A friend of the two hospitalized said that on Saturday they were hanging out and catching some sun at Queen Elizabeth Gardens. They had purchased a blanket to take to a soccer game, so they might have been sitting or lying on a tiny contaminated area. Because a tiny exposure is lethal, all that grass, dirt, and concrete in that area should be removed and buried deep within the ground in some very rural area. This nerve agent never "naturally"biodegrades and becomes nonlethal.
Washing your spectacles, watch, and phone with baby wipes may remove the nerve agent, but the rubbish can and your hands are then contaminated. This is a far more scary problem than the Health Department admits.