Hydrogen fluoride and hydrogen chloride, but not hydrogen bromide, are subject to the European Waste Incineration Directive, which puts strict limits on emissions to air.
They are acidic gases primarily released to air from combustion of fuels which contain trace amounts of fluoride, chloride or bromide. They are highly corrosive, and inhalation of air containing low levels of hydrogen chloride can cause throat irritation or asthma. Exposure to higher levels may result in effects including rapid breathing, blue colouring of the skin, fluid accumulation in the lungs and in extreme cases severe swelling of the throat, suffocation and death. Inhalation of air containing hydrogen fluoride can cause irritation of the eyes, nose and throat. Exposure to high levels may cause muscle spasms and can damage the lungs and heart and in extreme cases can result in death.