Firefighting
Firefighting is a dangerous profession due to the toxic environment created by combustible materials, with major risks being smoke, oxygen deficiency, elevated temperatures, poisonous atmospheres, and violent air flows.
Additional hazards include falls – a constant peril while navigating unfamiliar layouts or confined spaces amid shifting debris under limited visibility – and structural collapse that can exacerbate the problems encountered in a toxic environment.
[5] In the 3rd century B.C., an Alexandrian Greek named Ctesibius made a double force pump called a siphona.
[5] Another traditional firefighting method that survived was the bucket brigade, involving two lines of people formed between the water source and the fire.
Upon arriving at the scene, however, the firefighters did nothing while Crassus offered to buy the burning building from the distressed property owner, at a miserable price.
[7][8][9][10] Prior to the Great Fire of London in 1666, some parishes in the UK had begun to organize rudimentary firefighting crews.
Steam-powered apparatuses were first introduced in the 1850s, allowing a greater quantity of water to be directed onto a fire; in the early 1930s they were superseded by versions powered by an internal combustion engine.
Firefighting started to become formalized with rules for providing buckets, ladders, and hooks, and with the formation of volunteer companies.
Firefighters must also have, or be able to acquire, knowledge of department organizations, operations, and procedures,[5] and the district or city street system[5] they will have to negotiate in order to perform their duties.
They must meet minimum physical fitness standards and learn various firefighting duties within a reasonable period[5] Examples are: Specialized areas of operations may require subject-specific training.
[5] A chief officer must be familiar with sources of fires, including explosives, hazardous chemicals, and the combustion qualities of materials in buildings, homes, and industrial plants.
For example, the city of Houston in the United States requires every tenant in a high-rise to have at least one Fire Warden for every 7500 sq.
[20] As stated in the National Wildfire Coordinating Group's Incident Response Pocket Guide: "A safety zone is an area where a firefighter can survive without a fire shelter" and should be "...at least four times the maximum continuous flame height.
A firefighter's SCBA usually hold 30 to 45 minutes of air, depending on the size of the tank and the rate of consumption during strenuous activities.
[25] Some chemical products such as ammonium nitrate fertilizers can also explode, potentially causing physical trauma from blast or shrapnel injuries.
Sufficient heat causes human flesh to burn as fuel, or the water within to boil, leading to potentially severe medical problems.
[28] "Three hours of fighting a fire stiffens arteries and impairs cardiac function in firefighters" according to a study by Bo Fernhall, a professor in the department of kinesiology and community health in the College of Applied Health Sciences, and Gavin Horn, director of research at the Illinois Fire Service Institute.
The conditions (observed in healthy male firefighters) are "also apparent found in weightlifters and endurance athletes..."[29] Once extinguished, fire debris cleanup poses several safety and health risks for workers.
[30] Polyaromatic hydrocarbons (PAHs), some of which are carcinogenic, come from the incomplete combustion of organic materials and are often found as a result of structural and wildland fires.
Ideally, part of reconnaissance is consulting a plan for the building that provides information about structures, firefighter hazards, and in some cases the most appropriate strategies and tactics for fighting a fire in that context.
There are four elements[38] needed to start and sustain a fire and/or flame: temperature, a fuel, an oxidizing agent (oxygen), and a chemical reaction.
The resulting self-sustained chemical chain reaction is complex and requires fuel, an oxidizer, and heat energy to come together in a very specific way.
An oxidizing agent is a material or substance that will release gases, including oxygen, when the proper conditions exist.
Sound waves have been successfully used in a device fabricated by two George Mason University senior engineering students, Viet Tran and Seth Robertson, but the procedure is still awaiting a patent (2015).
As gas cools it becomes denser (Charles's law); thus, it also reduces the mobility of the smoke and avoids a "backfire" of water vapor.
If the flow is too low, the cooling is insufficient, and the steam that is produced can burn firefighters (the drop of pressure is too small and the vapor is pushed back in their direction).
Paul Grimwood introduced the concept of tactical ventilation in the 1980s to encourage a better thought-out approach to this aspect of firefighting.
Grimwood's original definition of his 1991 unified strategy stated that, "tactical ventilation is either the venting, or containment (isolation) actions by on-scene firefighters, used to take control from the outset of a fire's burning regime, in an effort to gain tactical advantage during interior structural firefighting operations."
In most cases of structural firefighting, windows are broken or removed from the outside of the building to provide efficient horizontal ventilation.
The main risk of this method is that it may accelerate the fire, or even create a flash-over; for example, if the smoke and the heat accumulate in a dead end.
