How 9/11 Shifted HVAC Focus to Indoor Air Quality

The useful part

October 1, 2026 The terrorist attack of 25 years ago in New York City brought attention to an issue that remains a priority for HVAC and building science professional: healthy IAQ. The fall of the World Trade Center's twin towers, after hijackers flew planes into them, raised massive clouds of contaminant-laden smoke and dust. The attacks destroyed the seven-building World Trade Center complex and caused partial or total collapse in several other major buildings nearby.

How it works

• In the months following, The ACHR NEWS followed 9/11-related IAQ developments.
• Ask ACHR NEWS → "There is not a whole lot of guidance to address the types of issues we are dealing with now," said James Woods of the HP-Woods Research Institute.
• KEYWORDS: air filtration ASHRAE standards HEPA filters IAQ Share This Story Looking for a reprint of this article?
• Within two weeks of the attacks, the magazine quoted Jim Pearson, chairman of the Mechanical Systems Hygiene Institute, who was concerned about other buildings in Lower Manhattan being infiltrated by...

What to take from it

ASHRAE panelists offered recommendations to building owners and managers for limiting the risks posed by contaminated air. By January 2002, members of the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) were discussing an ASHRAE report, Risk Management Guidance for Health and Safety Under Extraordinary Incidents, during the AHR Expo in Atlantic City. Turpin Related Articles HVAC Industry Needs to Solve the IAQ Puzzle See More Schools Pay More Attention to IAQ See More A Layered Approach to IAQ See More Related Products See More Products ACHR NEWS August 11, 2025, Issue See More Products Related Directories Dexen Industries Inc.

Example or evidence

• ASHRAE revisited the issue again during its annual meeting that July in Honolulu, during which members discussed what kinds of airborne particles had been found at and near Ground Zero.
• A big building will be filled with tons of particulates," he said.
• "This is a situation that none of us have ever had to face before," Pearson added.

Details worth keeping

HVAC systems will have to be decontaminated as well, Pearson said. The report was prompted by 9/11 as well as by the anthrax attacks that took place in the fall of 2001. Looking for quick answers on air conditioning, heating and refrigeration topics?

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