A man wearing a mask walks on a street on a hazy day in Beijing in this file photo taken on October 24, 2014. REUTERS/Kim Kyung-Hoon

BEIJING (Reuters) - China needs to slash emission levels by as much as half before any obvious improvements are made to its environment, a senior government official said on Friday, underscoring the challenges facing the country after three decades of breakneck growth.

Zhai Qing, China’s deputy minister of environmental protection, told a briefing that pollutants had been cut by just “a few percentage points” since 2006 and had to drop much further if any progress is to be made.

“According to expert assessments, emissions will have to fall another 30-50 percent below current levels if we are to see noticeable changes in environmental quality,” he said.

China has vowed to close vast swathes of ageing heavy industrial capacity and slash coal consumption in heavily populated eastern coastal regions as part of its war on pollution.

Last November, it imposed draconian restrictions on industry throughout northern China in order to guarantee air quality during the Asia-Pacific Economic Cooperation (APEC) summit held in Beijing. Zhai said emissions in the region fell by more than 50 percent during the meeting.

He said China’s ability to control pollution was still “limited” and its policies still needed to be improved.

Only eight of the 74 cities monitored by the ministry met national pollution standards last year, according to official data published earlier this month.