Controlled Fire Study Finds High Levels of Airborne Chemicals
A NIOSH fire study found high levels of airborne chemicals from synthetic materials in modern-day furnishings, highlighting the importance of protection for firefighters. Thinkstock
What do plastic, polyester, and foam have in common? They are synthetic materials found throughout most modern homes in everything from toys to furniture to appliances. Unlike wood, cotton, and other natural materials, synthetic materials are made in laboratories through chemical processes.
During a fire, these chemicals can burn hotter and faster, and produce more toxic smoke than natural materials. Evidence suggests that work-related exposure to these toxicants among firefighters corresponds to an increased risk of acute cardiovascular events and cancer.
To understand the risk of exposure from residential firefighting, NIOSH investigators and university and industry partners measured hazardous air emissions during different stages of firefighting. The investigators set 12 separate fires in safe and controlled settings to simulate residential firefighting conditions. This included furnishing the structures with modern fixtures. Six of the fires involved firefighters entering through the front door of the building to extinguish the fire. The others involved firefighters first dousing the fire through a bedroom window before entering through the front door.
Investigators then collected air samples for several chemicals, including benzene and other volatile organic compounds, poly-cyclic aromatic hydrocarbons, and hydrogen cyanide. For comparison, they tested air from three areas: 1) inside the structure during active fire; 2) inside the structure after fire suppression, also known as overhaul, when firefighters search for and extinguish any smoldering items; and 3) outside the structure near exterior crew-members like the incident commander. In addition, they took personal air measurements associated with job types in all three areas: fire attack, victim search, overhaul, outside ventilation (help vent smoke from structure), and command/pump operator tasks.
In general, median personal air measurements collected from interior crew-members were substantially higher than the recommended exposure limits for short-term exposure for the chemicals measured. Significant differences occurred by job type, with search and attack exhibiting the highest levels of chemical exposure. The maximum levels recorded for hydrogen cyanide for firefighters assigned to attack, search, and outside ventilation were higher than levels considered immediately dangerous to life and health. Outside ventilation crews may not always wear respiratory protection and as a result could breathe in the chemicals that were measured. Even though search and attack firefighters wear self-contained breathing apparatus to protect their lungs, exposure could also occur via the skin, either through direct contact or when removing contaminated gear after the fire.
Area air measurements also showed that the median amount of several chemicals tested was higher than recommended short-term exposure limits. Even in the area outside the burning structure, where workers like the incident commander typically do not wear respiratory protection, area air measurements downwind of the fire were higher than naturally occurring levels. These results highlight the importance of wearing self-contained breathing apparatus, even when firefighters are assigned to post-fire suppression jobs or exterior operations. They also show the need for establishing command centers upwind of a fire or, if that is impossible, wearing self-contained breathing apparatus for protection against airborne chemicals, according to the study published in the Journal of Occupational and Environmental Hygiene.
More information is available:
Airborne Contaminants during Controlled Residential Fires
NIOSH Fire Fighter Resources
NIOSH Pocket Guide to Chemical Hazards: Hydrogen Cyanide
Cardiovascular & Chemical Exposure Risks in Today’s Fire Service
================================================
Smoked Out: Are Firefighters in More Danger than Ever Before?
New construction materials are making firefighting more hazardous to
the health and well being of first responders, as well as building
tenants and homeowners.
At first glance, our towns and neighborhoods may look safer from fire hazards than they were 50 years ago. Today's homes and businesses are equipped with more advanced fire and smoke sensors, and firefighters have more durable safety equipment and a deeper knowledge of fire fighting. American cities also enforce strict fire safety codes and other building regulations to prevent fires and minimize risks when they do occur.
Yet modern buildings are burning and collapsing
faster than those that were built 60 or 100 years ago. Published studies
indicate residential fires are more difficult to escape and more likely
to have quick flashover rates, giving firefighters less time to reach
buildings and homes before disaster strikes.
How could an element as basic as fire become more dangerous? Shouldn't we have learned from our past mistakes in stopping, harnessing and preventing fires?
It turns out that one key variable has affected our ability to deal with fires: the materials that fuel them. Just as technology has increased our power to detect and fight fires, it also has introduced a variety of modern materials and construction trends that make smoke and fire more difficult to contain.
Some of these more-recent changes include flammable textiles, plastics with high burn rates and less practical building layouts and foundations. It's difficult to pinpoint just one problem; a variety of construction and manufacturing changes have converged to make recent fires hotter and the smoke from those fires more deadly.
Modern Building Materials
One of the biggest changes in city fires is the use of synthetic building materials. While walls once were thicker and lined with heavy-duty construction or insulation materials, today's thinner wall linings are easier for fires to penetrate.Windows and interior doors also are failing faster, making structures less sustainable when fire happens. According to UL tests, modern windows fail twice as quickly, while doors are failing after only five minutes of fire exposure.
UL calls our synthetic building materials a “perfect storm” of flammability and smoke risks, yet we still favor materials that burn hotter and collapse faster.
Modern homes are, overall, built of lighter materials and more synthetic materials. Thanks to structural components and support systems that trade lumber for engineered joists and other man-made parts, modern homes will likely be more vulnerable for the foreseeable future. But it's not just the construction materials that contribute to this hazard.
Modern Furniture
Plastics have risen in prominence in many industries over the past few decades, and home furnishings are no exception. The modern household is outfitted with a variety of plastics and synthetic textiles. These synthetic fabrics and linings are replacing cotton, wool and other natural materials, which are more expensive and less durable but also are slower to burn.
Plastics
have higher heat release rates, which make them more combustible and
dangerous than natural materials that have fewer fumes and lower heat
release rates. Common synthetic materials include polyurethane foam
cushions with hot burn times and deadly fumes, nylon and acrylic
upholstery that are full of combustible chemicals and appliances that
are full of gases and masses that shouldn't be combined in high-heat
situations. Together, all of these modern-day materials join forces to
set a deadly trap for unprepared tenants, residents and first
responders.New Smoke, New Dangers
Flames only are part of the problem. Since the advent of synthetic furniture and construction materials, smoke signatures have been identified with 223 percent more frequency. When synthetic materials burn, their smoke often contains dangerous chemicals that kill faster and maim more severely.When a fire breaks out, synthetic materials such as polyurethane and nylon generate a toxic cyanide gas called hydrogen cyanide that can be deadly in small doses. This toxic gas is found in all kinds of building furnishings, insulation, carpets, appliances, plastics and clothing.
Firefighter Nation estimates that hydrogen cyanide (HCN) is up to 35 percent more dangerous than carbon monoxide (CO), which suffocates the organs. Though CO can kill quickly, HCN attacks the central nervous system, disorienting people who are exposed. HCN exposure can prevent firefighters from effectively managing fires, and everyday citizens from escaping buildings. Both gases are by-products of burning synthetic materials.
What Can We Do?
Building traditions and manufacturing methods always evolve, and it's possible we can reduce our fire and smoke dangers by using less toxic synthetic materials in the future. Until then, we must adapt to the current threats and ensure that building occupants and firefighters develop strategies for controlling risks during fires.Escape faster – Homeowners and business owners should prioritize faster escape times from buildings. After a fire alarm goes off, don't wait more than 30 seconds to get out, as building materials may emit toxic smoke and deadly heat within minutes.
Fire department training programs – Fire departments increasingly are turning to new training methods and programs to educate fire departments about the new risks. For example, Fire Engineering suggests training programs that help firefighters identify the sources of cyanide, understand the physical and psychological effects of cyanide exposure and learn how to immediately treat it.
Fire safety equipment – There is one piece of fire safety equipment is instrumental in protecting people from these new threats. Though firefighters are exposed to hotter, faster and more toxic fires, they also are armed with a weapon that could save their nervous system and oxygen levels: their self-contained breathing apparatus (SCBA). Every firefighter relies on his or her SCBA to prevent breathing in smoke and toxic fumes. Researchers recommend more in-depth training to make sure firefighters know exactly how to appropriately use their SCBAs.
Fire safety will continue to evolve as we learn more about our risks and develop new strategies for avoiding them. However, if you're like most modern Americans, you're surrounded by synthetic building materials and plastics every day. It's important to rely on fire safety equipment that you know how to use, and make design choices that don't increase your risks.