Days after Muscovites complained about a strong smell of sulphur wafting through the city, municipal officials have advised residents to don face masks to protect themselves…While Russia's Emergency Ministry pinned the eggy stench on a hydrogen sulphide spill, Russia's natural resources watchdog said the chemical in question was isopropyl benzene. Both agencies linked the smell to an accident at a Gazprom oil refinery in the south of Moscow, though the company later denied any such accident had taken place…[T]he German Embassy's staff doctor issued a notice to the embassy's employees…saying “independent observers suggest that industrial companies are increasingly releasing emissions.” In the doctor's statement, employees were warned to avoid going outdoors unnecessarily over the weekend.