"When I first arrived here, it felt like carrying a 30-kilogram load on my back when walking. Even a short distance would leave me breathless. Due to the lack of oxygen, headaches were common, making it difficult to sleep at night," said deputy director of the Waliguan observatory Wang Jianqiong, who's been working at the station for over 20 years.

Wang's colleague, Hu Chengrong, appears on the rooftop of the observatory each day before 8 am to survey the surroundings. He records the cloud cover, visibility and weather phenomena in a logbook. These manual observations are conducted three times a day — morning, noon and evening.

"It's a bit easier now. The older workers at the station said that in the past, all meteorological observation data was recorded manually every 3 hours, 24 hours a day, year-round without breaks," Hu said. "Back then, on really windy days, two people had to tie themselves together to avoid being blown away when walking outside."

To ensure the absolute purity of the atmosphere sample being taken, observers must hold their breath before cleaning and sterilizing the sample container and running it downwind some 10 meters. From there, the container is left to collect its atmosphere sample for the next 15 minutes.

"The procedures for bottle cleaning and sampling are strictly regulated to prevent exhaled gases of the staff from affecting the results," said observer Wang Ningzhang. To avoid the influence of near-surface updrafts on air samples, sampling must be completed before 9 am each day.

To protect the air on the mountain from human interference to the greatest extent possible, the observatory is staffed with two workers in each team, who rotate shifts every seven days. While on the mountain, the workers cannot make fires for cooking and instead eat dry rations and instant noodles.

Those wishing to visit Mount Waliguan may encounter Tibetan volunteers at the foot of the mountain discouraging them from ascending to avoid affecting the monitoring results.