Many people are concerned about the risks to the environment from economic growth. During the late 1700s and 1800s, the Industrial Revolution in the United Kingdom increased output and pollution as people moved to cities, and factories and homes burned coal. English cities such as Manchester and London had a dull haze that continually hung over them.  

Later pollution started falling as incomes increased, and people wanted cleaner environments. Firms responded to the demand for cleaner environments by switching from coal and developing new technologies to clean up the environment. Especially in the mid-20th century, government regulations led to more environmental improvements. 

In the United States, pollution emitted by manufacturers has steadily declined over the last several decades while output increased. Most of the pollution reduction was because of technological improvements rather than changes in imports or the types of goods produced. Between 1978 to 2001, manufacturing emissions of sulfur dioxide, nitrogen dioxide, carbon monoxide, and volatile organic compounds declined by 25% in the United States, while manufacturing output increased by 24%. Likewise, in the United States, pollution declined for other pollutants such as lead, DDT, and sewage. 

According to the World Health Organization (WHO), in developing countries, indoor air pollution is often very poor because of inefficient cooking, heating, and lighting, where they may use kerosene, wood, crop wastes, charcoal, coal, and dung. Worldwide, about 2.4 billion people cook using wood, crop waste, charcoal, coal, and dung. In urban areas, 14% of people relied on polluting fuels and technologies compared with 52% in rural areas. Poor indoor air quality especially harms women, children, and older people. WHO estimates that 3.2 million people die prematurely from indoor air pollution each year. As countries develop, indoor air quality improves as households use more efficient cooking, heating, and lighting methods. 

In 2016, WHO reported that 90% of worldwide pollution related deaths were in low- and middle-income countries. WHO adds that 94% of these air pollution-related deaths are from cardiovascular diseases, stroke, chronic obstructive pulmonary disease, and lung cancer. Major sources of human-caused air pollution include inefficient transport, household fuel and waste burning, inefficient coal plants, and industrial activities. Non-human sources of air pollution include dust storms, volcanic eruptions, forest fires, and methane from animals.  

Though there are environmental risks from war, pandemics, and pollution, much of the world has a cleaner environment than previously. We hope that the environment in the developing world also continues to improve.