A pulmonary nodule is a discrete opacity in the lung which may be caused by: 1  Neoplasm: benign or malignant. 2  Granuloma: tuberculosis. 3  Infection: roundish pneumonia. 4  Vascular: infarct, varix, granulomatosis with polyangiitis, rheumatoid arthritis.
1 Helium is also commonly used to pressurize and purge systems of unwanted gases. 2  It is also used in controlled atmospheres when the levels of different gases have to be kept constant. 3  It is used as a protective gas when growing silicon and germanium crystals and when producing titanium and zirconium.
Chemical poisoning -- Helium: Helium is a chemical used mainly in helium balloons, neon signs and diving gas.The gas is sometimes misused as an inhalant. Ingestion and other exposures to the chemical can cause various symptoms.hemical poisoning -- Helium: Helium is a chemical used mainly in helium balloons, neon signs and diving gas.