can you please help me with a mask

i have made a "gas bomb", that if you enter it, it gives you the poison, and blindness effect. and basically how it works is there are particles, and a block called "gas bomb agent" that is invisible, and you can walk through it. and if you collide with the block, it gives you poison and blindness.
yeah so then i made a gas mask, that cancels the poison effect and blindness effect. but it doesnt seem to work. i think its because its cancelling the effect in the same tick that is making the entity gain that effect