The gas which produces systemic toxicity without causing local irritation is:

B i.e. Carbon Monoxide Carbon Monoxide Poisoning CO is a colourless, tasteless, non irritant gasQ which is produced due to incomplete combustion of carbon. CO poisoning is defined as > 15 % carboxyhemoglobinQ in blood (normal < 1.5 % in nonsmokers, < 10 % in smokers). Diagnosis is made by cooximetric measurements of blood not by pulse oxymeter. CO has 200 - 300 times the affinity of 02 for hemoglobin. It decreases the affinity of 02 and shifts hemoglobin dissociation curve to right. -Toxicity may be due to smoke inhalation or by degradation of desflurane by CO2 absorbent Lower levels produce systemic toxicity because of binding with cytochrome-c & myoglobin and higher levels produce toxicity due to binding with Hemoglobin leading to tissue hypoxia.