Hazardous Debris
Studies have shown that this was indeed among the worst-case scenarios as the impact emitted more hazardous debris into the upper atmosphere and scattered it everywhere which led to the ultimate fatalities. This is what eventually caused a nuclear winter.
What Is A Nuclear Winter?
And what is a nuclear winter, you may ask? Well to put it simply, its something extremely severe and extended. The climatic cooling effect is speculated to take place after a widespread firestorm. Scientists suggest that all the fires were caused by the asteroid that slammed Earth.