The sky in some suburban areas in Hanoi has been covered by smoke in the past few days.

The smoke is caused by dried straw and grass burnt by farmers.

The thick smoke covered the sky hinders the vision of drivers.

According to medical experts, smoke can cause respiratory diseases.

Piles of straw and grass smolder all day and night, blowing smoke into the sky.

Farmers said they now cook by gas. They don’t know what to do with straw so they have to burn it to have ash to fertilize trees.