The World Trade Center towers in New York City fell on 9/11/2001 which caused the buildings to collapse into big clouds of dust which were expelled all throughout Lower Manhattan. The majority of this dust was made of a concrete, gypsum and synthetic vitreous fibers that were rapidly spread about the city by wind and other physical sources. Large amounts of this dust was inhaled and swallowed which caused both physical and chemical irritation of respiratory and gastroesophageal linings. These adverse affects were felt by a wide range of people but most intensely felt by rescue workers, cleanup workers, residents of the surrounding areas and office workers. As a result of the large amount of chemicals now present in their air, the city of New York ran numerous tests to check the air quality and determine the chemicals that had been dispersed throughout the city. A major finding of the studies conducted was that there was an increase of respiratory and GI tract health effects along with low birth weights and birth defects of children who were exposed in utero and an increase in the cases of reported PTSD. In the future, the research has concluded that there is a concern about an increase in cancer rates along with an increase in birth defects and negative cardiovascular responses.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4686342/