My husband, a filmmaker, works for Verizon and he was at Ground Zero the week following the disaster documenting the process of getting communication lines running again so the stock market could function.
Everyone described the smell and taste of the ash which remained in the air for days and weeks. We could see the plume of smoke in Westchester for days on end. And we were all aware that there were few bodies recovered - what remained of the 3000 odd people was the ash that workers and everyone near the site breathed in.
This piece also describes on a gut level the magnitude of the impact of those planes - how people vaporized and how it was beyond words to describe.