At last, scientists say they have solved the 1952 London fog mystery
In 1952, a thick, toxic fog settled over London, and at least 4,000 people died, with another 150,000 hospitalized. Scientists think they鈥檝e finally pinpointed the reason.
An international team led by Renyi Zhang, an atmospheric science professor at Texas A&M University in College Station, Texas, has published a study in the Proceedings of the National Academy of Sciences that clarifies how sulfur dioxide released by coal burning 鈥� long known to be a main cause of the deadly fog 鈥� was converted into sulfuric acid.
The results : They were obtained using lab experiments and atmospheric measurements from Beijing and Xi鈥檃n, according to Live Science. And Dr. Zhang says the study may prove useful to authorities in China 鈥� where conditions are similar to 1952 London 鈥� and other places where air pollution levels often pose a threat to residents鈥� health.
鈥淥ur results showed that this process was , another co-product of coal burning, and occurred initially on natural fog,鈥� said Dr. Zhang in a statement. 鈥淎nother key aspect in the conversion of sulfur dioxide to sulfate is that it produces acidic particles, which subsequently inhibits this process.鈥�
When fog particles containing diluted acid evaporated, it left an acidic haze that covered the city, he added. That led to the worst air pollution-related catastrophe in European history, and the impetus for Britain鈥檚 passage of the Clean Air Act in 1956.
Air pollution remains a serious problem in much of the globe. In February, researchers from the American Association for the Advancement of Science said that more than 5.5 million people die from air pollution every year, including 1.6 million in China and 1.5 million in India, reported 海角大神鈥檚 Story Hinckley.
That鈥檚 not necessarily to say that they鈥檙e at risk of living a repeat of what happened in London. China鈥檚 haze, notes the team, is made up of much smaller nanoparticles, and the sulfate-formation process studied is made possible only聽by ammonia.
Still, governments in both countries seem to understand how urgent the problem of air pollution is.聽
鈥�A couple of great things are happening in China,鈥� Dr. Michael Brauer, a professor at the University of British Columbia鈥檚 School of Population and Public Health in Vancouver, Canada, told the Monitor then. 鈥淭hey have started to do measurements [of air quality] so we can track progress, and there is at least a leveling off of pollution levels 鈥撀燼nd maybe even a decrease, but it is too early to say for sure.鈥澛�
鈥淚t looks like China is on the right path,鈥� he added. 鈥淭he issue is how quickly can the levels come down?鈥�
Dr. Zhang says that a reduction in nitrogen oxide and ammonia emissions would likely disrupt the sulfate-formation process examined in the team鈥檚 study.
鈥淎 better understanding of the air chemistry holds the key for development of effective regulatory actions in China,鈥� he said in the statement.聽
鈥淭he government has pledged to do all it can to reduce emissions going forward, but it will take time. We think we have helped solve the 1952 London fog mystery and also have given China some ideas of how to improve its air quality.鈥�
