London’s Great Smog of 1952 resulted in thousands of premature deaths and even more people becoming ill. The five December days the smog lasted may have also resulted in thousands more cases of childhood and adult asthma. Researchers studied how London’s Great Smog affected early childhood health and the long-term health consequences. The results showed that the Great Smog event of 1952 likely still affects some people’s health more than 60 years later.