The sale comes hot on the heels of the FTSE 100 group dumping its battery division last month, a surprise move which sent its share price spinning to a 12-month low.
The company expects to receive £150 million in cash on completion of the complex deal with New York healthcare investor Altaris.
It will retain a 30% equity stake with another £50 million payment based on performance targets but expects to take a £200 million hit from the deal.
The disposal is part of a back-to-basics strategy being pursued by outgoing CEO Robert MacLeod as he prepares to hand the reins to Bayer's Liam Condon.
Sales from its core operations, notably catalytic convertors, were up 21% to £1.9billion in the first half.
Analysts have cautioned that while that market will not disappear overnight, the clock is ticking as the world shifts to electric vehicles.
MacLeod said: "While Health has good long-term prospects, near term trading has been challenging, and the business requires significant capital investment. Health operates in different markets from the rest of JM, and we believe Altaris is the best partner to drive its future value."
He said the company would be doubling down on investment in renewables and green technology: earlier this month its 100% drop-in sustainable aviation fuel was used for the first time in a commercial flight by United Airlines.
Altaris MD George Aitken-Davies added: "We believe that our healthcare focus and experience in the pharmaceuticals sector will enable Altaris to be a good owner for Health going forward."
Matt Britzman, at Hargreaves Lansdown, said: "A new CEO at the helm, with a cash hoard at his disposal, means the group can pounce on new opportunities. But as it has proven already, it’s not easy to embark on a new business and for the moment at least, the group looks out of ideas."
Shares which have fallen by a third since November, were flat at 2004p today.