If the zombies could be distracted in such a manner, a flare might not be a horrible idea. But bear in mind that this is only for the purposes of distraction, not for killing zombies.
Of course, if you can distract them with noise and light, why not just use one of those relatively cheap personal alarm systems? Pull and throw. Continuous loud noise and a flashing light.
"I live among the cold, the false,
And I must seem like them;
And such I am, for I am false
As those I most condemn. "
L.E.L., "Lines of Life"