toll is not the inevitable price of development, nor a problem that will simply disappear with growth; countries should not "wait for an economy to reach a magical tipping point that will solve the problems of environmental degradation and pollution-related disease," they write.

Instead, the authors insist, developing nations should look to the United States. The creation of the Environmental Protection Agency in 1970 and the enforcement of the Clean Air Act and the Clean Water Act, each passed in the early 1970s and updated since, resulted in dramatic reductions in harmful pollution, over a period of time in which the economy more than doubled in size. Not every pollution restriction that environmentalists dream up makes sense. But mandating relatively cheap pollution controls or, when possible, simply taxing polluters for the damage they do can result in a good value proposition for developing and developed nations alike.

Poor countries struggling to pull their citizens out of abject poverty may yet find it tough to take the long view. Many Americans, including those in the Trump administration, still fail to do so. Conservative critics of environmental rules often overstate the potential costs of pollution controls and discount the benefits. The Trump administration is on this basis weakening pollution rules across the board, sending an early signal about its approach by tapping Scott Pruitt, a climate-change denier, to lead the EPA. Yet the United States has hardly finished the job; the nation still sees tons of pollution pumped into the air, directly harming people and contributing to global warming. Meanwhile, the federal government has not yet addressed other forms of pollution, such as toxic chemical exposure, with needed rigor, and the Trump administration has sent negative signals about its intentions to do so.

The Lancet study should remind leaders in the United States and elsewhere that, though there are costs associated with restricting pollution, countries also incur costs by failing to do so. Finding the right balance requires acknowledging both sides and weighing them carefully.