People riding motorcycles cover their faces with cloth in Hai Phong city, northern Vietnam, May 30, 2015. A heat wave with temperature constantly rising over 40 degree Celsius hits northern Vietnam, which has badly affected local people's life. (Xinhua/VNA)

Farmers cover their faces with cloth in Hai Phong city, northern Vietnam, May 30, 2015. A heat wave with temperature constantly rising over 40 degree Celsius hits northern Vietnam, which has badly affected local people's life. (Xinhua/VNA)

Sick children struck by the heat receive treatment at a hospital in Hai Phong city, northern Vietnam, May 30, 2015. A heat wave with temperature constantly rising over 40 degree Celsius hits northern Vietnam, which has badly affected local people's life. (Xinhua/VNA)

Sick children struck by the heat receive treatment at a hospital in Hai Phong city, northern Vietnam, May 30, 2015. A heat wave with temperature constantly rising over 40 degree Celsius hits northern Vietnam, which has badly affected local people's life. (Xinhua/VNA)

Sick children struck by the heat wait to receive treatment at a hospital in Hai Phong city, northern Vietnam, May 30, 2015. A heat wave with temperature constantly rising over 40 degree Celsius hits northern Vietnam, which has badly affected local people's life. (Xinhua/VNA)