Stay indoors on hazy days, experts advise

To run or not to run on a smoggy day?

Harmful PM 2.5 particles in Beijing hit more than 320 micrograms per cubic meter on Sunday, at least 13 times the safety limit set by the World Health Organization.

Wang Guangfa, director of the respiratory medicine department of Peking University First Hospital, told China Daily that people should avoid going outside in such heavy smog, let along running a marathon.