Section 181(2)(c) in Bihar Board's Miscellaneous Rules, 1958
(c)The period of stay in a bad or unhealthy station should not, however, be more than 2 years at a stretch. A list of such bad or unhealthy stations in each district should be prepared, a copy of which should be sent to the Divisional Commissioner concerned and the Board for record. No change should be made in that list without the approval of the Board through the Commissioner.