Economy When smog travels from South Asia to the United States Updated : September 17, 2019 04:33 PM IST Ozone alerts in the United States advise people to skip car trips and against prolonged exposure to high levels of the lung-damaging greenhouse gas on specific days. The role of foreign air pollutants, such as those that blow from southern Asia, in contributing to local pollution levels in the United States has stirred debates. While ozone from other countries does impact the surface air of the USA, it is not the major contributor to ozone pollution events. Subscribe to Moneycontrol PRO at just Rs.33/- per month for the first year. Use code SUPERPRO. Limited period offer. Available on Web and Android.