The health effects of outdoor air pollution can only be assessed after long-term monitoring and quantitative data analysis, a spokesman for the country's top health authority said.

Mao Qun'an, spokesman for the National Health and Family Planning Commission, said in a news conference on Tuesday that the authority's monitoring of the health effects of outdoor air pollution could yield results only after a long period. The monitoring began in late 2013.

In October, the authority announced a plan for establishing a monitoring network to study outdoor air pollution's effects on health in the next three to five years.