Please explain to me the dangers of breathing in the exhaust from cars and buses and does it cause damage to the brain even in ventilated areas?

Air pollution . Several small particles are found in polluted air. Exhausted air from combustion engine also contains several acids, small hydrocarbon particles, and most dangerously carbon monoxide. If you breath air that has a high carbon monoxide concentration, it interferes with oxygen transport in your blood, hence it might cause death. Chronic exposure to such pollutions might cause asthma, sinusitis.
Generally not. Brain injury may come from deliberate inhalation of large amounts (huffing or bagging to get high). You may notice eye irritation or cough (especially if you have asthma) but if the area is ventilated the dose of exhaust fumes should be too low to cause brain injury.