About 93 percent of the Lebanese capital's residents are exposed to high levels of air pollution, a study presented in Beirut said Monday.

The study, which was carried out by researchers from the American University of Beirut, Saint Joseph University and Lebanon 's National Center for Scientific Research, also noted that the overall cost of air pollution to health exceeds 10 million U.S. dollars a year.

The study warned that air pollution levels in Beirut were higher than acceptable World Health Organization (WHO) standards and were subject to a yearly increase.

The study, which was conducted from 2008 to 2010, gathered air samples from monitoring stations all around Beirut and found out that the average annual concentration of the harmful air pollutant nitrogen dioxide, reached 58 micrograms per cubic meter in 2010.

According to WHO, the maximum allowable concentration is 40 micrograms per cubic meter.

Modes of transport, dusty streets and inadequate urban management were identified as the biggest contributors to the increasing air pollution of Beirut.