 
 <prompt> Wetin dey prevent contamination? Based on di last question, write one context wey contain di answer. E fit be 1 - 20 sentences. Context: <response>: In recent times, dem dey use hydrogen either alone or mix am with nitrogen (wey dem sometimes dey call forming gas) as tracer gas for detecting small leaks. Dem dey use am for automotive, chemical, power generation, aerospace, and telecommunications industries. Hydrogen dey authorized as food additive (E 949) wey dey allow make dem test for leaks for food packages and e get anti-oxidizing properties. 