A thick blanket of smog engulfed the capital, air quality plummeting to very poor category on Thursday and Friday. As people of Delhi battled the toxic air with respiratory problems on the rise, the Central Pollution Control Board has now identified at least 13 hotspots. At least two of them will fall in the 21 km half marathon route. Despite that, the capital will host its annual half-marathon for the 15th time. The organisers claim they will clean up the air by spraying and with the help of these specially designed machines.