DAMASCUS - Days after a suspected poison gas attack killed hundreds of people in crop-growing suburbs, residents of the Syrian capital say they are afraid their food and water supplies may be contaminated.Western countries believe President Bashar Assad's forces carried out the worst chemical weapons attack since Iraqi leader Saddam Hussein gassed thousands of Kurds in 1988. Syria's government denies any role in the deaths and blames rebels.UNUSUAL FEROCITYDamascenes say the night of the poisoning, before dawn on Aug 21, saw some of the loudest and most continuous bombardment of the war."Where I live, we usually hear missile fire, and we hear it pierce the air above us, and we hear it land in a thud and explode," said a resident of Rukn al Din, where government artillery fires upon nearby Jobar, a rebel-held area in Ghouta."But on Wednesday, I swear we heard it from new angles and new places. It felt like the missiles were firing from all over the city onto Ghouta," he said.Whether Damascenes blame the government or the rebels for the poisoning generally depends on which side they support."I couldn't say who did it ... But each side speaks with the same conviction, blaming the other side. And we just want this to end. We're exhausted," said Um Hassan.Now that US President Barack Obama is considering a response, residents also have the prospect of Western military action to contend with, after two and a half years of a war that has already killed 100,000 people.Ahmad, displaced for months into Damascus from Moadamiyeh, another of the suburbs where the chemical attack took place, said he no longer "cares what happens".He now shares one room with his wife and their five children in the basement of a downtown Damascus building where he works as a superintendent."We've lost so much. We have no idea what the status of our home is. We can't reach our neighbors who still live in our street ... And you're asking me what I think about America coming? Things can't get much worse."Whoever is to blame, grandmother Hana said her three daughters were now fretting about what to feed their children."They keep calling me throughout the day, and they are frantic. They ask: 'Mum, what about the watermelon? Does it absorb the chemicals? What about the milk?' I try to calm them down, but I'm very worried myself. What if it takes years for any effects to show up in the children?" she said.The poison gas hit the Ghouta area, where acres upon acres of agricultural land supply the capital of 3 million people with fresh vegetables, meat and dairy."I hope God will protect us. Because I would really rather plant my own tomatoes and vegetables, but how will they grow in my third floor apartment? I don't even have a balcony," said Um Hassan, another grandmother.She it was the first time she was seriously worried about food contamination since the US-led invasion of neighboring Iraq made Syrians fear contamination of imported food.The Syrian authorities have yet to respond with any clarity about whether people need to take special precautions to protect themselves from possible contamination.It is not yet clear what poison or mixture of poisons were responsible for the killings.Sarin, which the United States and France believe was used in previous, smaller incidents in Syria, mixes with water. People can be exposed to it by touching or drinking contaminated water, according to the website of the US Centers for Disease Control and Prevention. People can also be exposed by eating contaminated food."Do we have to keep our windows closed? How long does the poison stay in the air? I hear different things from people," said 40-year-old man who works as a physical therapist and lives less than a 15-minute drive from one attack."Do we have to worry now about leaving the city? Are we considered contagious?" he said.