Last month, the Civil Aviation Administration of China, the mainland's aviation regulator, dramatically expanded its five-year plan to increase airport capacity. It now wants to build 82 airports, up from a goal of 56 set in 2010. And it wants to expand 101 airports, up from the previous 91. Maybe Guangzhou is hoping to get in on the action.

But talk of a second airport came as a shock to many observers in and beyond Guangzhou. The city ended last year more than 88 billion yuan (HK$108 billion) in debt from hosting the Asian Games two years ago, a sum that some government critics contend could actually be closer to 210 billion yuan.

Moreover, the region already has what some argue is an overabundance of airport capacity. In addition to Baiyun, where a third runway is being built, surrounding Guangdong province already has airports in Foshan , Huizhou , Shenzhen and Zhuhai . A sixth, Jieyang Chaoshan International Airport, is expected to open soon in the province's eastern reaches.

That's not counting the two major international airports in Hong Kong and Macau. The proposed airport in Guangzhou's Nansha district would be just 60 kilometres from the airport at Chek Lap Kok, where authorities have also been talking about a third runway.

All of this has caused academics, commentators and members of the public to question whether the planned airport is another unnecessary infrastructure project to boost the city's gross domestic product with taxpayers' money.

Wang Han, a researcher with the Guangzhou-based Urban Research Institute of South China, told The Southern Metropolis News that the government should first consider consolidating existing airport resources.

More than 60 per cent of Yangcheng Evening News readers voted against the idea in an online poll this week, with many saying it was too early to think about building a second airport.

Several noted that Baiyun airport would be able to handle an estimated 75 million travellers per year once the runway project was completed, up from 45 million travellers last year.

Others pointed out that the airports in Foshan and Zhuhai are already underused.

The Zhuhai airport was one of the largest airports of its kind at the time of its construction in 1995 and was designed to handle as many 12 million domestic travellers a year. Today, it still doesn't serve a single international flight, it handles fewer than two million passengers each year, and some of its facilities sit unused.

Similarly, Shati airport, a former military airfield in Foshan which opened to the public in 2009, only has one daily flight to Beijing. Competition may be one of its problems, because it is only 25 kilometres from downtown Guangzhou.

There's a question about whether a seventh airport would make the Pearl River Delta's airspace overcrowded. Shenzhen Baoan International Airport is only 99 kilometres from Baiyun airport and would be less than 50 kilometres from the proposed Nansha facility.

Additionally, the Nansha area includes environmentally sensitive wetlands that provide habitats for many species of migratory birds. Some prominent Guangzhou voices, such as commentator Chen Yang, have already begun to raise concerns about potential environmental impact.

'If an international airport is really being built in Nansha, there is no need to talk about wetlands, as even the quality of human habitats on dry land will be ruined,' Chen wrote in his regular column.

There's increased competition from rail, too. Guangzhou's high- speed-railway transport hub in Shibi, Panyu, is less than 60 kilometres from Nansha. Using the high-speed network, passengers from Guangzhou can reach Wuhan , Hubei province, in three hours; Changsha , in Hunan province, in an hour and half; and Shaoguan in northern Guangdong in less than 45 minutes. Not to mention that Guangdong also has one of the best highway networks on the mainland.

Peng Peng, a researcher at the Guangzhou Academy of Social Sciences, noted that cities normally talk about a second airport only after the first airport's annual passenger load hits 90 million. He said Beijing followed that model but officials in Atlanta - one of the United States' busiest hubs - decided against a second airport even after hitting the 90-million mark.

Peng said the government should first make better use of other airports in the delta.

All said, it seems obvious that Guangzhou is trying to boost GDP while securing its status as the third-largest city in China by catching up on the construction frenzy.