A large dust storm has travelled across the Phoenix, Arizona area causing health problems and road closures.

The brown cloud of dust swept across the valley and caused roads to be closed due to the poor visibility.

Scientists are becoming increasingly concerned about dust clouds as they harmfully pollute the air with particles that lead to breathing and other health problems.

Dust storms have been common in the Phoenix area this summer and scientists have said they are expecting more frequent and larger events in light of the warmer climate.