TIANJIN -- Tianjin began charging factories for emissions of volatile organic compounds (VOC), a major contributor to air pollution, on Sunday.

The charge applies to petrochemical, packaging and printing companies in the northern Chinese city.

The standard charge is set at 10 yuan ($1.5) per kg, but authorities will grant a 50-percent discount to companies discharging less than half of the national limit while tripling the charge for those that exceed the limit in both volume and density of VOC discharge.

This is the latest fine imposed by Chinese cities on polluting companies. Beijing has increased its charges for pollutants ranging from sulfur dioxide, nitrogen oxides to ammonia nitrogen to 14-15 times the level they were at in 2014, in the hope of making it too costly for factories to pollute the environment.

Such efforts have paid off. Emissions of sulfur dioxide and nitrogen oxides have dropped 48.3 and 47.9 percent in Tianjin in a year, said Jia Chunning, an official with Tianjin's environmental watchdog.