The undated photo shows pedestrians on a Shanghai street on a sunny day. [Photo: Shanghai Morning Post]

Shanghai has been suffering from ozone pollution since July 24, and there is no sign of improvement, as reported by Shanghai Morning Post on Thursday.

Data from the Shanghai Environment Monitoring Center shows ozone pollution has been the primary pollutant in the city from July 24 to August 4. The most polluted day was August 4, when the air quality index (AQI) surged to 181. It is predicted that ozone pollution would continue this Thursday afternoon.

Chief forecaster from the Shanghai Environment Monitoring Center, Duan Yusen, explained that ozone pollution is a result of air pollution from automobile exhaust and industrial emissions; under high temperature and sunny conditions, such as the summer days in Shanghai, nitrogen oxide gases and volatile organic compounds react chemically to form ozone.

Ozone protects people from ultraviolet rays if it is up in the atmosphere. However, people's health is severely threatened by close exposure to ozone. Potential symptoms arising from prolonged exposure to ozone include respiratory diseases, coughing and damage to the immune system.

Breathing masks cannot prevent ozone pollution. Environmental departments advise people to avoid outdoor activities when the pollution is the most severe between 2 to 3 o'clock in the afternoon. Ozone pollution is naturally relieved in September.