air pollution in HK

1. Its affecting the air quality in Hong Kong
2. The Visibility in Hong Kong is less than eight kilometers for 30% of the year
3. Cases of asthma and bronchial infections have soared in recent years due to reduced air quality
4. Health issues had increased due to the increase of air pollution in Hong Kong
5. Cars ( Co2 )
6. People Smoking / cigarette ( The air pollution emitted by cigarettes is 10 times greater than diesel car exhaust, suggests a controlled experiment, reported in Tobacco Control. )

香港吹北風時，污染特別嚴重，想知點解，自己STUDY。