The Transport Commissioner has issued a circular recalling taxis older than 15 years to the Regional Traffic Offices (RTO) for stringent fitness tests, prompting the Mumbai Taximen's Union to threaten an agitation. According to the circular, issued by Transport Commisserion vinay Mohan Lal last wednesday the three RTOs-- Mumbai Central, West and East -- have been directed to begin issuing notices to taxis more than 15 years-old and to cancel the registratin of taxis with high pollution levels and suspend those of defective taxis till they are rectified.