The correct answer is D. 1, 2, 3 and 4.
The steel industry is a major source of air pollution, releasing a variety of pollutants, including oxides of sulfur, oxides of nitrogen, carbon monoxide, and carbon dioxide. These pollutants can cause a variety of health problems, including respiratory problems, heart disease, and cancer.
Oxides of sulfur are released when sulfur-containing fuels, such as coal and oil, are
burned. These pollutants can cause acid rain, which can damage forests, lakes, and other ecosystems.Oxides of nitrogen are also released when sulfur-containing fuels are burned. These pollutants can contribute to smog and ground-level ozone, which can cause respiratory problems.
Carbon monoxide is a colorless, odorless gas that is released when fuels are burned incompletely. This pollutant can cause asphyxiation, especially in enclosed spaces.
Carbon dioxide is a greenhouse gas that contributes to climate change.
The steel industry is working to reduce its emissions of air pollutants. However, these emissions continue to be a major source of air pollution.