Sand and dust shroud North China’s Tianjin municipality on Wednesday. PM10 concentrations in the city exceeded 500 micrograms per cubic meter that day, according to Tianjin Eco-Environmental Monitoring Center. Photo: VCG

Sand and dust shroud North China’s Tianjin municipality on Wednesday. PM10 concentrations in the city exceeded 500 micrograms per cubic meter that day, according to Tianjin Eco-Environmental Monitoring Center. Photo: VCG

Residents exercise amid the pollution Wednesday in Anda, Northeast China’s Heilongjiang province. Visibility in parts of the city fell to less than 50 meters due to the thick haze. Photo: VCG

People wearing face masks walk across a street in Beijing’s central business district (CBD) on Wednesday. The capital’s PM10 concentration reached 419 micrograms per cubic meter as of 3 p.m. that day, according to the Beijing Municipal Ecological and Environmental Monitoring Center. Photo: VCG

A woman wearing a face mask and goggles walks around Beijing’s CBD. Photo: VCG

Sand and dust obscure the sky in Beijing’s Chaoyang district. Photo: VCG

China Zun, an iconic skyscraper in Beijing’s CBD, disappears from the skyline in the thick haze. Photo: VCG

Sand and dust shroud the sky over Jinshanling Great Wall in Chengde, North China’s Hebei province, on Wednesday. PM10 concentrations across Hebei reached more than 700 micrograms per cubic meter that day, according to the Ministry of Ecology and Environment. Photo: VCG

Border police inspect freight trains in the pollution at an entry and exit border checkpoint in Erenhot, North China’s Inner Mongolia autonomous region, on Tuesday. Photo: IC photo