What is interesting is the political battle between the centre and the regions. When central government uses local officials to monitor pollution levels of firms that the local officials have a financial stake in it is clear that this conflict of interest will lead to tension.
China and environmental accidents
Environmental Regulations in China: The battle between Beijing and the regions
A quote from one of the articles (original source PlanetArk):
Many Chinese factories, smelters and power plants have bought equipment to minimise pollution from smokestacks, but are notorious for turning off the equipment as soon as government inspectors leave their gates.
Scrubbers and other equipment can be expensive to operate, or can reduce the energy efficiency of a plant, tempting owners to flout the rules.
Understaffed environmental bureaux lack the manpower or the clout to enforce compliance, since they often report to local governments that own stakes in local industry.