Residents in Wuhan, Hubei Province protect themselves against sudden serious air pollution with masks while walking outside. Several cities in Hubei were shrouded in heavy smog Monday, sparking public outrage. An initial investigation found it was caused by the burning of straw in neighboring provinces. Photo: CFP

Severe air pollution in several provinces has triggered public outrage and prompted local governments to take action against the traditional burning of straw that has been pinpointed as the "arch-culprit."

Several cities in Hubei Province, including its capital Wuhan, were hit by heavy smoggy weather Monday.

Figures from the Wuhan Environmental Monitoring Center showed that the PM concentrations quickly rose from 7 am and reached 0.574 micrograms per cubic meter at 2 pm, compared to the standard of 0.150.

The Hubei Provincial Environmental Protection Department released its initial investigation results Monday afternoon, saying the possibility of industrial pollution being the cause had been eliminated, with the most likely culprit being the burning of straw in neighboring provinces.

The sudden invasion of haze was similar to one in Jiangsu Province over the weekend when residents of several cities felt suffocated while smelling something burning.

The Nanjing Environmental Protection Bureau (NEPB) announced on its official microblog on Saturday night that the instant value of the air pollution index jumped to 478, making it the most polluted city among the 120 cities publishing the same index.

The PM2.5 readings in 13 cities all greatly exceeded the standard as of Sunday night, according to the Yantze Evening News.

The rarely seen pollution even swept into some cities in Shandong and Henan provinces. The provincial observatory of Jiangsu issued a yellow warning signal for haze on Sunday, as did Wuhan Monday.

The NEPB on Sunday pointed to the burning of straw in Jiangsu and Anhui as the primary cause for the pollution, which was exacerbated by unfavorable meteorological factors.

The Nanjing city government later pledged to strengthen investigations into the straw burning, which was made illegal in 2009, and work to find an alternative to the outdated tradition.

Jiangsu produces more than 40 million tons of straw annually, ranking fourth nationwide, according to the bureau.

Zhang Jianyong, a deputy director of the Jiangsu Province Agricultural Commission, said straw was used by residents all year round as the main domestic fuel in the past, whereas now with the availability of different energy sources, it is collected and burnt after crops are harvested.

Zhang Yuanxun, a professor of resources and environment at the Chinese Academy of Social Sciences, told the Global Times Monday that the most direct way for farmers to get rid of waste straw is burning, as it does not cost any money or require any technical skills. In addition, the ash can be used as natural fertilizer.

He suggested that the government increase subsidies for farmers to encourage them not to burn waste straw.

"It is no exaggeration to say that the negative impact of these air pollutants on human health is similar to smoking several packs of cigarettes when people are exposed to it," he said.

Zhang Jianyong said addressing the problem cannot rely merely on administrative measures, suggesting that other options include comprehensive utilization by returning the straw to fields mechanically or having them industrialized.