Author: Tara Alderson

Date: 12/8/10


Hong Kong's waterfront, obscured by photochemical smog (31/8/09) - Alex Hofford (

Smog is a combination of the words smoke and fog and can be categorized into two different types: photochemical (summer) smog and acid (winter) smog. [1]

Photochemical smog mainly consists of ozone and is brownish in colour; nitrogen oxides and VOC’s, which originate from traffic and industries, causes this type of smog. [1]

Acid, or winter smog, is found in areas where vertical dispersion of air pollutants is not possible. [1]


West Kowloon, obscured by photochemical smog (13/9/09) - Alex Hofford (


  1. 1.0 1.1 1.2 FAQ air pollution, (2009). Lenntech BV - last accessed 7/8/10