From Asia to Europe to North America, poor air quality is making people sick and, in some cases, killing them at an early age. Air pollution causes six million premature deaths every year worldwide. This number comes from studies done by the World Health Organization (WHO). Thirty-three of Europe's most polluted cities are in Poland. Part of the reason is how Poles heat their homes. In the winter, many people keep warm by burning coal. Northern China has a similar problem. And it is a big problem. Burning coal releases dirty particulate matter into the atmosphere. Particulate matter, sometimes called PM for short, is a mixture of solid particles and liquid droplets found in the air. Some particles, such as dust, dirt, soot, or smoke, are so large or dark that we can see them with the naked eye. Others are so small that we can only see them using an electron microscope. Scientists say particulates, in large amounts, are partly responsible for changes in Earth’s climate and serious health problems.
