The deadliest smogs in history

19th century: London, England - The overall death rate is unknown, but one event in particular, in 1873, led to the deaths of 268 people due to smog-induced bronchitis.

1953 and 1966: New York City - The New York Times reported that in the 1960s, deaths from pulmonary emphysema and chronic bronchitis skyrocketed in the city.

1948: Donora, Pennsylvania - It's estimated that 43% of the local population suffered long-term health effects following the smog.

2013: China - In January 2013, the country was hit by an earlier smog incident. The haze was so thick that it could be seen from space.

1948, 1956, 1957, 1950, 1962: London, England - London has been plagued by many deadly smog events over the 20th century.

1991: London, England - Official figures estimate that the 1991 smog killed at least 160 people in the capital, after they were exposed to unsafe levels of nitrogen dioxide in the air.

1930: Meuse Valley, Belgium - Between December 3 and 5, the lack of wind and thick mist trapped all the air pollution coming out of the factories, killing 60 people as a result.

2016: China - The air pollution levels were 50 times higher than what the World Health Organization deemed safe.

2005: Malaysia - In 2005, the country was hit by a thick haze caused by smoke originating from wildfires in the neighboring Indonesian island of Sumatra.

2010: Moscow, Russia - It is estimated that around 104,000 people fled Moscow during this period. Still, by October the stats pointed to 56,000 more deaths.