Studies have shown that components of air pollution increase the risk of obesity, heart disease and type 2 diabetes. The tiny particles present in traffic fumes and cigarette smoke have the ability to trigger widespread inflammation in the body, which disrupts metabolism and promotes weight gain. Most people only associate air pollution with lung problems, but we’re now learning the harmful effects can be felt right throughout the body. A team of researchers undertook a study on laboratory mice. Some were given clean filtered air to breathe, while others breathed the type of air found at a busy road in a large city. The scientists weighed the mice and conducted a number of tests to assess the health of their metabolism. After only 10 weeks the results were startling. The mice exposed to polluted air showed higher volumes of body fat, both around their belly and internal organs. Interestingly, their fat cells were actually 20 percent larger. The affected mice seemed to have become less sensitive to insulin. So after only 10 weeks they developed insulin resistance (syndrome X), which is a forerunner to type 2 diabetes. This can be quite depressing news, depending on where you live. One thing you can do is not smoke cigarettes. If you are lucky enough to have a yard, planting a garden will help because the plants remove a lot of pollutants from the air. Keeping some indoor plants will also help to keep your air cleaner. Body weight and metabolism are affected by a large range of factors. It is not simply a matter of how much you eat and exercise.     Reference