Nerve agents and substances causing injury to the skin and tissue are easily soluble in, and penetrate many different types of material, which renders decontamination more difficult. If chemical warfare (CW) agents have penetrated sufficiently deep, then toxic gases can be released from the material for long periods.
To be a jockey, there are no height limits, only weight limits. A rider can be of any height if they can still make weight, but it is still generally limited to fairly short individuals because of the limits on a person's body. Jockeys typically range from 5' to 5'7 in height. No need to lose any weight.
A pony cant become a horse because a pony will only grow under 14.3 hh but a colt/filly becomes a horse when it is over 14.3 hh (a colt is a male horse under the age of four and they stop growing around 4 and a filly is a female horse under the age of 4)