10 Years after 9/11: How Photoluminescent Path Markings Are Making Buildings Safer
(Note: PSA member Jim Armour authored an article in 2011 for the anniversary of September 11 terrorist attached that was published in the Life Safety Digest. We reprint it here with his permission. Also, the Canadian study Armour mentions is also available through a link on the PSA’s website. Click here to see this page.)
Photoluminescent Exit Path Markings: Now a Part of the 2009 and 2012 International Building Code and International Fire Code and NFPA 101 Life Safety Code
By Jim Armour
We recently observed the 10th anniversary of the attack on America that will be forever known as 9/11. That tragic day saw the loss of nearly 3,000 innocent lives from New York City to Arlington, VA to a farm field in Shanksville, PA. The City of New York reported 2,749 deaths that day; more than 1,500 of the fatalities were building occupants of the World Trade Center complex. The good news from that terrible day was that over 16,000 people safely evacuated the twin towers – thanks, in part, to the Photoluminescent Exit Path Markings that glowed in the dark when all emergency electrical lighting failed.
The US National Institute of Standards and Technology (NIST) investigation of the collapse of the World Trade Center Towers yielded 31 recommendations to improve the safety of high-rise structures and emergency responses. These recommendations resulted in 23 changes to the 2009 editions of the International Building and Fire Codes and another 17 changes were adopted to the 2012 editions. The 2009 International Buildings Code and the International Fire Code has already been adopted by 22 states and many more municipalities and 12 more states will complete their adoption process early next year. One of the recommended changes was to add photoluminescent exit path markings within the emergency escape stairwell enclosures of all buildings over 75 feet in height. This was noted in the NIST report as aiding and accelerating the occupant evacuation of the buildings prior to collapse.
One of the first documented studies on photoluminescent egress path markings vs. electrical lighting and its impact on the rate of occupant evacuation was performed by the National Research Council of Canada under the direction of Dr. Guylene Proulx in April 1999. Dr. Proulx’s research evaluated the speed of evacuation of building occupants under a controlled fire drill. Four identical stairwells in the same building were outfitted differently for evaluation.
Stairwell C.(see insert) Full Electrical Lighting – No PL Markings
Stairwell B.(not shown) Reduced Lighting @ 74 Lux – PL markings added
Stairwell D.(not shown) Reduced Lighting @ 57 Lux – PL markings added
Stairwell E.(see insert) No Electrical Lighting – PL markings only
The occupant’s speed of evacuation was timed by researchers in all stairwells during the fire drill. The results showed that the speed of evacuation in the standard lighted stairwell (C.) and the stairwell with no electrical lighting and only photoluminescent markings (E.) was statistically equal. The research was repeated in June of 2007 and the results were duplicated. Of note; the study also concluded that more was not better in this case. Stairwell G (see insert) was found to be over powering and delayed evacuation and Stairwell A.(see insert), with only “L” markings on the steps, did not provide adequate definition to the stairs and slowed evacuation.
The NIST study also documented the increased rate of occupant evacuation with photoluminescent egress markings. After the 1993 bombing of the World Trade Center complex, the Port Authority of New York and New Jersey added Photoluminescent Egress Markings to all emergency stairwells in the World Trade Center Towers 1 and 2. Although causalities in the 1993 bombing were significantly less than on 9/11, the loss of power due to the bomb blast was almost instantaneous. Because of this, it took more than 6 hours to totally evacuate the Twin Towers in the dark. Recognizing the need to improve the evacuation times, the Photoluminescent Exit Path Markings were added to improve egress rates in the event of another power failure. On September 11, 2001, the total elapsed time between the first airplane impact on the first tower until the collapse of the second tower was only 102 minutes. Even with the failure of the emergency back-up power systems more than 16,000 people escaped during that time, many in total darkness. The twin towers Photoluminescent Exit Path Marking Systems worked–even when the back-up electrical lighting systems failed.
Using the research from both these studies, the code committees developed the following requirement to place photoluminescent markings within the exit enclosures of buildings 75 feet tall or more upon all:
- Stair Treads & Landings
- Demarcation Lines
- Exit Door Markings & Directional Signage
- Obstruction Markings
Doors within the exit enclosure and final exit doors from the enclosure are required to have a 1” or 2” stripe around the door frame and the emergency exit symbol mounted on each door no more than 18” above the floor. Additionally, door hardware shall be marked with no less than 16 square inches of luminous material. This marking shall be located behind, immediately adjacent to, or on the door handle and/or escutcheon. Where a panic bar is installed, such material shall be no less than 1 inch wide for the entire length of the actuating bar or touchpad.
Placement and dimensions of markings shall be consistent and uniform throughout the same exit enclosure. Luminescent exit path markings shall be permitted to be made of any material, including paint, provided that an electrical charge is not required to maintain the required luminance. Such materials shall include, but not limited to, self-luminous materials and photoluminescent materials. Materials shall comply with either:
1. UL 1994, or
2. ASTM E 2072, except that the charging source shall be 1 foot candles (11 lux) of fluorescent illumination for 60 minutes, and the minimum luminance shall be 30 milicandelas per square meter at 10 minutes and 5 milicandelas per square meter after 90 minutes.
It is highly recommended that building owners use only products that have been tested and are listed with independent third party testing laboratories for compliance to these performance standards.
Installation of Photoluminescent Egress Path Marking Systems is not an overly difficult process and in many circumstances can be accomplished with the buildings maintenance personnel following the manufacturer’s installation instructions. However, most manufacturers will refer you to a Certified Installer in your local area that has received detailed installation training for their products. This includes proper surface preparation along with installation procedures to insure many years of maintenance free performance. The manufacturer’s Certified Installer will also be trained on proper location for the photoluminescent markings to comply with your local code officials requirements. (For a listing of photoluminescent manufacturers, click here)
With significant technological improvements in long-lasting glow-in-the-dark pigments and products, today’s Photoluminescent Exit Path Marking Systems offer a much higher performance in brightness and length of time for visibility at a significantly lower cost. With proper installation most high-rise buildings can be retrofitted for pennies a square foot and building owners can enjoy maintenance free performance for more than 25 years.
In these difficult economic times the question is often asked, “Are these building requirements really necessary?” America has the best record for preserving life and property of any country in the free world. That’s because we continually seek to learn from disasters, natural or man made, to improve our living environment. Disasters like the MGM Grand Fire in Las Vegas, NV caused the development and installation of moveable expansion joint fire barriers to contain and compartmentalize smoke and fires in commercial structures. The high rise fire at One Meridian Plaza in Philadelphia, PA that took the lives of three fire fighters who were disoriented and over powered by dense smoke lead to the addition Stairwell Identification signage to our codes. The collapse of the World Trade Center Towers caused the addition of Photoluminescent Exit Path Markings to aid occupants in rapid evacuation and First Responders in accessing the building, even in total darkness. May we always strive to provide the highest degree of Fire and Life Safety in our commercial structures?
Jim Armour serves as Executive Vice President of the Photoluminescent Safety Association and is a member of the Board of Directors. In 2012 Jim retired from Balco Inc. as President and Chief Executive Officer. Balco is an industry leader in the manufacturer of photoluminescent exit path marking systems and expansion joint fire barrier systems serving the commercial construction market and a founding member of the Photoluminescent Safety Association.