Such Great Heights

Upon graduating college last year, I was awarded a traveling fellowship that offered me the once-in-a-lifetime opportunity to put my life on hold for a year, ship off to Asia, and explore that five-thousand-year-old nation called China while writing a novel. Beyond some initial difficulties — learning to cope with everyday crowds reminiscent of Black Friday shoppers at a Walmart and getting over my initial hesitation to use what is stereotypically known as a “squatty potty” — life was remarkably easy to adjust to. In the past four months, I have been coasting through many of the major historical cities of China, from Beijing to Nanjing, from Xi’an to Jinan. Yet about a month ago, I decided it was time to see some of China’s more natural landscapes, so I booked myself a ticket to Yun’nan. What I found there was something far more difficult to adjust to than belligerent throngs of Chinese white-collar workers and noisome public bathrooms. What I found there was gāoshān bìng (高山病), otherwise known as altitude sickness.

First, however, a note on Yun’nan. Literally meaning “south of the mountains of the clouds,” Yun’nan is a province in southwestern China, bordering Tibet and countries such as Vietnam and Laos. With mountainous terrain in the west and karst topography and a diverse network of rivers in the east, Yun’nan is a tourist hotspot with some of the most amazing scenery in China. My particular trip took me from Kunming through Dali to Lijiang, the last city being more than 2,400 meters (8,000 feet) above sea level. Little did I know that 2,400 meters is exactly where altitude sickness begins. By the time I hit some of the higher altitude spots of Lijiang, I had my head between my knees and was taking in great gulps of air, completely incapable of enjoying the startlingly blue skies and white-capped mountains outside the car window. The only thing overriding my profound disappointment in my own constitution were thoughts of how to make the nausea stop.

What exactly was happening to me? On top of Jade Dragon Snow Mountain (elevation approximately 5,000 meters or 16,404 feet), the atmosphere’s elemental composition does not change, yet its air pressure does. That is, while the air was still 21% oxygen and 78% nitrogen, the absolute number of molecules per liter was smaller. Therefore, each breath I took in contained less oxygen than I would normally get at sea level. The result of the lack of oxygen on my body was headaches and nausea during the day and insomnia at night. All these symptoms were nothing, however, compared to the shortness of breath I felt upon climbing a short set of stairs to the second floor: Think very old woman casting aside her walker and climbing a small mountain in a few minutes and you’ll get a sense of how incapable I felt.

Yet by the end of my tour around Yun’nan and Jade Dragon Snow Mountain, I was enjoying the sights, all thoughts of altitude sickness forgotten. Unlike some of my travel buddies, I hadn’t taken acetazolamide, a medication that acidifies blood and drives ventilation and acclimatization. Instead, I had waited and within a few days, my body had adjusted. Specifically, chemoreceptors near the carotid artery along my throat — called carotid bodies — had sensed the decrease in the partial pressure of oxygen and sent a message to my central nervous system telling it to increase the rate of ventilation. Moreover, my red blood cell and hemoglobin count had already begun to increase, helping me to make the most of each breath I drew in. With more red blood cells and more efficient hemoglobin, more molecules of oxygen per breath could be bound, transported, and eventually delivered to needy tissues.

So what should you do the next time you find yourself on a large precipice more than 2,400 meters above sea level? If you aren’t equipped with a handy prescription for acetazolamide and a Rite Aid around the corner, then here are some more traditional remedies:

Happy climbing!