Have the safety strands for Firefighters increased over the years?

better clothing helps but everyone wearing a mask rather than inhaling gases has reduced the incident of lung diseases, tracking contact with hazardous materials allows them to avoid incidents that have too much risk to try to directly attack the problem.
Better hoses and nozzles allows more effective firefighting, better staffing requirements means that no one free lances so command knows where everyone is and in case of a collapse they can start rescue operations instead of not knowing where the trapped people are located.
Today almost everyone has a radio so they can communicate with each other and command.
The departments have developed better tactics to protect firefighters, reduce fire loss, and save civilian lives.
Modern departments inspect and do pre fire planning so in an emergency they know where dangerous chemicals are located, and also where utility cut offs are and the type of construction so they know how to best attack the fire.
Better training has reduced the number of firefighter deaths in recent years, but this is still a very dangerous profession.

Strands? Do you mean standards?

Yes, they have. NFPA is constantly revising their standards. They keep upping the standards on protective clothing, SCBA, fire trucks, staffing, accountability, and other equipment.

Yes. They have better protective equipment. With thermal cameras they can see danger areas that were previously hidden.