About 300 cans of fresh air from south China's Hainan Province, a seaside tourism resort, were sold at the ongoing 2016 Hainan International Tourism Trade Expo.

Selling at a discount price of 29 yuan (about 4.5 US dollars), the cans of air have sparked a buying spree by enterprises and tourists from smoggy cities in the north and northeast China.

It was bottled in Bawangling, Changjiang County of southwest Hainan, where the forest coverage is up to 98 percent.

Bawangling's average negative oxygen ions per cubic centimeter reach as high as 6,000, six times the standard of clean air stated by the World Health Organization.

"The first batch of 300 cans were all sold out, and it will start selling to the public in two months," said Liu Jin, deputy county chief of Changjiang at the expo, who introduced the product.

Companies are already in negotiation to further research and development for larger sizes and different applications, said Liu.