Beijing has required all its urban construction sites to install cameras by the end of June to assess how constructors' practices add to the capital's smog.

Based on the pictures taken by the cameras, the municipal commission of housing and urban-rural development will punish companies that use unqualified trucks to carry earth or allow outdoor construction to continue in heavily polluted days.

In addition, all construction companies will be required to use qualified fully enclosed vehicles to carry earth from July 1, according to the commission.

Among a spate of measures introduced since the start of April to control pollution from construction sites in the Chinese capital, the commission has also required contractors to place a special fund for dust control in an officially appointed bank account before construction begins.

The municipal government announced in 2012 that construction companies would be banned from submitting bids for new projects for six months if their existing projects were found to have "irregularities," including large dust emissions and spilled construction materials.

Beijing has tightened management on its construction sites, a major source of dust, as the capital has frequently been choked by serious smog since 2013.

Construction sites are asked to stop work in days with poor air quality. Endi