A pilot study on DTC's CNG buses conducted by a team of Manesar-based experts and submitted to Delhi Transport Minister Haroon Yusuf is to be forwarded by the Ministry to the State Transport Authority and DTC for implementation. The study has raised the issue of unchecked pollution and leakages by CNG buses. According to the team, if the catalytic converter installed in CNG buses is not replaced every 80,000 to 1,00,000 km, gases including carbon monoxide, nitrogen oxide and unburnt carbon will be released instead of being burnt in the exhaust, causing health hazards. The study conducted has also dealt with the issues of the increased life of vehicles, saving of fuel and safety of commuters.