The term 'Dangerous Beijing Blanket' refers to the SMOG that has been a major problem in Beijing, China for many years. SMOG is a combination of smoke and fog that is created by the burning of fossil fuels and other pollutants. It can cause serious health problems, including respiratory illnesses, heart disease, and cancer. The SMOG in Beijing has been so bad that it has been referred to as a 'Dangerous Beijing Blanket.'