The couch ignition on the British configuration was very different from the French and US configuration for all three ignition sources. Very rapid fire growth occurred for the French and US configurations at approximately 3 min into the burn with very little difference between the three ignition sources. All of the French and US configuration burns produced white smoke for a very short period of time. The transition to black smoke stated at the same time as the rapid fire growth, roughly 3 min. Ignition of the second item, the Ektorp Chair, in these room burns was concurrent with flashover at between 4 min and 5 min. The British configuration required in excess of 15 min for the fire growth rate to visibly increase. The time between 15 min to 18 min showed moderate growth and the post 18 min showing very rapid growth. At the 18 min time frame the smoke in the room transitioned from white to black. As with the French and US rooms, the second item ignited was the Ektorp chair followed immediately by the wooden coffee table. The second items ignited a few seconds prior to the transition to flashover. There was a difference in the timing of the fire growth for the British configuration room burns based on the ignition source.
Heat Release Rate Data
Two different sets of comparisons were performed on smoke and heat release data. The order of events for each country configuration was similar for the timing of flashover and relative intensity of pHHR for each of the three ignition sources. The oxygen consumption calorimetry measurement of HRR rose more slowly for the British configuration compared to both the US and French configurations for all three ignition sources. The measured values of HRR show a minimum of a 15 min delay for the British configurations as seen in Figures 4, 5, and 6. The three configurations versus the ignition size used are shown in separate graphs with: Figure 4 being the crib 4, Figure 5 being the crib 5 and Figure 6 being the crib 6. To interpret these graphs, the − 2 min start time represents the baseline measurements for each test till time zero. All ignition sources were ignited at time zero. Peak heat release rate (PHRR) was highest for the French configuration with crib 5 producing 3.3 MW at 5.9 min. Overall, the US and French configurations were very similar for each ignition source with the largest ignition source, crib 6, resulting in the lowest pHRR. The crib 5 ignition source did show the same timing for the rapid rise of HRR for the US and French rooms but the pHRR was 400 kW higher for the French room. The British configuration produced a pHRR 320 kW larger for crib 5 than crib 6. The data appear to indicate that the crib 5 ignition source may be a more severe exposure than crib 6 based on both the time to flashover and the intensity of pHRR. Another important observation is that any fire protection present in the French and US configurations is overcome by a 125 W ignition source resulting in flashover in 4 to 5 min. Also noted is that the British furniture failed to meet the standards set in BS 5852. Cribs 4, 5 and 6 caused the couch to achieve progressive burning and the room to reach flashover. According to BS 5852, the British couch was supposed to resist progressive burning for crib 5. The British couches failed this standard for both cribs 4 and 5. However, the time delay to reach flashover of 22.5 min does increase the escape time. The wood cribs used were compliant with specification in Section 9.3 of BS 5852-2006.
Examining the HRR data for the British configuration room burns, it appears that the crib 5 used in the test labeled GB-2 in Figure 7 shows a faster ignition and fire growth than for the crib 6 used in GB-3. This phenomenon was also noted in the US configured rooms but the differences were much smaller and the plots are nearly identical. The French configured rooms, however, did not follow this order but again were almost indistinguishable and nearly overlaid each other. The US and French configuration rooms showed little to no sensitivity to the ignition source size. The British couch showed a clear difference in ignition behavior with the different ignition sources with the order of crib 5 and 6 reversed. This may be due to the vertical design of crib 5 and wider design of crib 6. The energy of crib 5 is applied to a narrow vertical column possibly leading to faster breaching of the cover and access to the foam filling in the cushion and greater convective flow fire spread.
Table 3 summarizes the heat release and smoke data for all 9 of the tests. The pHRR data were very repeatable for each country and significantly different from country to country. Even though progressive ignition sources were used, the pHHR variability between tests of the same configuration was between 2.0% and 8.0% relative standard deviation (%RSD). The total heat for all configurations and ignition sources ranged from 1800 MJ to 2300 MJ with variabilities for each country configuration of 0.4% to 9.2% RSD.
Smoke Generation Data
The total smoke produced for the most fire resistant configuration, the British, was approximately half of that seen for the US and French which were nearly identical. Smoke was measured as opacity in m2/sec integrated overtime to give unit of m2. The smoke data mimic the results of the heat release rate. Figures 8, 9 and 10 show the comparison of the three country configurations for each crib source. The overall smoke production in the French and US rooms was so high that it overwhelmed the hood draft for the calorimeter and filled the entire 300 m3 laboratory in under 8 min creating near zero visibility (see Figure 11). The British room required between 20 min and 30 min to achieve the same level of smoke in the laboratory. The total smoke measurement was not affected by the smoke escaping the ventilation hood because all of the smoke was eventually vented through the hood as shown by the long tails in each of the smoke plots in Figures 8, 9 and 10. However the total smoke measured for French and US configurations was twice that measures for the British configuration, as shown in Table 3. The step like function seen for the US and French rooms in Figures 8, 9, and 10 was caused by over ranging of the smoke detector and is an artifact of the software. The drop in the smoke data for the British room in Figure 8 is a real event. The room was observed to be opaque from 22 min to 23 min then burned clear from between 23 min and 25 min. The smoke then transitioned back to opaque.
All of the rooms initially produced white smoke as shown in Figure 12 but transitioned to dense black smoke shown in Figure 11. Transition to black smoke occurred prior to reaching flashover as the oxygen level in the room dropped coincident to the higher heat release rate. Figure 12 also shows the exact location of all of the sample collection points and the thermocouple tree. The white smoke is difficult to see in Figure 12 if viewed in black and white but clearly visible in color. The white smoke is stratified approximately 0.5 m above the top of the couch.
Chemical Composition of Smoke
The chemical composition of the smoke varied widely with the phase of the fire. FTIR data were acquired for all 9 of the room burns. Data were acquired for 2 min prior to ignition to provide a pre-testing background. At the 2 min mark of each series collection, the room was ignited resulting in an immediate detection of carbon dioxide (CO2), confirming that the system was functioning properly. There was an approximate 20 s delay from sample collection to the read out on the spectrometer due to the length of the sampling line and volume of the 2 m gas cell. The time delay and the 2 min baseline are already subtracted in the time data shown in Table 4. Summary of the FTIR data is shown in Table 4 for the crib 4 burns of each configuration. The FTIR data for the remaining crib tests is very similar and can be found in the supplemental materials.
All of the rooms produced hydrogen cyanide (HCN) which has an immediately dangerous to life and health (IDLH) value of 50 ppm  and was detected at the door but not in the center of the room. The room center is measured at a height of 0.457 m from the floor below the smoke layer which may account for this difference. The British configuration produced a peak of 1030 ppm at 21 min 6 s; this was the lowest concentration of HCN collected in any of the three room configurations. The French configuration produced 1230 ppm at 6 min 6 s and the US room produced 1600 ppm at 6 min. Another interesting result was that sulfur dioxide (SO2) which has an IDLH of 100 ppm  was produced in all 9 room burns and was detectable in the center of the room and at the doorway. The detection of SO2 occurred after the foam of the furniture had been consumed and the wooden composition of furniture was the primary fuel. Ammonia (NH3) which has an IDLH of 300 ppm, was only detected in the French and US room burns at the doorway with values of 2500 and 2740 ppm, respectively. Ammonia detection also occurred after transition to flashover.
Figure 13 shows the full spectrum of the French configuration FR-1 room burn measured at 1.52 m height in the doorway. In the spectra, HCN and carbon monoxide (CO) were clearly visible at high concentration. This is the gas measurement at approximately 1 min after flashover or 6.5 min after ignition of the crib 4. CO2 and water represent the majority of the peaks; however, chain scission fragments of the polymers were present with the ethylene (C2H4) and methane (CH4) peaks. Ammonia (NH3) was also seen around the ethylene peak between 900 cm−1 and 1000 cm−1. Figure 14 shows the only detection of hydrogen chloride (HCl) as well as detection of SO2 in a room burn, occurring at 30 min into the GB-1 room burn. The high concentration of HCl indicated earlier in the trace was due to interference from the ethylene peak. Only the smaller peaks at time 32.9 and 35.4 min were authenticated as HCl by manual examination of each spectra in the series. Corrected for the elevated baseline, the concentration in both cases was approximately 65 ppm for HCl which is near its IDLH value of 50 ppm . Hydrogen Bromide (HBr) was not detected in any of the room burns.
Also in Figure 14 is the confirmation of SO2 in the spectra with resonances centered on 2500 cm−1. The main resonances for SO2 are found between 1300 cm−1 and 1400 cm−1, but these peaks were often buried in the water peaks and other organic molecules making quantitation in that region more difficult.
The 22 min run up to the flashover for the GB-1 burns produced very little or no narcotic gases such as CO and HCN. At 22 min into the burn, shown as approximately 24 min on the time scale in Figure 14, high concentrations of CO, HCN and organic vapors were detected at the doorway. Conversely, the burns of both the French and US configurations produced these toxic emissions very early in the fire. High levels of HCN (1234 ppm and 1600 ppm) and CO (28,000 ppm and 38,200 ppm) were detected between 6 min and 8 min at the doorway of the burn room. Comparison of the gas concentration plots in the top pane of Figures 13 and 14 show the significant time difference for fire gas production. There is a shift from 3 min to 23 min between the French and the British configurations.
For the VOC collection and analysis, the British configuration rooms had a sufficient period of white smoke, 17 min or longer, to ensure that the samples were clearly separated white from black. The French and US rooms had less than 3 min where white smoke was produced followed by rapid transition to black smoke and flashover. For the shorter duration white smoke periods some of the transition to black smoke may have been trapped in the white smoke samples. Of the 65 compounds that are calibrated for the VOC analysis, 24 were detected in at least one of the 18 samples collected. After conversion to black smoke, the number of analytes and their concentrations of analytes increased significantly. Chlorinated hydrocarbons were detected in all room configurations and all tests. However, only the British configurations produced 1, 2-dichloro-propane, a decomposition product associated with some phosphorus containing fire retardants.
Acrolein was detected in both white and black smoke above acutely toxic levels. Levels increase 10 fold when transition to black smoke occurred. The highest detected concentration of acrolein was detected post-flashover in the US room configuration. Benzene was also present in the white smoke at about 1 ppm; however, the black smoke contained 20 to 50× that of the white smoke. The OSHA Short Term exposure limit is 5 ppm for Benzene . The highest values of benzene where found post-flashover in the French configured rooms in Test FR-1 at 50 ppm with a limit of quantification (LOQ) of 0.001 ppm.
In conjunction with the VOC analysis, a list of tentatively identified compounds (TIC) was generated with approximate concentrations. Allyl chloride was detected in two of the samples for the British rooms at about 100 ppb, ST equals 2 ppm . This may indicate the presence of one of the tris-chloropropyl-phosphonate FRs. Most of the chemicals detected were monomers and break down product of poly-isocyanate foams or acrylonitrile–butadiene–styrene polymers (ABS). The highest detected TICs were siloxanes with small quantities detected in the British room configurations but up to 41,000 ppb were detected post-flashover in the French furnished rooms. The most likely source of the siloxanes was the 55 inch flat panel televisions in the room . The VOC data can be found in the supplemental information.
Semi-volatile organic compounds (SVOC) were collected for the total fire for burns GB-1, FR-1 and US-1 where XAD cartridges were collected at 3.376 Pa*m3/s over the duration of the tests. For the second and third burn of each configuration, two XAD cartridges were collected pre and post flashover. The first cartridge for the period of white smoke was initiated with the start of the FTIR collection and terminated at the transition to black smoke. The second cartridge was initiated at the point of heavy black smoke emission. Some carryover, especially in the FR2 and FR3 rooms, may have occurred because the transition time. Table 5 summarizes the data produced in the tests where white and black smoke where measured separately. The only chemicals included in Table 5 are those detected in at least one of the samples in each country configuration. Samples were measured in micrograms of material captured on the cartridge and converted to concentrations by using flow rate and time of collection. The British configuration rooms (GB-2 and 3) had fewer types of PAH, at lower concentration, and of lower molecular weight for both white and black smoke. The US and French rooms contained higher molecular weight and greater toxicity PAH at orders of magnitude higher concentration. The PAH shown in Table 5 are italicized.
The white smoke contains considerably less SVOC than the black smoke with the exception of the French rooms. The French rooms transitioned to black smoke very quickly and some of the black smoke was collected on the white smoke XAD collector for Experiment FR-3. The lower production of high molecular weight PAH in fire retardant protected materials was first reported by Blomqvist  and is consistent with the data obtained in these experiments. In addition to the standard SVOC chemicals analyzed on the XAD cartridges, these were also analyzed for TICs. The chemicals detected are similar to those detected in the VOC and VOC TIC analysis. All of the SVOC and TIC data is provided in the supplemental materials.
Chlorinated dioxins and furans were also collected using XAD collectors from the same sample lines used to collect SVOC. Table 6 lists only those chlorinated dioxins and furans detected during the respective room burns. All other values were below the limit of detection. Of the concentrations that were detected, however, all were below the level of quantitation. All three of the French configured rooms produced chlorinated dioxins. One out of three British burns produced a chlorinated furan. The one detection for the British room occurred in the black smoke collected after the transition to flashover.
The detection in the white smoke may have been caused by some of the black smoke being captured as a result of the very rapid transition from white to black smoke in these rooms. Brominated dioxins and furans were also measured for all burns. Very low levels of brominated dioxins and furans were detected during all 9 tests. All of the detections are below the level of quantitation except for the GB-2 Black smoke sample which had 1,2,3,4,6,7,8-HpBDF at 15.96 pg. Table 7 shows only those tests where the brominated dioxins and furans were measured. All other values were non-detect. All of the Chlorinated and brominated dioxin and furan data is available in the supplemental materials.
The concentration and variety of chemical components of smoke was higher in the French and US rooms then the British rooms. This is evident in Table 4 for the narcotic gases HCN and CO collected in the doorway. The PAHs in Table 5 show higher concentrations for the higher molecular weight and more chronically toxic compounds like benzo[a]pyrene and chrysene for the French and US rooms. Both the chlorinated and brominated dioxins and furans were very low across the board with no significant levels detected. The measured values for all black smoke far exceed those detected in white smoke. As a result the French and US configuration, which produced almost twice the quantity of total smoke, produced the highest quantities of toxic components much earlier in the combustion process. The concentration data by themselves, however, do not enable prediction of toxicity to humans. Synergistic, additive, and/or antagonistic effects make prediction of toxicity highly uncertain without actual toxicity testing.