In most cases, for most people, outside of the relative few who are at ground zero, none of those things are strictly necessary. Hazardous materials tend to disperse below hazardous levels or fall out of the the air fairly quickly. In WW1, with thousands of tons of chemical agents used in a single attack unprotected people a few hundred meters away were often safe. People who were a few thousand meters away from the nuclear attack at Nagasaki were fairly safe.

Near ground zero in such events you might benefit greatly from an elaborate, million dollar, shelter that recreates the life support system of a space capsule. Assuming everything works exactly right it might save you. Failure of any of a hundred details could be fatal. Far more cost effective and reliable to avoid being at ground zero when the time comes. In the end some people cannot be cost-effectively saved.

One defense contractor came up with plans to build a shelter a quarter-mile underground. It was designed to survive a 50 MT nuclear blast directly on top of it. Sounded good until someone figured out that it would be covered with a layer of highly radioactive glass several hundred feet thick. That the people inside would need to stay inside for months before digging out, or hiking out over the radioactive hole, would make sense. The contractors volunteered that such issues could be accommodated. For the right amount of money of course.

The good news is that except for the unlucky small fraction of humanity too close to ground zero during a chemical, biological or nuclear event much less elaborate methods and shelters work quite well. As much as the conspiracy theorists like to say that plastic sheeting and duct tape are useless, just a way to make it easier to pick up the bodies, the fact is it works in large number of situations for anyone outside a critical distance.