Sir: Recent blasts in motor vehicles that have resulted in the loss of precious lives due to poor quality and uncertified CNG cylinders have compelled me to raise concern. Increased prices of petrol and diesel forced commuters in general and commercial commuters in particular to convert their vehicles to run on CNG. In order to save money, buses have installed oxygen and carbon dioxide cylinders, which are significantly cheaper but cannot withstand the pressure to sustain, hence they are potential bombs roaming around freely. Thousands of people have ben killed in CNG cylinder blasts countrywide during the last few years. The government has miserably failed to keep any checks on low quality CNG cylinders installed in vehicles, risking the lives and property of people. These sub-standard CNG cylinders, especially in public transport, have been killing people and the authorities concerned are paying no heed to this matter. The government has to immediately devise measures and take strict action to prevent such vehicles coming onto the roads. I would suggest people remove gas cylinders from their vehicles and switch to safer fuels like petrol and diesel, particularly after the sharp decrease in fuel prices. MUHAMMED ZAFIR ZIA Karachi