A new report issued this week by the environmental research group C3 Solutions provides data to show that countries with more economic freedom and higher GDP have cleaner environments. As income increases, people demand cleaner air and water, and move to places that have a healthier environment.

Entitled Free Economies Are Clean Economics, the report correlates the Index of Economic Freedom, published by the Heritage Foundation (where I work), with the Yale University Environmental Performance Index, showing the cleanliness of the environment, as well as other measures of economic performance.

According to the report, countries such as Burundi, Equatorial New Guinea, and the Democratic Republic of the Congo have low levels of freedom and low environmental standards. Spain, Poland, and Thailand are in the middle tier. Canada and the United Kingdom are described as “Middle High.” Some of the cleanest and richest are Singapore, Australia, Switzerland, and Ireland.

Countries that generate income through the service economy, such as Switzerland with its banking sector, are more likely to be well-off and clean than a country that generates income through energy-intensive manufacturing.