The material dropped is a product called Phos-Chek, a flame retardant.
AFP
Above the fires which are devastating part of Los Angeles, a surprising vision: planes dropping thousands of liters of a bright red or fluorescent pink substance above forests, houses and cars.
This material, which stands out starkly against this backdrop of grayish plumes and charred landscapes, is a flame retardant, essentially a product called Phos-Chek, used by the Forest Service since the 1960s.
“It’s an incredible thing… you can see it so easily,” said Jason Colquhoun, a 53-year-old pilot with HeliQwest, a helicopter company specializing in firefighting.
But since last week, the substance has been dropped over residential neighborhoods on a scale “never seen before,” notes Daniel McCurry, associate professor of civil and environmental engineering at the University of Southern California.
And so this disturbing question: is it dangerous, or not?
Phos-Chek is marketed by Perimeter Solutions, a fire protection company. It’s a mixture of ammonium phosphate, a common fertilizer, and various additives, including iron oxide (from rust), which give it its neon color.
This bright tint helps pilots ensure they don’t leave uncovered areas above fires, Colquhoun says.
Before being released, the product, which is in the form of a powder, is most often mixed with water in large basins.
AFP
Normally, when pilots drop water, they have to spot “the bright and the dark” to know where to make their next drop. But with this substance “it’s so much easier to see,” he explains.
Another advantage over water: The flame retardant continues to work even after the water it is mixed with evaporates, McCurry says.
Thickeners provide a viscosity to the product that prevents it from drifting away from the target area, adds Mr. McCurry, who has conducted research on heavy metals in this type of flame retardant.
The product, which comes in the form of a powder, is most often mixed in large basins before being loaded onto planes and helicopters for coordinated drops, Mr Colquhoun adds.
Mr. McCurry explains having seen images where “a bushfire stopped its progress exactly on the line up to which Phos-Chek had been spread”.
But he has mixed opinions about the product.
A former firefighter explained to him that the product “wasn’t of much use” in the case of high-intensity fires, like those which have killed 25 people over the past week in Los Angeles and are still out of control.
“Virtually non-toxic”
The Forest Service explains that it only uses flame retardants “that meet Environmental Protection Agency criteria ensuring that they are “virtually non-toxic” to humans, mammals and aquatic species.” .
It prohibits releases onto bodies of water and areas hosting threatened or endangered species — the exception being when “human life or public safety is threatened” and it is “reasonable to believe” that the retardant could contain the fire, he told AFP.
But accidents can happen, with a change in wind direction or an involuntary release.
An old Phos-Chek formula, LC95, which Mr. McCurry’s research showed had high levels of heavy metals that could contaminate drinking water, was withdrawn across the United States on December 31.
The one used now, MVP-Fx, is less toxic.
But it can cause skin irritation and, if ingested, cause nausea and vomiting.
McCurry says the Forest Service has lost lawsuits in the past on environmental cases, but now Phos-Chek is “probably environmentally safe.”
“At the same time, the impact on human health is not yet entirely clear,” he concedes.
“Over the past week, there have been drops on a scale never seen before,” he continues, adding that the product is most often dumped away from inhabited areas, or in smaller quantities. “But who knows?” he concludes.
Flame retardant also colors cars…
AFP
(afp)
