Over 80 percent of people living in urban areas monitoring air pollution are living with poor air quality levels that exceed limits set by the World Health Organisation (WHO).
In a news release on Thursday, the WHO added that 98 percent of cities in "low and middle income countries" with over 100,000 people did not meet the WHO's guidelines for air quality. For those living in high income countries, this dropped to 56 percent.
The WHO said that a decline in urban air quality would increase the risk of lung cancer, heart disease, stroke as well as "chronic and acute respiratory diseases" such as asthma.
Air pollution was described as a "major cause of disease and death" by Flavia Bustreo, the WHO's assistant director general for family, women and children's health.