The smog that blanketed more than 100 cities across half of China last week has rekindled criticism of China's dire record in combating pollution.

The serious endemic air pollution problem has become a top complaint among urban residents, concerned about the deadly health risks.

The Air Quality Index neared or topped 500 in dozens of eastern China cities last week. The index of more than 300 cities was defined as "serious" by China's official air monitoring authorities.

People rushed to buy face masks and air purifiers as Nanjing primary and middle schools closed for two days.

"Smog is everywhere," said Xiong Yuehui, head of the science and technology department of the Ministry of Environmental Protection, at a meeting on Sunday.

The world's second-largest economy does not lack money or technology to clean the air, Xiong said, but lacks "implementation of concrete efforts."

About 22 million tons of sulfur dioxide are belched untreated into China's air each year, according to ministry data. Another 40 million tons of emissions have the sulfur removed.

Luo Jianhua, secretary-general of the China Environment Service Industry Association of the All-China Federation of Industry & Commerce, doubts  the official statistic.

Many polluting companies shut down their treatment facilities to cut costs, he noted.

Bian Cheng, chairman of environmental protection equipment manufacturer Keda Industrial Company, blamed loose supervision and called for tougher law enforcement.

Wu Xiaoqing, vice-minister of environmental protection, said the agency was working to put in place a system that punished government officials for environmental lapses.

The ministry is also reportedly working on toughening proposed environmental protection standards.

"The new standards approved last week called for some 2,000 cement plants nationwide to improve pollution treatment facilities," Wu said.

Xiong said cities nationwide will enforce fine-particle emission limits in mid-2014, forcing high-polluting plants to upgrade their treatment facilities.

Coal is the main cause of smog, Bian Cheng said, and China can only go so far in minimizing coal consumption.

"If coal can be used in a cleaner way, air quality would then see a dramatic improvement," Bian said.

Meanwhile, a computer model, capable of more accurately forecasting and analyzing the cause of smoggy days is expected to go into operation in the following three to five years, said Meng Xiangfei, a researcher at the National Supercomputer Center.