The Environmental Ministry ordered the Jerusalem Central Bus Station to install a barrier between the bus platform and the building's interior, after finding the air in the bus station is extremely polluted. According to tests conducted over the past months, in more than half of the samples, the air was four or five times more polluted than levels considered acceptable. On one occasion, the air had 17 times the acceptable level of air pollutants. Most of the problem stems from the lack of ventilation in the areas where passengers get on and off the buses, the study found. The Environmental Ministry said they had received many complaints from the public about the air quality in the CBS. A physical barrier, including an extra set of doors between the area where passengers get on and off the bus and the interior of the building, would significantly improve the air quality in the building, the Environmental Ministry said.