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Above the ruins of Los Angeles, a pink barrier faces the flames
Above the fires which are devastating part of Los Angeles, a surprising vision: planes drop thousands of liters of a bright red or fluorescent pink substance above forests, houses and cars. This material, which crudely standing out 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 a 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? – Fertilizers and rust -Phos-Chek is marketed by Perimeter Solutions, a fire protection company. It is a mixture of ammonium phosphate, a common fertilizer, and various additives, including iron oxide (from rust), which give it its fluorescent color. This bright color allows pilots to be assured that they don’t leave uncovered areas above the fires, Colquhoun said. 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 substance continues to operate even after the water with which it is mixed has evaporated, says Mr. McCurry. 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, adds Mr. Colquhoun.M. McCurry explains having seen images where “a bushfire stopped its progress exactly on the line to which Phos-Chek had been spread”. But he has a mixed opinion on 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 at least 25 people over the past week in Los Angeles. Angeles and are still out of control. – “Virtually non-toxic” – The Forest Service explains that it only uses flame retardant “that meets Environmental Protection Agency criteria ensuring that they are ‘ almost non-toxic’ to humans, mammals and aquatic species.” It prohibits releases onto bodies of water and areas harboring threatened or endangered species — the exception being when “human life or safety public are threatened” and that it is “reasonable to think” that the retardant could contain the fire, he told AFP. But accidents can occur, with a change in wind direction or an involuntary release. An old formula of Phos-Chek, LC95, which according to Mr. McCurry’s research presented high levels of heavy metals that could contaminate drinking water, was withdrawn throughout the United States on December 31. The one used now, the MVP-Fx, is less toxic. It does not contain eternal pollutants, nor substances “known to cause cancer or other ailments”, prohibited by Californian law, assured AFP Perimeter Solutions, the company that markets Phos-Chek. But it can cause skin irritation and, if swallowed, cause nausea and vomiting. McCurry explains that the Forest Service has lost lawsuits in the past on environmental cases, but that now Phos-Chek is “probably harmless to the environment.” At the same time, the impact on human health does not “It’s 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 inhabited areas, or in smaller quantities.”But who knows?”, he concludes.bur-st/hg/des/pt/ph/cyb
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