How did the ancients know about smog?

Haze is called "haze disaster", "rain haze", "wind haze" and "soil rain" in history, and it has been recorded in many historical materials.

At present, the earliest record of foggy days can be traced back to the Yuan Dynasty. According to the records of Yuan history, in March of Yuan (1329), because there was no snow in winter and little rain in spring, the weather was unusually dry, which led to "rainy soil and haze" and "it is difficult to see the sun when you are faint, and passers-by hide your face". In the twelfth lunar month in the sixth year of Yuan Dynasty (1340), "most of the fog locks, and the sun has not been seen for many days, and the city gate is hidden in the wind and mist". It can be seen that the two "smog disasters" recorded in the history books of the Yuan Dynasty lasted for a long time and the visibility was very low.

In the Ming and Qing Dynasties, "Haze and dust accumulation are hard to see passers-by"

In the Ming dynasty, the records of "haze disaster" gradually increased.

In the early spring of the fourth year of Ming Chenghua (1468), the Record of Ming Xianzong recorded: "This year, from spring to summer, the weather was cold and miserable, and the wind was overcast ... The yellow fog covered the sun for two days, and the stars were not seen day and night." In the seventeenth year of Chenghua in the Ming Dynasty (148 1), in April, "the wind blew wildly for several days, and the dust covered the sky." In the 21st year of Chenghua (1485), "At the end of the month, the capital was overcast and scattered from morning till night." There were dozens of similar "haze disasters" in Beijing in the Ming Dynasty.

There were also many "haze disasters" in the Qing Dynasty. Sixty years of Kangxi (172 1) "Today's (test) issue is covered with yellow fog and misty clouds cover the sun. With such a strong wind, the list will be damaged. " In the fifteenth year of Jiaqing (18 10), "after the capital entered the twelfth lunar month, fog and haze rose from time to time, and both Wanping and Daxing were reported." In the sixth year of Xianfeng (1856), "since the winter, when there was little snow and more fog, the capital was in Changping and Wanping." In short, the "smog disaster" will come to Beijing every few years, mostly in winter and spring.

In ancient times when science was underdeveloped, people knew little about smog, so the degree, concentration, scope and harm of smog could only be recorded by feeling, only the disaster situation. There is no record about how to prevent the "smog disaster".