WEBVTT 00:00:00.000 --> 00:00:02.080 Imagine for a second that you're standing outside 00:00:02.080 --> 00:00:05.839 and you catch that really distinct kind of nostalgic 00:00:05.839 --> 00:00:08.800 smell of freshly cut grass on a warm breeze. 00:00:09.039 --> 00:00:10.580 Or maybe you're just standing in your kitchen 00:00:10.580 --> 00:00:12.580 and you get that heavy, really sweet scent of 00:00:12.580 --> 00:00:15.259 a rotting banana peel on the trash. Exactly. 00:00:16.019 --> 00:00:18.079 Now, I want you to imagine that this very scent, 00:00:18.440 --> 00:00:21.399 that exact pleasant smell, is actually an invisible 00:00:21.399 --> 00:00:24.420 chemical. And not just any chemical, but one 00:00:24.420 --> 00:00:28.379 responsible for roughly 85 ,000 deaths in the 00:00:28.379 --> 00:00:30.960 muddy trenches of World War I. Yeah, it's an 00:00:30.960 --> 00:00:33.439 incredibly jarring thought. But the duality here, 00:00:33.460 --> 00:00:37.200 the irony is just striking because that exact 00:00:37.200 --> 00:00:40.259 same deadly chemical is fundamentally responsible 00:00:40.259 --> 00:00:42.619 for the polyurethane mattress you probably sleep 00:00:42.619 --> 00:00:45.179 on every single night. It's in the insulation 00:00:45.179 --> 00:00:47.560 inside your walls, and it's essential for making 00:00:47.560 --> 00:00:50.100 the durable plastics inside the phone or laptop 00:00:50.100 --> 00:00:52.140 you might be using right now. Right. You are 00:00:52.140 --> 00:00:54.659 looking at Well, basically one of the most lethal 00:00:54.659 --> 00:00:57.500 gases in human history. But simultaneously, it 00:00:57.500 --> 00:01:00.240 serves as this completely indispensable building 00:01:00.240 --> 00:01:02.840 block of modern industrial manufacturing. That's 00:01:02.840 --> 00:01:05.540 right. It really is. The story of this compound 00:01:05.540 --> 00:01:08.640 perfectly illustrates the profound double edged 00:01:08.640 --> 00:01:11.359 sword of chemical innovation. It kind of forces 00:01:11.359 --> 00:01:14.780 us to examine how humanity harnesses immense, 00:01:15.299 --> 00:01:18.159 almost incomprehensible danger just to create 00:01:18.159 --> 00:01:20.680 everyday convenience for you and me. So welcome 00:01:20.680 --> 00:01:23.200 to today's deep dive. Our mission today is to 00:01:23.200 --> 00:01:25.959 thoroughly explore this staggering duality. We're 00:01:25.959 --> 00:01:28.980 basing our entire conversation today on a really 00:01:28.980 --> 00:01:31.500 comprehensive Wikipedia article about a chemical 00:01:31.500 --> 00:01:34.209 compound called phosgene. chemically known as 00:01:34.209 --> 00:01:37.810 carbonyl dichloride or TOCl2. Right, TOCl2. And 00:01:37.810 --> 00:01:40.530 to navigate this massive stack of research, I 00:01:40.530 --> 00:01:42.810 am joined by our expert guide, who is going to 00:01:42.810 --> 00:01:44.849 help us understand the mechanics, the dark history, 00:01:45.030 --> 00:01:47.269 and the modern applications of this genuinely 00:01:47.269 --> 00:01:49.430 fascinating substance. I'm really glad to be 00:01:49.430 --> 00:01:51.269 here. The foundational text we're using provides 00:01:51.269 --> 00:01:53.870 a very thorough look at both the toxicological 00:01:53.870 --> 00:01:56.790 mechanisms and the massive industrial scale of 00:01:56.790 --> 00:01:58.930 phosgene. We have a lot of complex chemistry 00:01:58.930 --> 00:02:01.209 and historical data to synthesize today. We do. 00:02:01.390 --> 00:02:03.409 So, okay, let's unpack this. The physical properties 00:02:03.409 --> 00:02:05.629 of phosgene present a very unique set of challenges 00:02:05.629 --> 00:02:07.810 right off the bat. We were talking about a colorless 00:02:07.810 --> 00:02:11.009 gas, right? Completely invisible. And at low 00:02:11.009 --> 00:02:13.949 concentrations, it possesses this deceptively 00:02:13.949 --> 00:02:16.789 pleasant odor. The source material actually describes 00:02:16.789 --> 00:02:20.229 it as smelling like musty hay or green corn or, 00:02:20.229 --> 00:02:22.949 as we mentioned, those sweet banana peels. Yeah, 00:02:22.990 --> 00:02:25.150 that's the insidious part. Right, because the 00:02:25.150 --> 00:02:28.629 odor detection threshold The actual point at 00:02:28.629 --> 00:02:31.289 which a human nose can physically perceive that 00:02:31.289 --> 00:02:35.129 scent is 0 .4 parts per million. And that ratio, 00:02:35.289 --> 00:02:37.750 the ratio between detection and actual danger, 00:02:37.949 --> 00:02:40.430 is where the fundamental problem lies with phosgene. 00:02:40.590 --> 00:02:42.789 How so? Well, the recommended exposure limit 00:02:42.789 --> 00:02:45.330 for a human being is only 0 .1 parts per million. 00:02:45.509 --> 00:02:48.289 Oh, wow. Yeah. So by the time your olfactor receptors 00:02:48.289 --> 00:02:50.750 actually register that pleasant, freshly mown 00:02:50.750 --> 00:02:53.270 hay scent, your immediate environment already 00:02:53.270 --> 00:02:55.750 contains four times the safe limit of the gas. 00:02:55.830 --> 00:02:57.909 So your body's warning system is essentially 00:02:57.909 --> 00:03:00.449 useless. Exactly. You are relying on a natural 00:03:00.449 --> 00:03:03.370 warning system that triggers far, far too late. 00:03:03.310 --> 00:03:05.969 So how does the gas actually operate biologically 00:03:05.969 --> 00:03:08.189 once it enters the respiratory system? Because 00:03:08.189 --> 00:03:10.610 the literature heavily emphasizes that it is 00:03:10.610 --> 00:03:13.289 an insidious poison that targets the pulmonary 00:03:13.289 --> 00:03:16.250 alveoli. What's fascinating here is the specific 00:03:16.250 --> 00:03:19.389 mechanism of the chemical attack. When inhaled, 00:03:19.650 --> 00:03:22.150 phosgene travels deep into the lungs down to 00:03:22.150 --> 00:03:24.449 the alveoli. And those are the critical sites 00:03:24.449 --> 00:03:27.270 where oxygen actually transfers into your bloodstream. 00:03:27.349 --> 00:03:30.250 A gas exchange area. Right. And phosgene is highly 00:03:30.250 --> 00:03:33.150 reactive. So rather than simply irritating the 00:03:33.150 --> 00:03:36.090 tissue like smoke or dust mite, it literally 00:03:36.090 --> 00:03:38.689 chemically rewrites the architecture of your 00:03:38.689 --> 00:03:41.009 cells. That sounds terrifying. How does it do 00:03:41.009 --> 00:03:44.080 that? It targets specific protein groups, specifically 00:03:44.080 --> 00:03:48.360 the NHH, NH2, and NHH groups in the tissue. It 00:03:48.360 --> 00:03:50.800 forces them to bond with it, converting them 00:03:50.800 --> 00:03:53.680 into ester, amide, and thioester functional groups. 00:03:53.900 --> 00:03:56.280 So it essentially remodels the structural proteins 00:03:56.280 --> 00:03:58.620 of the lungs so they literally can no longer 00:03:58.620 --> 00:04:00.840 maintain their natural biological function. That 00:04:00.840 --> 00:04:03.159 is exactly what happens. The breakdown of that 00:04:03.159 --> 00:04:05.240 structural integrity completely destroys the 00:04:05.240 --> 00:04:07.280 blood air barrier in the lungs. And once that 00:04:07.280 --> 00:04:09.780 barrier is gone? When that barrier fails, fluid 00:04:09.780 --> 00:04:12.180 from your own body rapidly leaks into the lungs. 00:04:12.500 --> 00:04:15.319 This results in severe pulmonary edema. Basically 00:04:15.319 --> 00:04:18.060 drowning. Yes, the biological mechanics ultimately 00:04:18.060 --> 00:04:20.420 result in the victim drowning in their own bodily 00:04:20.420 --> 00:04:23.500 fluids. The research notes that there is a very 00:04:23.500 --> 00:04:26.930 specific formula for the danger here. Meaning, 00:04:27.329 --> 00:04:29.790 the extent of the damage doesn't solely depend 00:04:29.790 --> 00:04:32.509 on someone getting hit with a massive, highly 00:04:32.509 --> 00:04:35.829 concentrated blast of the gas. How does time 00:04:35.829 --> 00:04:38.769 factor into this toxicological equation if the 00:04:38.769 --> 00:04:41.810 concentration is extremely low? The toxicological 00:04:41.810 --> 00:04:44.910 math relies heavily on two variables. The text 00:04:44.910 --> 00:04:47.329 states that the extent of the damage is equal 00:04:47.329 --> 00:04:50.610 to the dose, and the dose is calculated by multiplying 00:04:50.610 --> 00:04:52.829 the concentration of the gas by the duration 00:04:52.829 --> 00:04:55.629 of the exposure. So low and slow is just as bad. 00:04:56.199 --> 00:04:59.540 Precisely. A very low concentration inhaled over 00:04:59.540 --> 00:05:02.040 a prolonged period can be just as devastating 00:05:02.040 --> 00:05:04.480 as a brief high -concentration exposure. And 00:05:04.480 --> 00:05:06.100 the symptoms are notably delayed, which makes 00:05:06.100 --> 00:05:08.180 it even worse. A person might catch a faint whiff 00:05:08.180 --> 00:05:10.920 of sweet corn, feel entirely unaffected, and 00:05:10.920 --> 00:05:13.079 just go about their normal day. Yes. The severe 00:05:13.079 --> 00:05:15.439 pulmonary edema might not manifest for up to 00:05:15.439 --> 00:05:18.160 24 hours. 24 hours. They feel totally fine until 00:05:18.160 --> 00:05:20.000 the physiological damage has passed the point 00:05:20.000 --> 00:05:22.720 of medical intervention. That delayed onset is 00:05:22.720 --> 00:05:26.040 a hallmark of an insidious poison. It is also 00:05:26.040 --> 00:05:28.620 exactly why modern industry workers who operate 00:05:28.620 --> 00:05:31.339 near phosgene infrastructure absolutely cannot 00:05:31.339 --> 00:05:33.339 rely on their own senses. Right. They can't wait 00:05:33.339 --> 00:05:36.639 to smell the hay. Exactly. The text details the 00:05:36.639 --> 00:05:40.199 use of special indicator badges. Workers wear 00:05:40.199 --> 00:05:42.100 these badges clipped close to their nose and 00:05:42.100 --> 00:05:44.480 mouth. What do the badges do? They continuously 00:05:44.480 --> 00:05:47.079 monitor the approximate inhaled dose in real 00:05:47.079 --> 00:05:50.079 time. If the chemical threshold is breached even 00:05:50.079 --> 00:05:53.379 slightly, the worker can seek immediate precautionary 00:05:53.379 --> 00:05:56.199 medical treatment long before any physical symptoms 00:05:56.199 --> 00:05:59.339 arise. Because even continuous low -level exposure 00:05:59.339 --> 00:06:02.240 entirely below that acute emergency threshold 00:06:02.519 --> 00:06:04.600 presents a massive problem for professionals 00:06:04.600 --> 00:06:07.139 in this field. It does. It causes chronic damage. 00:06:07.259 --> 00:06:09.259 The article mentions Leonidas Zervas, who was 00:06:09.259 --> 00:06:11.819 a prominent synthetic chemist. He worked extensively 00:06:11.819 --> 00:06:14.300 with his compound in the lab. And like a lot 00:06:14.300 --> 00:06:17.139 of chemists of his era, he experienced severe 00:06:17.139 --> 00:06:19.920 chronic respiratory health issues. Yes. He eventually 00:06:19.920 --> 00:06:22.459 succumbed to respiratory failure. And that was 00:06:22.459 --> 00:06:25.279 caused directly by the cumulative low level exposure 00:06:25.279 --> 00:06:28.420 over his entire career. It really serves as a 00:06:28.420 --> 00:06:30.800 stark metric for the long term degradation of 00:06:30.800 --> 00:06:34.180 pulmonary function. The absence of an acute edema 00:06:34.180 --> 00:06:36.639 event definitely does not equate to an absence 00:06:36.639 --> 00:06:38.980 of cellular damage. Not at all. The damage is 00:06:38.980 --> 00:06:41.639 cumulative. I want to transition to the historical 00:06:41.639 --> 00:06:44.100 synthesis of this compound because the origin 00:06:44.100 --> 00:06:46.779 is surprisingly simple compared to how complex 00:06:46.779 --> 00:06:50.240 its effects are. It was synthesized back in 1812 00:06:50.240 --> 00:06:52.899 by a Cornish chemist named John Davy. And his 00:06:52.899 --> 00:06:54.779 method was remarkably straightforward. Yeah, 00:06:54.779 --> 00:06:57.180 he achieved this by simply exposing a mixture 00:06:57.180 --> 00:07:00.500 of carbon monoxide and chlorine gas to sunlight. 00:07:00.649 --> 00:07:02.730 Just sunlight. The ultraviolet energy from the 00:07:02.730 --> 00:07:05.149 sun provided the necessary catalyst to bond the 00:07:05.149 --> 00:07:07.370 carbon monoxide and the chlorine gas together. 00:07:07.730 --> 00:07:09.649 The nomenclature he chose is actually quite poetic. 00:07:09.870 --> 00:07:12.449 He derived it from Greek. So you have phos, meaning 00:07:12.449 --> 00:07:15.269 light, and geneal, meaning to give birth. Formed 00:07:15.269 --> 00:07:17.509 by light. Exactly. Phos gene translates to formed 00:07:17.509 --> 00:07:20.689 by light. Yet this 19th century discovery, which 00:07:20.689 --> 00:07:22.930 initially just found purpose in the dye manufacturing 00:07:22.930 --> 00:07:25.389 industry, has scaled to an almost incomprehensible 00:07:25.389 --> 00:07:28.920 volume today. In 1989 alone, world production 00:07:28.920 --> 00:07:32.019 of phosgene was estimated at 2 .74 million tons. 00:07:32.360 --> 00:07:34.819 The modern world is architecturally dependent 00:07:34.819 --> 00:07:36.920 on that immense volume. Where's it all going? 00:07:37.220 --> 00:07:40.899 Of that global production, roughly 75 to 80 % 00:07:40.899 --> 00:07:43.839 is consumed purely in the creation of isocyanates. 00:07:43.959 --> 00:07:46.319 And those are the direct precursors to polyurethanes, 00:07:46.420 --> 00:07:48.879 right? Yes. The foams in your furniture, the 00:07:48.879 --> 00:07:51.480 adhesives, felons, and the synthetic fibers you 00:07:51.480 --> 00:07:54.860 interact with daily require phosgene to exist. 00:07:55.300 --> 00:07:59.259 Another 18 % is allocated to synthesizing polycarbonates. 00:07:59.439 --> 00:08:02.019 Which are the tough plastics. Right. The durable 00:08:02.019 --> 00:08:04.860 plastics utilized in your electronics, your eyeglasses, 00:08:05.000 --> 00:08:08.120 and countless medical devices. But the logistical 00:08:08.120 --> 00:08:10.879 challenge of producing millions of tons of a 00:08:10.879 --> 00:08:14.860 highly toxic, insidious gas is immense. You can't 00:08:14.860 --> 00:08:17.610 exactly simply brew it in massive batches and 00:08:17.610 --> 00:08:21.069 store it in giant warehouse vats near residential 00:08:21.069 --> 00:08:23.370 areas. You absolutely cannot. The storage and 00:08:23.370 --> 00:08:25.490 transportation of phosgene are strictly globally 00:08:25.490 --> 00:08:28.149 regulated. Under the Chemical Weapons Convention, 00:08:28.310 --> 00:08:30.810 it is classified as a Schedule III substance. 00:08:31.129 --> 00:08:33.049 What does that classification mean for a factory? 00:08:33.470 --> 00:08:36.210 It means any facility manufacturing more than 00:08:36.210 --> 00:08:39.320 30 tons annually must declare its operations 00:08:39.320 --> 00:08:41.899 and be monitored by the Organization for the 00:08:41.899 --> 00:08:44.539 Prohibition of Chemical Weapons. Which introduces 00:08:44.539 --> 00:08:47.080 an incredible engineering workaround from the 00:08:47.080 --> 00:08:49.639 industry. I like to think of the manufacturing 00:08:49.639 --> 00:08:52.480 process kind of like a high -stakes, continuous 00:08:52.480 --> 00:08:54.940 -slow, single -serve coffee maker. That is a 00:08:54.940 --> 00:08:57.500 very apt analogy. Because rather than brewing 00:08:57.500 --> 00:09:00.080 a massive pot of coffee, or in this case a giant 00:09:00.080 --> 00:09:03.330 vat of deadly gas that just... sits around posing 00:09:03.330 --> 00:09:06.549 a constant threat to the city, the system only 00:09:06.549 --> 00:09:09.090 brews exactly what is required at the precise 00:09:09.090 --> 00:09:11.710 moment it needs to be consumed. The industry 00:09:11.710 --> 00:09:14.690 utilizes an on -demand production model. purified 00:09:14.690 --> 00:09:17.309 carbon monoxide, and chlorine gas are passed 00:09:17.309 --> 00:09:19.429 through a bed of porous activated carbon. The 00:09:19.429 --> 00:09:21.889 carbon acts as the catalyst, right? Yes, at temperatures 00:09:21.889 --> 00:09:25.710 between 50 and 150 degrees Celsius. But crucially, 00:09:25.929 --> 00:09:27.690 the production and the consumption rates are 00:09:27.690 --> 00:09:30.250 tightly synchronized within the exact same facility. 00:09:30.470 --> 00:09:32.830 So they use the phosgene the exact millisecond 00:09:32.830 --> 00:09:36.429 it is created. Exactly. This drastically mitigates 00:09:36.429 --> 00:09:39.350 the risk of a catastrophic leak because the physical 00:09:39.350 --> 00:09:41.470 volume of the gas existing within the system 00:09:41.470 --> 00:09:44.899 at any given second is kept remarkably low. While 00:09:44.899 --> 00:09:47.620 some isolated batch production does occur for 00:09:47.620 --> 00:09:50.700 very specific niche applications, the overarching 00:09:50.700 --> 00:09:54.080 infrastructure we rely on is purposefully designed 00:09:54.080 --> 00:09:57.379 to minimize storage. And obviously the classification 00:09:57.379 --> 00:09:59.980 as a Schedule III substance under the Chemical 00:09:59.980 --> 00:10:02.539 Weapons Convention is a direct reflection of 00:10:02.539 --> 00:10:04.639 its historical deployment. It's impossible to 00:10:04.639 --> 00:10:07.100 untangle the industrial chemical from its military 00:10:07.100 --> 00:10:09.559 history. Here's where it gets really interesting. 00:10:09.940 --> 00:10:12.460 Because the deployment of phosgene in early 20th 00:10:12.460 --> 00:10:15.009 century warfare fundamentally altered the landscape 00:10:15.009 --> 00:10:18.090 of combat forever. It was first utilized as a 00:10:18.090 --> 00:10:20.570 chemical weapon by the French in 1915 during 00:10:20.570 --> 00:10:22.730 World War I. And their tactical application was 00:10:22.730 --> 00:10:25.210 very specific. Yeah, they involved mixing the 00:10:25.210 --> 00:10:27.789 phosgene with an equal volume of chlorine gas. 00:10:28.029 --> 00:10:30.539 Why did they do that? The physics of the battlefield 00:10:30.539 --> 00:10:33.740 necessitated that mixture. Phosgene is a notably 00:10:33.740 --> 00:10:36.200 dense gas, so when it's released it naturally 00:10:36.200 --> 00:10:38.799 sinks down into low -lying areas. Which makes 00:10:38.799 --> 00:10:41.179 trenches incredibly vulnerable. Highly vulnerable. 00:10:41.679 --> 00:10:43.860 However, on its own it doesn't spread fast enough. 00:10:44.059 --> 00:10:46.899 Mixing it with the chlorine enhanced the dispersal 00:10:46.899 --> 00:10:49.559 rate significantly, allowing the much denser 00:10:49.559 --> 00:10:52.419 phosgene to spread far more effectively across 00:10:52.419 --> 00:10:55.720 wider enemy positions. And the resulting lethality 00:10:55.720 --> 00:10:58.519 was just unprecedented. We are looking at 85 00:10:58.519 --> 00:11:01.879 ,000 deaths attributed to phosgene in World War 00:11:01.879 --> 00:11:04.539 I alone. It accounted for the vast majority of 00:11:04.539 --> 00:11:07.070 chemical fatalities in that conflict. Consider 00:11:07.070 --> 00:11:09.070 the psychological implications of those delayed 00:11:09.070 --> 00:11:11.070 symptoms we talked about in a trench warfare 00:11:11.070 --> 00:11:14.429 scenario. Soldiers endure a chaotic gas attack, 00:11:14.870 --> 00:11:17.370 they detect the faint scent of musty hay, they 00:11:17.370 --> 00:11:20.350 survive the immediate chaos, and perhaps they 00:11:20.350 --> 00:11:22.230 genuinely believe they have escaped unharmed. 00:11:22.360 --> 00:11:25.600 only to succumb to fatal pulmonary edema a full 00:11:25.600 --> 00:11:28.039 day later. It is truly haunting. If we connect 00:11:28.039 --> 00:11:30.100 this to the bigger picture, it is vital to analyze 00:11:30.100 --> 00:11:32.240 why a century -old chemical weapon remains so 00:11:32.240 --> 00:11:34.200 closely monitored today. The source material 00:11:34.200 --> 00:11:36.620 explicitly notes that toxicologically speaking, 00:11:36.879 --> 00:11:40.100 modern nerve agents like sarin, tabun, or VX 00:11:40.100 --> 00:11:43.080 are actually far more lethal than phosgene. Right. 00:11:43.299 --> 00:11:46.639 So if the toxicity is comparatively lower than 00:11:46.639 --> 00:11:49.759 those first -generation nerve agents, What maintains 00:11:49.759 --> 00:11:52.440 phosgene's viability as a chemical warfare threat 00:11:52.440 --> 00:11:54.639 today? Why are we still so worried about it? 00:11:54.679 --> 00:11:57.299 The barrier to entry. The manufacturing. Exactly. 00:11:57.519 --> 00:12:00.120 The manufacturing requirements for complex nerve 00:12:00.120 --> 00:12:03.360 agents demand highly technical processes, extremely 00:12:03.360 --> 00:12:06.039 specialized equipment, and tightly controlled 00:12:06.039 --> 00:12:08.919 advanced chemical precursors. Whereas phosgene, 00:12:09.019 --> 00:12:12.080 as John Davy demonstrated in 1812, requires only 00:12:12.080 --> 00:12:15.379 carbon monoxide, chlorine, and a catalyst. And 00:12:15.379 --> 00:12:18.120 sunlight or heat. The sheer ease of production 00:12:18.120 --> 00:12:21.080 makes it exceptionally dangerous for proliferation. 00:12:21.740 --> 00:12:24.000 Following World War I, various nations heavily 00:12:24.000 --> 00:12:27.139 stockpiled the gas for this exact reason. The 00:12:27.139 --> 00:12:29.519 Imperial Japanese Army, specifically the infamous 00:12:29.519 --> 00:12:32.460 Unit 731, produced and infrequently deployed 00:12:32.460 --> 00:12:34.860 it against the Chinese during the Second Sino 00:12:34.860 --> 00:12:37.360 -Japanese War. The simplicity of the synthesis 00:12:37.360 --> 00:12:39.720 ensures that the threat is never truly obsolete. 00:12:39.860 --> 00:12:42.519 Which leads to another critical and frankly scary 00:12:42.519 --> 00:12:45.080 dimension of this compound's chemistry, inadvertent 00:12:45.080 --> 00:12:47.889 generation. You do not need to be an industrial 00:12:47.889 --> 00:12:50.830 chemist or military personnel to encounter the 00:12:50.830 --> 00:12:53.830 synthesis of phosgene. No, you don't. And the 00:12:53.830 --> 00:12:56.210 fire extinguisher paradox is a prime example 00:12:56.210 --> 00:12:58.870 of this inadvertent creation. This blew my mind. 00:12:59.470 --> 00:13:03.429 Historically, carbon tetrachloride or CCl4 was 00:13:03.429 --> 00:13:06.889 heavily utilized in fire extinguishers. It functioned 00:13:06.889 --> 00:13:09.149 as an incredibly effective fire suppressant. 00:13:09.330 --> 00:13:11.789 The physical suppression capability was excellent, 00:13:12.250 --> 00:13:14.769 but the thermal decomposition of the chemical 00:13:14.769 --> 00:13:17.789 presented a completely fatal flaw. What happens 00:13:17.789 --> 00:13:20.230 when it gets hot? When carbon tetrachloride is 00:13:20.230 --> 00:13:23.490 exposed to intense heat in an oxygen -rich environment, 00:13:23.570 --> 00:13:25.710 such as being sprayed directly onto an active 00:13:25.710 --> 00:13:28.590 fire, it undergoes a chemical reaction that rapidly 00:13:28.590 --> 00:13:31.129 converts the suppressant into phosgene gas. The 00:13:31.129 --> 00:13:33.309 tragedy of that chemical reaction is profound. 00:13:33.480 --> 00:13:36.460 people fighting fires in confined spaces successfully 00:13:36.460 --> 00:13:38.740 extinguished the flames, only to perish from 00:13:38.740 --> 00:13:41.000 the invisible gas generated by their own safety 00:13:41.000 --> 00:13:43.059 equipment. The recurring fatalities ultimately 00:13:43.059 --> 00:13:45.799 led to the complete abandonment of carbon tetrachloride 00:13:45.799 --> 00:13:48.019 for fire suppression purposes. It was just too 00:13:48.019 --> 00:13:50.960 dangerous. But inadvertent generation also extends 00:13:50.960 --> 00:13:54.139 to biological metabolism, which is another wild 00:13:54.139 --> 00:13:56.820 layer to this. When a human body is exposed to 00:13:56.820 --> 00:13:59.559 chloroform, the liver immediately attempts to 00:13:59.559 --> 00:14:02.139 process and metabolize the chemical. Yes, and 00:14:02.139 --> 00:14:04.879 this breakdown is likely facilitated by the cytochrome 00:14:04.879 --> 00:14:08.220 P450 enzyme family in the liver. In the resulting 00:14:08.220 --> 00:14:10.639 metabolite, the actual byproduct of your body 00:14:10.639 --> 00:14:13.730 processing the chloroform is phosgene. The liver 00:14:13.730 --> 00:14:16.610 essentially manufactures a chemical weapon internally 00:14:16.610 --> 00:14:19.169 while desperately attempting to clear another 00:14:19.169 --> 00:14:22.610 toxic substance. It is a brutal biological irony. 00:14:23.070 --> 00:14:25.210 Moving back to the industrial sector, despite 00:14:25.210 --> 00:14:27.570 the rigorous on -demand manufacturing protocols 00:14:27.570 --> 00:14:29.909 we discussed earlier, catastrophic inadvertent 00:14:29.909 --> 00:14:32.649 releases still occur in the modern era. The historical 00:14:32.649 --> 00:14:35.370 record is definitely punctuated by severe industrial 00:14:35.370 --> 00:14:38.730 accidents. For instance, in May 1928, a major 00:14:38.730 --> 00:14:40.669 incident occurred in central Hamburg. That was 00:14:40.669 --> 00:14:43.799 the surplus store, right? Yes. 11 tons of phosgene 00:14:43.799 --> 00:14:46.159 escaped from a war surplus store directly into 00:14:46.159 --> 00:14:48.779 the surrounding urban area. The release poisoned 00:14:48.779 --> 00:14:52.159 300 people and resulted in 10 fatalities. And 00:14:52.159 --> 00:14:54.360 the text explicitly outlines that these incidents 00:14:54.360 --> 00:14:56.919 are not just confined to early 20th century surplus 00:14:56.919 --> 00:15:01.409 stores. They happen now. In January 2010, an 00:15:01.409 --> 00:15:03.710 accidental release at a DuPont facility in West 00:15:03.710 --> 00:15:06.769 Virginia resulted in the fatality of one employee. 00:15:07.070 --> 00:15:09.110 The U .S. Chemical Safety Board actually investigated 00:15:09.110 --> 00:15:11.570 that and released a detailed breakdown of the 00:15:11.570 --> 00:15:13.669 specific mechanical failures that led to the 00:15:13.669 --> 00:15:17.429 fatal exposure. And then in May 2016, a phosgene 00:15:17.429 --> 00:15:21.110 leak at a BASF plant in South Korea resulted 00:15:21.110 --> 00:15:24.529 in a contractor inhaling a lethal dose. The intense 00:15:24.529 --> 00:15:26.809 reactivity of the chemical ensures that the margin 00:15:26.809 --> 00:15:29.269 for error within these modern facilities remains 00:15:29.269 --> 00:15:32.019 incredibly narrow. One mechanical failure is 00:15:32.019 --> 00:15:34.340 all it takes. The reporting in our source material 00:15:34.340 --> 00:15:37.539 also covers a very recent event. The 2023 train 00:15:37.539 --> 00:15:39.759 derailment in East Palestine, Ohio. A highly 00:15:39.759 --> 00:15:42.100 publicized incident. A freight train carrying 00:15:42.100 --> 00:15:44.460 vinyl chloride derailed and subsequently burned. 00:15:45.340 --> 00:15:47.220 The combustion of that vinyl chloride released 00:15:47.220 --> 00:15:49.299 phosgene and hydrogen chloride directly into 00:15:49.299 --> 00:15:51.679 the air while also contaminated the Ohio River. 00:15:51.840 --> 00:15:54.120 The East Palestine event highlights a crucial 00:15:54.120 --> 00:15:57.039 point. The primary chemical being transported 00:15:57.039 --> 00:15:59.539 does not even need to be phosgene for a release 00:15:59.539 --> 00:16:02.159 to occur. Right, it was vinyl chloride. Exactly. 00:16:02.559 --> 00:16:05.500 The thermal decomposition of complex organochlorine 00:16:05.500 --> 00:16:08.519 compounds, such as vinyl chloride, can inadvertently 00:16:08.519 --> 00:16:11.320 synthesize phosgene during combustion, rapidly 00:16:11.320 --> 00:16:13.299 dispersing it into the surrounding environment. 00:16:13.460 --> 00:16:15.399 So what does this all mean? We have spent this 00:16:15.399 --> 00:16:18.200 time mapping the profound duality of a single 00:16:18.200 --> 00:16:22.019 chemical compound. Phosgene is a highly toxic, 00:16:22.419 --> 00:16:25.700 insidious gas that fundamentally alters cellular 00:16:25.700 --> 00:16:28.720 architecture. It causes delayed pulmonary edema, 00:16:28.860 --> 00:16:30.879 and it was weaponized to devastating effect. 00:16:31.000 --> 00:16:34.059 Yet simultaneously, it is an absolutely indispensable 00:16:34.059 --> 00:16:36.799 precursor to the polyurethanes and polycarbonates 00:16:36.799 --> 00:16:39.399 that shape modern infrastructure. We maintain 00:16:39.399 --> 00:16:41.860 this vital industrial pipeline by carefully forcing 00:16:41.860 --> 00:16:44.659 the chemical to consume itself the exact second 00:16:44.659 --> 00:16:47.200 it is synthesized, navigating this razor -thin 00:16:47.200 --> 00:16:49.789 line between utility and lethality. This raises 00:16:49.789 --> 00:16:51.649 an important question regarding the long -term 00:16:51.649 --> 00:16:53.889 legacy of our industrial practices, particularly 00:16:53.889 --> 00:16:58.960 concerning atmospheric chemistry. Well, prior 00:16:58.960 --> 00:17:00.980 to the discovery of the ozone hole in the late 00:17:00.980 --> 00:17:05.000 1970s, global industry routinely utilized and 00:17:05.000 --> 00:17:07.940 released massive quantities of simple organochlorides 00:17:07.940 --> 00:17:10.940 into the air. And when those atmospheric organochlorides 00:17:10.940 --> 00:17:13.559 are exposed to ultraviolet irradiation from the 00:17:13.559 --> 00:17:16.880 sun in the presence of ambient oxygen, they slowly 00:17:16.880 --> 00:17:19.980 undergo a chemical conversion into phosgene. 00:17:20.220 --> 00:17:23.200 The sun is executing the exact same catalytic 00:17:23.200 --> 00:17:26.400 process John Davy discovered in 1812, but on 00:17:26.400 --> 00:17:28.940 a planetary scale. that is staggering to think 00:17:28.940 --> 00:17:31.819 about. The atmospheric data from the 1970s and 00:17:31.819 --> 00:17:34.519 80s recorded background levels of phosgene in 00:17:34.519 --> 00:17:37.160 the troposphere, which is the lowest layer of 00:17:37.160 --> 00:17:39.900 Earth's atmosphere, at approximately 20 to 30 00:17:39.900 --> 00:17:42.680 parts per trillion by volume. And it occasionally 00:17:42.680 --> 00:17:44.299 peaked even higher, right? Yes, occasionally 00:17:44.299 --> 00:17:46.559 peaking at 60 parts per trillion. And despite 00:17:46.559 --> 00:17:49.099 international regulations like the Montreal Protocol 00:17:49.099 --> 00:17:51.279 heavily restricting organochloride production, 00:17:51.859 --> 00:17:54.039 those atmospheric levels had not decreased significantly 00:17:54.039 --> 00:17:56.700 even 30 years later. The sheer persistence of 00:17:56.700 --> 00:17:58.660 the The compound in the atmosphere is notable. 00:17:58.799 --> 00:18:00.920 How long does it actually stay up there? In the 00:18:00.920 --> 00:18:03.140 troposphere, phosgene maintains a lifespan of 00:18:03.140 --> 00:18:06.559 up to roughly 70 days. The primary removal mechanism 00:18:06.559 --> 00:18:09.480 is simply hydrolysis. Meaning water breaks it 00:18:09.480 --> 00:18:12.440 down? Precisely. The gas is slowly broken down 00:18:12.440 --> 00:18:14.799 and washed out of the sky by ambient humidity, 00:18:15.099 --> 00:18:18.599 cloud water, and rain. However, the fraction 00:18:18.599 --> 00:18:21.099 of the gas that manages to permeate the drier, 00:18:21.160 --> 00:18:23.660 much higher upper stratosphere can persist for 00:18:23.660 --> 00:18:26.819 several years. Up there, it plays a minor role 00:18:26.819 --> 00:18:29.759 in the broader process of ozone depletion. So 00:18:29.759 --> 00:18:32.859 the ghosts of past industrial conveniences, the 00:18:32.859 --> 00:18:35.440 invisible byproducts of refrigerants and solvents 00:18:35.440 --> 00:18:37.900 utilized decades ago, are currently suspended 00:18:37.900 --> 00:18:40.809 in the atmosphere right above us. They are slowly 00:18:40.809 --> 00:18:43.349 being converted by solar radiation into the very 00:18:43.349 --> 00:18:45.329 chemical deployed in the trenches of World War 00:18:45.329 --> 00:18:48.250 I. It is a sobering reality. And we rely entirely 00:18:48.250 --> 00:18:50.670 on the Earth's natural weather systems, on simple 00:18:50.670 --> 00:18:53.049 precipitation and rain, to continually scrub 00:18:53.049 --> 00:18:55.880 the sky clean of our own industrial legacy. It 00:18:55.880 --> 00:18:58.059 serves as a striking reminder that the chemical 00:18:58.059 --> 00:19:00.799 footprint of human innovation extends far, far 00:19:00.799 --> 00:19:02.940 beyond the immediate utility of the product. 00:19:03.539 --> 00:19:06.099 It requires the planetary ecosystem itself to 00:19:06.099 --> 00:19:09.160 process the invisible consequences. That atmospheric 00:19:09.160 --> 00:19:11.420 reality is definitely something to deeply consider 00:19:11.420 --> 00:19:13.380 the next time you step outside and smell fresh 00:19:13.380 --> 00:19:16.059 rain or catch the scent of freshly cut grass. 00:19:16.970 --> 00:19:19.730 Thank you for joining us on this deep dive. We 00:19:19.730 --> 00:19:22.410 hope this exploration into the complex dual nature 00:19:22.410 --> 00:19:24.789 of phosgene has provided you with a new perspective 00:19:24.789 --> 00:19:27.009 on the chemistry that builds and occasionally 00:19:27.009 --> 00:19:29.609 threatens the world around you. Stay curious, 00:19:29.869 --> 00:19:31.789 keep investigating the hidden mechanics of your 00:19:31.789 --> 00:19:33.710 environment, and we will catch you on the next 00:19:33.710 --> 00:19:34.309 deep dive.