2015 saw Beijing’s first-ever red alerts, and the city’s residents couldn’t be more concerned over the health threat posed by air pollution. However, Beijingers may be living in good company if one were to believe the claim that several ancient Chinese emperors died from smog.

According to a Xinhua report, Macao-based heart surgeon, Dr. Tan Jianqiao, claims that ten Chinese emperors, including Kangxi and Qianlong, the second and sixth Emperors of the Qing dynasties, respectively,  died from smog while living in ancient Beijing.

In his book, Unheard Anecdotes of History: Medical Treatments that You’ve Never Heard About, Dr. Jianqiao argues that smog was a severe problem in ancient Beijing, and ten emperors died as a result.

Dr. Jianqiao poured through the imperial records and found that, during the twelfth lunar month of the sixth year of the Yuan Dynasty, “the fog that enshrouded the capital was so thick that it blocked out light from the sun for days, and the gates of the capital were hidden by the haze.” The smog was even worse during the Qing Dynasty, during which a “fog disaster” struck the capital in 1721, shrouding the city and blocking out the sun.

In 1856AD, the sixth year of Emperor Xianfeng’s reign, the imperial records show that, “upon entering the winter, snow was light but the fog was thick. Dust, rain, wind and fog all descending upon the capital, especially in the areas of Changping and Wanping.”

Chinese historians have been trying to prove that air pollution in Beijing is nothing new. It has been suggested that ancient China’s smog was worse than today’s, primarily because scholars at the time didn’t have access to modern technological devices for analysis.

Although a Chinese term exists for “air pollution”, many Chinese media eschew the term in favor of 雾霾 (wùmái), a combination of two words that describe the naturally occurring weather phenomenon of “fog” and “haze”. As such, wumai is often used to downplay the severity of air pollution, particularly when Chinese media write wumai as just one Chinese character.

So while wumai is a new term that reflects the growing concern of Beijing residents over the health risks of air pollution, these two Chinese terms have existed individually in Chinese language for perhaps thousands of years, and now have been used by Dr. Jianqiao as synonymous with air pollution in an industrialized and urbanized China.

The way Dr. Jianqiao explains wumai is that wu comes from natural sources, while mai comes from man-made sources. The reason smog could exist in ancient China is because of dust of the nearby desert as well as the bustling industry of the capital.

The Xinhua report doesn’t provide any direct proof that air pollution killed the ten Chinese emperors, as Dr. Jianqiao claims, but it does explain that Beijing’s air pollution is a natural extension of the capital’s past. Dr. Jianqiao argues that, as Beijing became the center for politics and culture, and as its population increased, so too did its PM 2.5 levels.

There will almost certainly be academic controversy about the doctor’s theory.  Professor Wu Dui, from the Atmosphere and Environment Safety and Pollution Control Research Auxiliary Center at Jinan University, pointed out that the dust storms of the past were natural phenomenons, while today’s “grey fog” was caused by man-made emissions. Dui also pointed out that Beijing itself is surrounded by mountains, allowing for heavy pollution to settle on top of the city.

We’d imagine that the emperors of old would be impressed with modern Beijing and its large-scale factories, extensive transportation network, and tens of millions of residents. And yet, they’d probably be concerned that these advancements caused the air pollution that possibly killed them.