Ambient pollution is not a Delhi problem alone. The air quality index reports danger levels many times the health limit across North India. From the plains of Punjab to Bihar, that's roughly 400 million people.
India's "poor" warning begins above an AQI of 200 and says breathing discomfort could be caused to most people on prolonged exposure. There is no separate warning for children. What stands out is that the US warning doesn't differentiate between healthy or unhealthy kids.
Anyone reading this - in English on a phone/tablet/computer - most likely has a lifestyle that will need more than just one Earth to sustain if all seven billion people followed it. Mine, to my shock, was over four planets. Carbon Footprint tests are easily found on the net and are good and guilty fun.