This Tuesday, a fire was reported in a pepper nursery in Bergschenhoek, Netherlands. However, it turned out not to be a fire, but a barrel of formic acid that exploded. The yellow smoke originated exactly from that.
Around 12.30, employees of the pepper nursery heard a loud blast coming from somewhere near the boiler room. There was also yellow smoke. The company was evacuated immediately and all employees safely left the greenhouse.
It turned out to be an explosion of a formic acid barrel. The greenhouse was kept closed to prevent spreading the smoke, as reported by the Veiligheidsregio Rotterdam-Rijnmond (Government organisation). Drones were used to see whether smoke was coming from the greenhouse. 
The concentration of the substance quickly lowered to a level in what it no longer caused irritations and the greenhouse could be ventilated safely. The cause of the explosion is still unknown.
Things went back to normal at the nursery, and the farming continued as usual. "There is a very small section close to the boiler house where the plants burnt, thus leaving marks on the leaves. This thing aside, everything goes on and we want say thank you to the emergency services for their sudden reaction", they report.
Source photos: SPA