The main causes of death, as well as incapacitation in the fire, are the Asphyxiant gases. From the loss of the consciousness, the result of incapacitation is due to the combined hypoxic effects for the carbon monoxide, HCN, CO2 and by the various additional effects from the low of the oxygen hypoxia in the NO2 plus the inhaled irritants. The escape is presented by a loss of the consciousness, and it's further take up the  Asphyxiant gases a compare to the comatose result in the death of a few minutes which is unless the reused of occupants. When the effects of the different combination of the Asphyxiant gases are cause the incapacitation during the fires which are supposed the approximately additive by the number of the interactions which is considered. The tenability of the Asphyxiant gases depends on the degree of pain along with the distresses which is supposed to be constituted with the acceptable limits (D.A., 2011).

        In the Tenability of the Asphyxiant gases in the building, the main hazards for the occupants as well as the exposure for the heat are shown in the below figure 1. The assessment of the hazards occupants for the smoke, then the author gives the comprehensive review of the tangibility limits if eth exposures of the heat and the toxic gasses.

Figure 1 Exposure in Building Fire

In the tangibility of Asphyxiant gases, there is the exposure of heat may be leads the life threat;

Heat stroke

Burns or Skin Pains

Respiratory tract burns

There are some causes for the tenability of the Asphyxiant gases for heat exposure is summarized in table 1

Table 1: Tenability Limits for Exposures to Asphyxiants

Tenability criteria for Toxic Gases

        For the fire safety in the design and the building analysis, the tenability criteria must be the set for the ensures of that an occupant who is not exposed for the various conditions that may exceed the tenability limit. In the tenability criteria of the Toxic gases there are the following assumptions;

Due to the radiation as well as convection the heat exposure is the primary along with the upper limits for the skin that burns in the threshold.

A tract of the respiratory is burned occurs at the same limits for the skin burns along with the spate criterion which is needed.

During the fire, the air environment is approximately <10% of water.

        The toxic gasses like the primary Asphyxiant gases which are the CO, HCH , as well as the upper limits for the incapacitation of the threshold with the O2 concentrations (Poh & al, 2010)

Effects of Irritant Smoke on walking speed

            The evaluation of the travel time in most of the calculations in the method is supposed for the interaction among the occupants is with the fire effluent. If the Occupants are exposed to the irritant smoke then the movement speed that is reduced. By the non-irritant smoke, the walking speed is reduced, and in the proportion, the density of smoke along with the effect of the irritant smoke is increased. The time-concentration curves are the main toxic for the fire effluents which is needed for the inputs for the smoke as well as the toxic products which are under the fire conditions (PURSER, 2019). 

        Effects of the irritant gasses involve the respiratory and, sensory irritation along with the variations which are upper respiratory tract might occur in the short exposures. Then the Effects of Irritant Smoke on walking speed at the lower concentrations is not well established. Exposure for the irritant gasses which is likely the delay of evacuation at the lower concentration where the irritant is  produced in the mild effects, and it might be impaired by the speed of the individual's movement a building (Thomas & al, 2002).

References of Tenability Limits for Asphyxiant gases 

D.A., P., 2011. Fire Toxicity and Toxic Hazard Analysis. Conference: Sixth International Seminar on Fire and Explosion Hazards.

Poh, W. D. & al, e., 2010. Tenability In Building Fires:Limits And Design Criteria, s.l.: FIRE AUSTRALIA.

PURSER, D., 2019. ASET and RSET: addressing some issues in relation. FIRE SAFETY SCIENCE--PROCEEDINGS OF THE SEVENTH INTERNATIONAL SYMPOSIUM, pp. 91-102 .

Thomas, T. & al, e., 2002. A MODEL FOR ESTIMATING SUBLETHAL EFFECTS OF IRRITANT GASES ON EGRESS TIME IN HOME FIRE SCENARIOS. Proceedings: Indoor Air.