Aircraft are currently deployed in the Los Angeles region to combat the wildfires that are wreaking havoc and threatening numerous neighborhoods. These aircraft are not only disbursing water but also releasing hundreds of thousands of gallons of bright pink fire retardant in an urgent attempt to halt the flames from spreading further.
Since the fires erupted last Tuesday, they have led to at least 24 fatalities, forced thousands to evacuate, and resulted in the destruction of more than 12,000 structures. The areas affected, driven by fierce Santa Ana winds, have burned approximately 62 square miles (around 160 square kilometers), as reported by Cal Fire. Firefighting agencies highlight the significance of using fire retardants, which are primarily designed for forest fires. However, questions arise regarding their composition and safety.
The application of these retardants in Los Angeles is crucial, as the flames are advancing rapidly through challenging terrains such as canyons, making it difficult for ground firefighters to access these areas, according to Cal Fire. Although fire suppressants are often effective, their utility is hampered by strong winds that can create hazardous flying conditions and might disperse the retardant before it can come into contact with the flames. Various organizations, including Cal Fire, the U.S. Forest Service, and fire departments from Los Angeles and Ventura counties, as well as the National Guard, have participated in these aerial operations.
Aerial fire suppressants typically consist of a mixture of water, ammonium phosphate — a compound similar to fertilizer — and iron oxide, which gives the retardant its distinctive color, as explained by Daniel McCurry, a civil and environmental engineering expert at the University of Southern California. The U.S. Forest Service, which has employed 13 aircraft to deploy these suppressants over the Los Angeles fires, claims that they help to deplete a fire’s oxygen and slow its burning rate by cooling and coating vegetation and other surfaces. The manufacturer of the fire retardant, Perimeter, states that the phosphate alters the decomposition process of cellulose in plants, rendering them non-flammable.
Despite being generally regarded as safe for humans, there are concerns about the environmental impact of these fire suppressants, particularly their effects on wildlife. The U.S. Forest Service restricts the use of aerial retardants over bodies of water and habitats of endangered species, unless human safety is at risk, due to potential health risks posed to aquatic life. McCurry noted that studies conducted by his team found heavy metals such as chromium and cadmium in at least one commonly used suppressor by the U.S. Forest Service. This research indicates a feasible correlation between fire retardants and increases in heavy metal levels in water sources downstream from wildfires, even if a direct link remains challenging to establish.
In defense of their product, Perimeter has stated that the research conducted by McCurry pertains to a formulation that is no longer in use and not utilized in California. They emphasize that the composition does not include heavy metals, which they argue are a natural component of ammonium phosphate fertilizers, and they maintain that their aerial suppressants undergo comprehensive testing by the USDA Forest Service, meeting all health and safety regulations.
The application of fire retardants has become critical in combating wildfires that pose significant health threats to millions, especially considering the toxic mix of fine particulate matter that can lead to respiratory and cardiovascular issues. Studies reveal that wildfire smoke has accounted for a significant portion of harmful air pollution in the western United States recently, as climate change continues to exacerbate the severity of these fires. Research also suggests that smoke from wildfires may have a more detrimental effect on brain health compared to other air pollution types, increasing the risk of dementia, according to findings from the Alzheimer’s Association.
Edward Goldberg, vice chairman of solutions at Perimeter, stated, “Using wildland fire retardant is essential for saving lives, protecting communities, and controlling the size of wildfires.” McCurry added that although further research into fire suppressants is necessary — particularly in the aftermath of the fires in Los Angeles — he recognizes their importance in emergency situations: “If a brush fire was approaching my home, I would prefer to have a substantial amount of that fire retardant applied ahead of it.”
