Editor's note: Early reports said the pipes stored under the bridge were made of PVC, but CNN and other outlets are reporting that the pipes are HDPE or high-density polyethylene.

There was a big fire in Atlanta on Thursday that caused a section of an elevated highway to collapse. This CNN screen capture shows the statement “the Atlanta Fire Department is working to identify the cause of the fire.” But on Reuters they note the source that's fueling the fire:

[Georgia Gov. Nathan] Deal said the fire that led to the highway collapse appeared to have been fueled by a large pile of PVC piping under the structure. Authorities did not know who owned the piping or who had put it under the bridge, Deal said.

On CNN, they report:

According to the Georgia Department of Transportation, the area beneath that section of the expressway is "a secured area containing materials such as PVC piping which is a stable, non-combustible material." Utilities use the piping to protect fiber optic and other electronic cables.

That’s interesting, because PolyVinyl Chloride (PVC) does burn, albeit not as easily as other materials. There are many different claims about PVC, which is why it has been a serious point of contention among architects for a number of years. Certifiers like the Living Building Challenge have it on their red list of prohibited materials. The Cradle to Cradle system lists it as the only “knock-out” chemical; in that system, you cannot certify a product if it contains it.

Avoid or ignore plastic He's holding a PVC pipe — and that's a contentious issue. (Photo: Rich Williams/Plastics News)

PVC was the subject of a long, drawn-out battle between the U.S. Green Building Council (which runs LEED) and the plastics industry over whether its use should be discouraged. There are a couple of reasons for this. It's manufactured with chlorine, which is highly reactive and can form persistent bioaccumulative toxic chemicals (PBTs). It's often mixed with stabilizers like lead or cadmium, both of which are toxic. But one of the bigger worries about PVC is what happens when it burns. (And not withstanding what the Georgia Department of Transportation says, it does burn.)

The Environmental Protection Agency used to have a great page of information in its toxicological review of vinyl chloride, but for some reason, that page has been taken down. According to a European document on home burning of waste by the Women Engage For a Common Future or WECF:

The most dangerous emissions can be caused by burning plastics containing organochlorine-based substances like PVC. When such plastics are burned, harmful quantities of dioxins, a group of highly toxic chemicals are emitted. Dioxins are the most toxic to the human organisms. They are carcinogenic and a hormone disruptor and persistent, and they accumulate in our body-fat and thus mothers give it directly to their babies via the placenta. Dioxins also settle on crops and in our waterways where they eventually wind up in our food, accumulate in our bodies and are passed on to our children.

BuildingGreen, one of the most reputable sources on green building in America, add its two cents in a document called Should we phase out PVC?:

Dioxins are created when PVC is burned under less-than-ideal conditions, as in building fires. Ash from fires in PVC warehouses and factories contains dioxin at levels ranging from several to several hundred parts per billion. While isolated incidents of exposure to dioxin may not be a serious health threat to fire victims, such fires can contribute to environmental contamination.

They explain the problems with dioxins, albeit for longer-term exposure:

Some of the most serious allegations against PVC stem from the increasing evidence of long-term health and environmental damage caused by persistent organo-chlorines in the environment. These substances include dioxins, furans, and polychlorinated biphenyls (PCBs). There is convincing, though not definitive, evidence linking these toxins to increased breast cancer rates in women, lower sperm counts and reproduction-related birth defects in men, and a host of ailments affecting wildlife, particularly species high on the food chain. Much of the concern is focussed on disruption of the endocrine system, because severe health effects are likely even at very low levels of exposure to the toxins.

David Maynard’s book, "Toxicology, Survival and Health Hazards of Combustion Products," has a section about dioxin from accidental fires:

book on toxicoligy Excerpt from book on toxicology (Photo: David Purser, Robert Maynard, James Wakefield)

Even the vinyl manufacturer's website, PVC.org, which goes on about how safe the stuff is, notes that it does burn. Here's a big excerpt from the industry itself — so they can't claim it's just Greenpeace and crazy TreeHuggers:

Like all other organic materials used in buildings (other plastics, wood, clothing etc.), PVC products will burn when exposed to enough heat. However, unlike these other materials PVC products are naturally self-extinguishing, i.e. if the ignition source is withdrawn they will stop burning. Because of its high chlorine content PVC products have burning characteristics, which are quite favourable, i.e. they are difficult to ignite, the heat production is comparatively low and they tend to char rather than generate flaming droplets.

But if there is a large enough fire in a building, PVC products will start to burn and will emit toxic substances like any other organic material.

That makes me feel much better. But let’s get back to the Atlanta fire.

https://youtu.be/of3K9M_VqW8

There's all this smoke, which is full of particulates and dioxin. It's falling everywhere downwind of this fire. Yet the Department of Transportation says PVC is non-combustible, which is patently and obviously wrong, and so far as I can tell, there hasn't been a single mention about the dangers of that soot.

I don't mean to be an alarmist, but there's an issue here. Burning PVC creates toxicants that are harmful and that linger in the environment, which is one of the main reasons much of the architectural profession wants to get rid of it. There are many people who believe that burning PVC is very dangerous indeed.

Is anyone discussing this?

Lloyd Alter ( @lloydalter ) writes about smart (and dumb) tech with a side of design and a dash of boomer angst.