When Yang Liyun was growing up in a small village in southwest China's Yunnan province, she didn't know that the eucalyptus trees growing everywhere on the surrounding mountains had any value other than as firewood.

So, when the 58-year-old opened her birthday gift from her daughter last month and saw a small bottle with the words "Essential eucalyptus oils" on the side, she could scarcely speak. In fact, her face clouded with doubt: the amber colored liquid looked very clean, which was a radical departure from her childhood memories.

Yang remembers how in the early 1980s people from other provinces occasionally visited her village. They built a fire on the side of the road, collected large amounts of eucalyptus leaves and boiled them in a big iron stewpot.

"They said they were extracting essential oils, but I didn't know what they were used for. However, the smell of the thick, dark gray liquid in the stewpot was unpleasant - almost pungent enough to wake a dead person," Yang said, wrinkling her nose as though the odor had jumped out from her memories and was permeating the room.

When she followed her daughter's advice and added several drops of essential eucalyptus oil to her ultrasonic humidifier, Yang's decades-long dislike of eucalyptus ended forever. For one thing, the fragrance gradually reduced discomfort in her upper respiratory tract that had lasted for several days.

"It's really amazing," she said.

According to Zhao Pingzhou, vice-president of Herbs-tale, a cosmetics brand that mainly focuses on natural essential oils, the oils have been used for years in Western countries to prevent disease or relieve discomfort.

Zhao said that diffusing certain oils, such as eucalyptus, can help people with respiratory conditions.

"The positive impact of essential oils is about more than just a soothing smell - the oils actually affect the central nervous system," he said. "Some oils can sharpen thinking (mint), calm emotions or reduce stress (camomile and rosemary) while others can help people sleep (lavender)."

Because some essential oils are highly antiviral and antibacterial, they can safely be used to disinfect the living environment without posing a risk to health. Zhao said many homemakers, especially those with babies or pets, choose lemongrass oil to drive away mosquitoes and tea tree oil to clean floors and clothing.

"Although the role of essential oils in the field of preventive medicine still sounds new to many Chinese, it will definitely become more popular and better known in the near future," he said.

(China Daily 03/23/2016 page6)