Breathing unfiltered air from rush-hour traffic can significantly increase passengers’ blood pressure up to 24 hours later, revealed an alarming study, even as New Delhi and the nearby regions of Gurugram, Ghaziabad have been gripped with bad air quality for about a month.

Long-term exposure to traffic-related air pollution -- a complex mixture of exhaust from tailpipes, brake and tire wear, and road dust -- has been linked to increased rates of cardiovascular disease, asthma, lung cancer and death.