Compared to smoking, the polluted air in some places is so bad that inhaling it can be worse than smoking a pack of cigarettes. According to the University of California, smoking 1 cigarette a day is roughly the equivalent of 22 ug/m3. Beijing for example, had an average PM2.5 level of 85 ug/m3 in 2017: 4 cigarettes per day. You can download the app: ‘I smoke!’ to see how many cigarettes the pollution is equivalent to where you are. Read more about it here