The Shanghai government has agreed to pay for special air quality monitoring equipment after Ministry of Environmental Protection officials said cost was the biggest obstacle to the adoption of a stricter standard across China.

PM2.5 refers to particles with a diameter of 2.5 micrometers or less. They can pose major health risks as they are small enough to lodge deep in the lungs and even enter the bloodstream. [Shanghai Youth Daily]

This year, Shanghai, Beijing, Tianjin and Yangtze River Delta and Zhujiang River Delta regions and provincial capitals will be the first to adopt PM2.5 and ozone monitoring, which will spread to 113 key cities next year, all major cities in 2015 and nationwide in 2016.

PM2.5 refers to particles with a diameter of 2.5 micrometers or less. They can pose major health risks as they are small enough to lodge deep in the lungs and even enter the bloodstream. Currently, Chinese cities adopt the less sensitive PM10 standard in reporting air quality.

Zhu Jianping, of the ministry's environmental monitoring department, said the cost of the monitoring equipment was the main reason for the new system being introduced in four steps.

He said one set of PM2.5 equipment cost at least 80,000 yuan (US$12,710), while the most expensive could cost 380,000 yuan. Provinces haven't included the cost in their 2012 budget as PM2.5 and ozone monitoring was only recently mentioned by the ministry.

Zhu said the country's investment on such equipment could total more than 2 billion yuan.

Fu Qingyan, chief engineer of the Shanghai Environmental Monitoring Center, said the city hasn't included the equipment in this year's budget but the city government has already agreed on the extra expenditure.

She said the ministry was working on a unified PM2.5 monitoring method and Shanghai would buy equipment after a decision was reached.

"Several cities including Shanghai have started trials of PM2.5 monitoring, however each's monitoring and measuring method may be different," she said. "We have all reported the methods to the ministry, which may work out a unified monitoring system in about six months."

Shanghai has failed to meet the proposed PM2.5 air quality standard for the past five years with the center's data showing that the average density of PM2.5 was higher than the proposed PM2.5 standard every year since a pilot study began in 2005.

The watchdog's data was collected from 24 monitoring sites across the city.