Original sentence: All these gases, except carbon dioxide, are toxic.Apart from MIC the gas cloud may have contained phosgene, hydrogen cyanide, carbon monoxide, hydrogen chloride, nitrous oxides and carbon dioxide, either produced in the storage tank or in the atmosphere.Many other symptoms and diseases are often ascribed to the gas exposure, but there is no good research supporting this.People awoken by these symptoms fled away from the plant, in the same direction as the toxic cloud.The gas cloud, composed mainly of materials more dense than air, stayed close to the ground and spread outwards through the surrounding community.The initial effects of gas exposure were coughing, vomiting, severe eye irritation and a feeling of suffocation
Edited sentence: All these gases are heavier than air, so oxygen deficiency most likely contributed to the health effects.Because of the hypothesized reactions that took place within the storage tank and in the surrounding atmosphere, it is probable that apart from MIC, phosgene, hydrogen cyanide, carbon monoxide, hydrogen chloride, nitrous oxides and carbon dioxide were present in the gas cloud.Many other symptoms and diseases are often related to the gas exposure, but there is no good research supporting this.People woke up, coughing, vomiting, with burning eyes and a feeling of suffocation.The gas cloud rolled along the ground, spreading over the sleeping shanty town.The town was invaded by health care staff and American lawyers.They fled away from the plant, in the same direction as the toxic cloud