Majority of people smoke in Cairo, beside cigarettes, the hookah is quite common too in cafes. Theoretically , there is legislation that prohibits smoking  in public places but it is pretty lenient. you could easily find someone smoking just steps away from the very vivid “no smoking ” sign. Most of the indoor areas are crowded and smoky, there is no outdoor area with designated smoking area for smokers. The quality of the air is pretty bad with this smoke and no one can really enforce the “no smoking” rule. You can this issue obviously in public transportation and street markets. Airports is little better , the rules of no smoking is strict specially in Cairo international airport, there are designated smoking areas. The rule gets softer if you are in a domestic flight in a smaller airport like Hurghada or Sharm el Sheikh. Most of my relatives has asmtha problems , I would guess from the habit of indoor smoking , most houses are smoky. At least one person in household smokes. I suggested to get an air purifier but those are not common in Cairo.