Air pollution in China may be contributing to low levels of happiness among the country's urban population, reveal researchers from the US.
In a paper published in the journal Nature Human Behaviour, a research team led by Siqi Zheng, Faculty Director of MIT China Future City Lab, discovered that that higher levels of pollution are associated with a decrease in people's happiness levels in the country.
The team used information on urban levels of ultrafine particulate matter - - PM 2. 5 concentration - - from the daily air quality readings released by China's Ministry of Environmental Protection.
To measure daily happiness levels for each city, the team applied a Machine Learning (ML) algorithm to analyze the 210 million geotagged tweets from China's largest microblogging platform, Sina Weibo.
The tweets cover a period from March to November 2014.
For each tweet, the researchers applied the machine - trained sentiment analysis algorithm to measure the sentiment of the post.
They then calculated the median value for that city and day, the so - called expressed happiness index, ranging from 0 to 100, with 0 indicating a very negative mood, and 100 a very positive one.
Finally, the researchers merged this index with the daily PM2. 5 concentration and weather data.
They found a significantly negative correlation between pollution and happiness levels.