Diwali, the festival of lights, is a festival of noise and smoke in Delhi, thanks to the extensive use of firecrackers that adds tonnes of toxic smoke to the city's air. According to System of Air Quality, Weather Forecasting and Research (SAFAR), an agency of the Ministry of Earth Science, pollution levels in the national capital are expected to be "severe" on Diwali night. Those with heart and lung diseases have been advised to stay indoors.