By Elizabeth Elkin and Irina Anghel

A fire at a North Carolina fertilizer plant that makes a highly flammable type of nutrient entered a fourth day, with the ongoing threat of an explosion keeping thousands of locals away from their homes.

Residents were forced to flee the area around Winston Weaver Co.’s Winston-Salem plant, which makes ammonium nitrate, after it caught fire Monday night. The fire is still too fierce to allow crews, helicopters and drones to get into the immediate vicinity, and while recent rain reduced the blaze a little, more showers risk worsening air quality.

The facility has the same type of fertilizer behind deadly past explosions, including a 2020 blast that devastated Beirut’s port. It also has a bigger stockpile than there was at a Texas plant that exploded in 2013, killing 15 people and damaging more than 150 structures across a 35-block area.

The Winston-Salem fire consumed the whole building, causing it to collapse, and about 6,000 people living within a one-mile radius of the plant were told to evacuate. Officials want it to burn through all the material and run out of fuel, fire chief Trey Mayo has said. 

The facility has about 5,000 tons of finished fertilizer and 500 tons of the chemical compound inside. It also has about 90 tons of ammonia nitrate in a rail car beside the building, according to Mayo.

“At the beginning of this incident, there was enough ammonium nitrate on hand for this to be one of the worst explosions in U.S. history,” he said.

See more: Blast feared as fire consumes North Carolina fertilizer plant

The fire department on Thursday said there’s no timeline yet for when people can return home.

Expected rain could also pose a risk to air quality. Showers push smoke down and that’s a health hazard for people with respiratory illnesses, Winston-Salem Fire Department Battalion Chief Patrick Grubbs said at a briefing on Thursday. 

The Environmental Protection Agency has put out remote monitors to transmit air-quality data in real time. They’re measuring nitrogen dioxide, compounds of sulfur and other “particulate matter,” Mayo has said.

Fertilizer market

While the U.S. fertilizer-grade ammonium nitrate market accounts for a fraction of total domestic nitrogen consumption, it comes at a tumultuous time for the market. Nutrient prices have surged to records around the world following an energy crunch that curbed production in Europe, while fertilizer supplies also face threats from export curbs and trade sanctions.

That’s adding to costs for farmers and prompting some to curb fertilizer usage, threatening to curb crop yields and further raise global food prices that are near a record high.

A representative for Winston Weaver has said that all employees are safe. Wake Forest University, which is mostly outside of the evacuation area, canceled classes for the rest of the week at some locations.

--With assistance from Allison Smith and Bruce Rolfsen.

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