Exposure to carbon dioxide / carbon monoxide for several hours can cause collapse, coma and even death. It also causes headaches, drowsiness, dizziness and nausea. Carbon monoxide in heavy traffic causes headaches, drowsiness and blurred vision; in large doses, can cause death.
Sulphur dioxide irritates the respiratory tissues; causes bronchitis.
Nitrogen dioxide can irritate the lungs, aggravate asthma and increase the susceptibility to respiratory infections like influenza.
Suspended particles aggravate respiratory tract, leading to bronchitis and asthma. Prolonged exposure can cause cancer.
Many volatile organic compounds (eg: benzene and formaldehyde) and toxic particulates (eg: lead and cadmium) can cause mutations, reproductive problems or cancer.
Repeated inhalation of ozone causes coughing, chest pain, breathlessness and irritation of the eye, nose and throat.