Shanghai has set a target for clean air, aiming to bring down the average density of tiny particle PM2.5 to 37 micrograms per cubic meter by 2020 and below 35 by 2022.

The city government has approved the five-year (2018-2022) draft plan for cleaner air. The plan states the Air Quality Index shall not be higher than 100 for at least 80 percent of the year. Heavily polluted days — with AQI higher than 200 — is expected to be a thing of the past by 2020.

Environmental experts have long said PM2.5 and ozone are Shanghai’s major pollutants. Ozone pollution is created by the daylight ultra violet rays and occurs more often in summer.

Pollutants from volatile organic compounds (VOCs) and nitrogen oxide can also cause excess amount of ozone.

“Our fight is not only against PM2.5 and ozone, but other air pollutants as well. It will only get difficult and tougher,” said Zhou Jun, deputy director of Shanghai Environmental Protection Bureau’s pollution control division. Zhou said there is a need for both financial and manpower support.

Earlier reports had suggested that Shanghai would invest about 440 billion yuan (US$66 billion) for environmental protection work from 2016 to 2020, up 37.5 percent from the last five years.

“The easier part of our work has been done over the past few years such as removing polluting boilers and eliminating heavily polluting vehicles. Now comes the more detailed work, and it will require much more efforts to create visible improvement,” Zhou added.

According to 2017 Shanghai Environmental Bulletin, the average density of PM2.5 particles dropped 13.3 percent to 39 micrograms per cubic meter last year, from 45 in 2016. Last year, 75.3 percent days had excellent or good air quality, with AQI not higher than 100.

The average density of other air pollutants such as PM10 and sulfur dioxide also fell in 2017. But the average density of nitrogen dioxide went up. Ozone pollution also rose last year.

The five-year clean air plan has spelled out 131 detailed measures, among them stricter control against polluting sources. Adjustments will also be made in the industrial, transport and energy structures.

By 2020, Shanghai’s consumption of coal will be 5 percent less than in 2015. Low-nitrogen combustion technology will be used for oil and gas boilers.

Industries such as petrochemical, automaking, furniture making, shipbuilding, printing, packaging and electronic parts manufacturing will be watched for VOC emissions. Low-volatility solvent products will also be promoted in relevant industries.

Green-energy vehicles will become almost mandatory for taxi companies, governments, sanitation and postal service providers as well as logistic and delivery companies.

There will be about 450 kilometers of bus-only lanes by 2020. Ships will be required to use low-sulphur fuel.

Zhou said Shanghai’s air quality in the first half of the year was slightly worse than the same period of last year. “Air quality is affected by many factors, and the index tends to go up and down instead of decreasing steadily. We can’t promise specific goals for each year, but improvements will be made in the long term,” said Zhou.