Mayors and other municipal officials should develop “urban heat maps” to identify and protect those most vulnerable to high temperatures, World Health Organization (WHO) official Maria Neira urged on Wednesday.

Many people in urban areas stifling under heat waves cannot afford cooling systems while conditions for outdoor workers not protected by legislation have become dangerous, added Neira, WHO Director of Public Health, Environmental and Social Determinants of Health.

She told the WHO’s weekly media briefing that people needed to be educated to recognize the signs of heat exhaustion and heat stroke.