take a leaf from South Korea- get all the underground MRT stations be equipped with gas masks and oxygen tanks, dry food ration and water supply.
Extend these preparations to underground bunkers all across the nation, currently these bunkers used as tuition centres and/or mamak stalls, easy to stock up the gears.
How to have defence ?, when air raid shelters are turned into commercial uses...in case of emergency, what do the people run to? Everything is making money & putting on a show...
Test alarm...so often...most will just ignore...