BEIJING/NEW DELHI, Safar 18, 1437, November 30, 2015, SPA -- The capitals of the world's two most populous nations, China and India, were blanketed in hazardous, choking smog on Monday as climate change talks began in Paris, where leaders of both countries are leading participants, Reuters reported. China's capital Beijing maintained an "orange" pollution alert, the second-highest level, on Monday, closing highways, halting or suspending construction and prompting a warning to residents to stay indoors. The choking pollution was caused by the "unfavourable" weather, the Ministry of Environmental Protection said on Sunday. Emissions in northern China soar over winter as urban heating systems are switched on and low wind speeds have meant that polluted air has not been dispersed. In New Delhi, the U.S. embassy's monitoring station recorded an air quality index of 372 - which put air pollution levels well into "hazardous" territory. A thick smog blanketed the city and visibility was down to about 200 yards (metres). Air quality in the city of 16 million is usually bad in winter, with thousands of coal fires lit by the poor to ward off the cold. However, the government has not raised any alarm over the current air quality and no advisories were issued to the public. Thirty thousand runners took part in a half marathon at the weekend, when pollution levels were just as high. --SPA 13:39 LOCAL TIME 10:39 GMT www.spa.gov.sa/w