The occasional use of chemical warfare agents (CWAs) by rogue states in current conflicts provides a reminder that these hazards are a real threat. Although hazmat suits made of fully impermeable barrier materials provide an effective means of protecting against CWAs, they also inhibit evaporative cooling which can cause rapid hyperthermia. This conundrum has motivated a search for novel materials that allow water vapor but not CWA permeation. Here we show that, at least for aerosolized CWA, this can also be achieved using a highly breathable composite fabric that self-seals only when exposed to target chemicals. Our approach is based on the use of selectively superabsorbing polymer (SAP) microbeads that are dispersed on a highly breathable fabric. Many CWAs, especially nerve and blistering agents, have low vapor pressure and can only be dispersed as a "fog" from aerosolization. We show that upon contact with an example organic aerosol (o-xylene) the proposed SAP microbeads dispersed on a nylon mesh swell highly, seal pores, and inhibit passage of the microdroplets. In contrast, in normal conditions the SAP microbeads do not absorb or swell upon contact with water and provide over 10 kg m(-2) day(-1) water permeation rate that is comparable to a cotton shirt.