Case Studies – Temporary Climate Solutions

Cleaning the air in Trinity Buildings After 9/11

On September 11, 2001, millions of Americans watched in horror as New York City’s twin World Trade Center towers collapsed. No image was longer lasting than the horrific plume of smoke and dust that spewed above the city and hung above the skyline for more than a week.

“Ground Zero” quickly became a term that all Americans would recognize as the site of the giant ruin left in place of the fallen towers. As a convoy of trucks began to clean up “Ground Zero,” many buildings adjacent to the disaster zone faced a different kind of recovery.


While buildings did not suffer substantial physical damage, many structures surrounding “Ground Zero” were contaminated by the giant cloud of smoke and dust that had filled the air for days after the attack. The Trinity Buildings located just one block from “Ground Zero,” were among them.

At 111 and 115 Broadway, the Trinity Buildings had been immersed in a giant cloud of smoke, dust, and debris for days after the destruction of the two towers. The north side of 115 Broadway, which faced the collapsed buildings and had windows broken by flying debris, the buildings were not damaged by the event.

“The buildings were saved from severe smoke damage,” said Larry Waltemire, Polygon Regional Manager, “because management turned off the HVAC system after One World Trade Center was hit by the first aircraft. By doing so, the system wasn’t running during the collapse, and thus did not draw in additional smoke and dust.”

Despite the fast work of the property managers, clouds of smoke and dust were forced into the structures. This left a serious concern for the health of the buildings’ workers and the cleanliness of the office space.


We were called to provide extensive smoke neutralization, sanitization, and deodorization before tenants could reoccupy the buildings. After an analysis of the situation and discussion with building management, our team addressed the problem with a two-part process.

First, we set up air scrubbers on 20 floors of the building and then built an air-moving system to circulate the interior air through them. The air scrubbers contain both carbon and HEPA filters, which can remove extremely small particles from the air.

Second, to eliminate the smell of smoke, wet and dry fogging processes were used. A chemical agent is turned into a “fog” by application equipment. The dry fog permeates the entire indoor space, reaching deep into even “the nooks and crannies” of the sealed area, neutralizing the smell of smoke. In a supplementary process, Polygon technicians also used a wet fog spray to eliminate the smoky odor.

“Our services helped return the air to a cleaner, more pleasant condition for returning workers,” said Larry Waltemire. “Building management felt that this helped make tenants feel safe when reoccupying their offices.”

During the same period, Polygon used a similar air scrubbing process at the Pentagon. There, Polygon both reversed significant water damage and decontaminated the air.


Reduce Microbiological Problems - Smoke Polygon has extensive knowledge of abating post-disaster microbiological problems. The growth of many bacteria and molds can be stopped if fast action is taken. This can save millions of dollars and keep building occupants safe.

Preventative Measures - Understanding the dangers of unhealthy air quality can help take preventative measures and protect employees. Our ExactAire system helps continuously monitor conditions and understand how they change over time.