1. The maintenance workers were reported to have violated safety operation requirements by entering the sewage cellar without wearing gas masks.
2. Chemical warfare vehicles and gas masks were sent in to deal with that contingency.
3. All the stations have also been equipped with gas masks and protective gloves for staff to handle any suspect item.
4. Demonstrators around him wore masks to protect against tear gas and showed off spent gas canisters and bullet casings.
5. So poisonous were the gas emissions that workers had to wear surgical and gas masks to protect them.