Statement 1 is Correct: The steel industry uses coal and coke as fuel and reducing agents; since these contain sulphur, their combustion and the sintering process release oxides of sulphur (SOx). Statement 2 is Correct: High-temperature operations in blast furnaces and heating processes cause atmospheric nitrogen to react with oxygen, leading to the formation of oxides of nitrogen (NOx). Statement 3 is Correct: Carbon monoxide (CO) is generated as a byproduct during the reduction of iron ore in the blast furnace and through the incomplete combustion of carbon-based fuels. Statement 4 is Correct: Carbon dioxide (CO2) is a major emission resulting from the chemical reduction of iron ore (coke reacting with ore) and the combustion of fossil fuels for energy production.