New Delhi: The next phase of the odd-even formula aimed at battling pollution in Delhi will be launched from April 15 to 30, and 400 ex-servicemen will be recruited to help enforce the system, it was announced on Monday. "The second phase of the odd-even formula will begin from April 15 for 15 days," Delhi's Transport Minister Gopal Rai said. He said it would be decided by April 8 if women would be exempted -- like in the first odd-even scheme from January 1 to 15. The minister said the recruitment of ex-servicemen would be completed by April 1. The route of Delhi Metro feeder bus services would be shortened to ensure better services during the fortnight when many are expected to switch over to public transport. He said school buses would not be used this time to meet public demand for more buses. Rai said the air pollution would be monitored across the National Capital Region, not just in Delhi, during the odd-even scheme.