Most big cities in the world have air pollution levels which are beyond safe limits prescribed by WHO.
We as citizen elect government to protect our wellbeing. Most politicians are too afraid to take harsh actions to control air pollution, because the measurers involved can make them unpopular or big corporations who get affected have strong lobby not let these measures get implemented. While we have rules to punish someone who physically harms us but there is no recourse to hold government accountable for air pollution, which is a slow poison. For example, breathing air in Delhi is equal to smoking 10 cigarettes per day, now image your children have to go through this as well.
As law makes it mandatory to put health warning on cigarettes, similarly whenever a person travels to these cities they should be a mechanism to warn them about the air pollution hazard.