In the sweltering heat of summer, when the refreshing breezes desert the city, Hu Lianqun absent-mindedly reaches for a solution: He rolls up his shirt to expose his belly, often fanning himself with the garment to create his own air conditioning.

From the countryside to sophisticated urban centers such as Beijing, men of all ages, social standing and stomach sizes resort to a public display of skin, a hot-weather fashion faux pas that’s the Chinese equivalent of knee-high black socks with shorts.

They’re known as bang ye, or “exposing grandfathers"(despite their age range). In the hottest weather, bang ye seem to be everywhere, striding among the tall buildings in Beijing’s business district, playing chess in parks, holding children’s hands at the zoo and negotiating crowded alleyways.

There are precious few washboard abs among the lot. Still, many fail to notice that they’re drawing smirks from fashion-conscious passersby. Most just don’t care.

“I don’t know, it just feels cooler,” says Hu, perched on a park bench on a sultry weekday morning, the temperatures already into the 90s, the humidity soaring. “Look, you just shake your shirt to create a breeze. I don’t see anyone laughing at me.”

In the sports attire section of a nearby department store, Qi Tong scoffs at such reasoning.

“It lowers Beijing’s standing as an international city,” the 21-year-old says. “I go without a shirt sometimes at home, but never in public. If my dad reaches for his shirt when I’m out with him, I threaten to go home. It’s just too embarrassing.”

Says a shopper in the men’s suits section: “I’d never do it. It’s uncivilized.”

In recent years, China has shown a keen awareness of its public image. Before the 2008 Summer Olympics, Beijing’s Spiritual Civilization Steering Committee railed against such bad manners as spitting, cursing, cutting in line, urinating in public, sleeping on park benches and loudly slurping food.

During this summer’s World Expo, the mayor of Shanghai has urged residents to stop running red lights and strolling the streets in pajamas, a popular summer attire.

But male belly-baring has proved a tough habit to beat. Years ago, men often did the full Monty with their shirts, taking them off completely, as a way to beat the heat, prompting fashionistas to put their foot down.

In 2002, one Beijing newspaper even sponsored a campaign to drive home the point that going shirtless was gauche. Each day, the Beijing Youth Daily ran candid pictures of shirtless men, often with bellies bulging, in an effort to shame offenders into compliance.

But as on the catwalks of Paris, style evolves. In Beijing, it soon morphed into the rolled-up-shirt look. Some go even further to beat the heat, rolling up their pants legs.

Many defend the practice, insisting that history is also on their side: During the Cultural Revolution, when good manners were condemned as bourgeois, it was considered a compliment to be called a dalaocu, or “a rough old guy.”

Chinese men haven’t looked to their leaders for guidance on proper etiquette. Mao Tse-tung often scratched himself in public, and Deng Xiaoping, a notorious spitter, often kept a spittoon nearby when meeting with world leaders.

Although many men proclaim the health benefits of exposing their stomachs on hot days, one Eastern medicine practitioner says he doesn’t want to be blamed for the practice.

“Exposing one’s belly has nothing to do with Chinese medicine’s theory about maintaining a person’s health,” says Yan Zheng, who has been practicing Chinese medicine for more than 40 years.

“People chose to expose their belly because they feel too hot in summer but feel embarrassed to take off their shirts completely.”

Cai Keqing says he doesn’t worry about embarrassment. Taking a break from his retail sales job, the 24-year-old slouches on a park bench, shirt hiked up, and smokes a cigarette.

He’s heard all the arguments about skin-exposing men. “Right now, I couldn’t care less about my public image,” he says. “It’s just too hot.”

john.glionna@latimes.com

Tommy Yang in The Times’ Beijing Bureau contributed to this report.