In the mid-20th century, industrial and economic progress in Europe and the U.S. greatly improved standards of living and population health, but also resulted in substantial increases in air pollution, with significant effects on public health. Intense pollution episodes in Belgium in the 1930s, Donora, Pa., in the 1940s, and the London Fog of December 1952 brought these new problems to much wider public attention.
The result was the first Clean Air Act regulations in England and the U.S. in the 1950s, passage and implementation of more comprehensive legislation beginning in the 1970s, and substantial reductions in exposures to nearly all pollutants over the past 40-plus years. This progress was widely recognized in the U.S. and Europe, and analyses of the U.S. Clean Air Act benefits and costs documented the much higher benefits than costs of these improvements.
Starting in the 1990s, however, new population studies of exposure to fine particle air pollution (PM2.5) reported continuing effects on mortality and hospitalization, even at the now reduced levels of exposure, resulting in further— and continuing—efforts to reduce exposure even in the developed economies of the world.
New and Rapidly Growing Challenge
At the same time, a new Industrial Revolution was taking shape in the rapidly emerging economies of Asia and elsewhere around the globe. Not unlike the first revolution, this economic progress has improved living standards and health and extended life substantially in every country in the world. While a benefit worldwide, those improvements also have been accompanied by a new set of challenges: Air pollution levels have risen substantially, populations are growing, and people living to older ages are going through an “epidemiological transition,” no longer dying from the “diseases of poverty” (e.g. poor sanitation and waterborne disease) but from heart and lung disease—both of which have been most closely tied to the health effects of air pollution.
The rapid increase in these economies, much like their predecessors in the US and Europe in the mid-20th century, has resulted in a dramatic increase in air pollution exposure from factories, electric generating stations, and vehicles, as well as more traditional sources such as household burning of dung, wood, and poor-quality coal. The result, is that the best estimates of PM2.5 exposure today find that more than 90 percent of the world’s population is living in areas that exceed—in some cases substantially—the Air Quality Guideline for PM2.5 set by the World Health Organization.
Today, a growing body of scientific evidence with more than 40 large population studies of air pollution and health in 16 countries reporting PM2.5 effects is documenting the continuing and growing challenge of addressing air pollution as a significant risk factor for population health. Each year, the Institute for Health Metrics and Evaluation (IHME) at the University of Washington—and its collaborators on air pollution led by scientists from the Health Effects Institute—publish the Global Burden of Disease, designed to systematically test a range of health risk factors (e.g. smoking, obesity, traffic accidents, and air pollution among many). Those analyses are now reporting that ambient PM2.5 pollution contributed to more than 4 million premature deaths in 2016, with air pollution among the top risk factors worldwide.
First Steps Toward Solutions
This burden is especially acute in the two most populous countries on earth— China and India, which account for more than half of the impact—but also affects large areas of South and Southeast Asia, Eastern Europe, and sub-Saharan Africa. In recent years, however, these countries, especially China, have become increasingly aware of the seriousness of the problem following very high exposure episodes in the winters of the past decade, and have begun to act.
As was the case in the U.S. and Europe in the 20th century, these efforts have started by attempting to identify the sources of the pollution in each country. This analysis—source apportionment—is a critical first step toward action. Often the most readily observed sources of air pollution, e.g. motor vehicles in the cities, are important contributors but not the major contributors to what each city resident is breathing, which can include emissions from more distant factories and electric power plants, as well as significant contributions to outdoor air pollution from the indoor burning of wood, dung, and poor-quality coal. Two recent analyses of these sources and their health burdens in China and India by HEI’s Global Burden of Disease from Major Air Pollution Sources (GBD MAPS) have demonstrated the complex set of sources that must be addressed to see progress on air pollution.
Fortunately, a number of the technologies that are needed to address these diverse sources already exist—and can and are being transferred to developing countries. China and India, for example, have already set their timetable to require all new vehicles sold in their countries starting in 2020 to meet the EURO VI/6 standards for such vehicles, applying the latest pollution control technologies. China has taken a sweeping set of actions far beyond that, requiring each province and city to conduct source apportionment analyses, greatly expanding their air quality monitoring (and making it more transparent), requiring power plants and industry to install the latest pollution control technologies, and holding local and provincial officials accountable if they do not meet air quality targets.
Although China still has quite a bit further to go to reduce its air pollution to safe levels, there is evidence now coming forward that China is making real and measurable progress in reducing emissions and exposure.
It is heartening to see the progress to date—and India is beginning as well to take the first steps for reducing pollution. There are, however, continuing and growing challenges.
First, it has become apparent that merely adopting tighter emissions standards does not guarantee improvements (as recent experience with Volkswagen and other diesel car manufacturers has shown). This will require the establishment of government oversight laws and structures sufficient to ensure continuing compliance with any rules that are adopted. In some cases this will require an even more basic step—the adoption of foundational laws, such as the U.S. Clean Air Act, which do not currently exist in countries like India.
Second, there is growing evidence, even as PM2.5 levels are going down, that the levels of ground-level ozone are increasingly posing a new and more complicated challenge to understanding the complex sources that contribute to ozone formation, and can vary by location and meteorological conditions. Even the U.S. is still grappling with residual ozone challenges after many years of reducing volatile organic compounds (VOCs) and nitrogen oxide emissions. Climate change is further expected to increase ozone as summer temperatures rise.
Finally, it is clear from experience in the U.S. and Europe that as pollution levels come down, the efforts to achieve further reduction become more and more challenging, industries raise increasing concerns about the cost of compliance, and controversy increases. This has not meant that progress has stopped but has required a higher level of scientific and technical analysis, subject to increasingly intense scrutiny, to justify any further actions.
Conclusion: Progress as Challenge Grows
During the past 150 years, economies around the world have developed in accord with the Kuznets Principle (first identified by Polish Economics Nobel Laureates Josef Kuznets). As economies grow rapidly into industrial powers, incomes and standards of living improve, but pollution increases rapidly as well.
Once economies achieve a certain level of progress, however, pollution begins to be addressed and begins to fall, likely for several reasons, including enhanced incomes and leisure time leading to growing public and political interest in pollution reduction, economic pressure to improve the efficiency of industry (and thus reduce waste and pollution), and growing government resources and knowledge to address the pollution issues. The result, in economies in North America, Western Europe, and East Asia (Korea and Japan) has been reducing air pollution in the 20th and early 21st centuries.
Now, these same trends are playing out in many other countries, with rapid economic growth and dramatic increases in pollution. Countries such as China, which is in the vanguard among these rapidly developing economies, are in fact beginning to act, in part due to the desire of developing a more modern and efficient industrial base, and in part in response to the growing number of Chinese people expressing concern about air pollution effects on their families. Even lower-level economies in Asia and sub-Saharan Africa are seeing a steady reduction in exposure to and health effects from household air pollution—a significant source of burden in these regions—as improving economies make cleaner household energy sources (e.g. natural gas, electricity) increasingly available and affordable.
But it is important to remember that today’s developed economies have been working on cleaner air for many decades (the U.S. for nearly 50 years), and there are still challenges even at lower pollution levels. While China has made tremendous strides, its air quality still far exceeds the WHO Air Quality Guidelines, and now further development is raising new pollutants of concern. At the same time, the aging populations in China and throughout Asia, Africa, and Eastern Europe mean that even as pollution begins to fall, the number of people facing pollution-sensitive heart and lung disease is rising.
Despite the challenges, however, there is reason for optimism, with past documented success in reducing pollution in the U.S. and Western Europe, technologies already available to accomplish that progress, as well as substantial business opportunities for the purveyors of the many innovative technology solutions. Though it will not happen overnight, we can expect that with government and private sector commitment, and improving economic resources, we will continue to see improving air quality and enhanced public health.
Dan Greenbaum is president and chief executive officer of the Health Effects Institute. He leads HEI’s efforts, supported jointly by government and industry to provide public and private decision makers—in the U.S., Europe, Asia, and Latin America—with high quality, impartial, relevant, and credible science about the health effects of air pollution to inform air quality decisions in the developed and developing world.
The opinions expressed here do not represent those of Bloomberg Environment, which welcomes other points of view.