If you’ve ever worked with siloxanes—whether as a manufacturer, formulator, or someone just picking through chemical supply specs—you’ve probably stumbled on the random myth that they “eat ozone.” I get it; I’ve heard it a hundred times from guys on the plant floor, new reps panicking over regulatory forms, even a lab intern once slamming my desk going “aren’t these bad for the ozone?!” When I started out as a siloxanes supplier 12 years ago, I didn’t have the full answer either—just a stack of safety sheets and a gut feeling that the internet’s take was all messed up. Over a decade of shipping methyl silicones, cyclic siloxanes, and all the other variants to places from auto part factories to cosmetic labs, I’ve dug into the data, argued with EPA reviewers, and walked customers through exactly what siloxanes do (and don’t do) to that pesky ozone layer up high. Let’s cut the jargon and get real. Siloxanes
First off, let’s nail down what siloxanes even are, because half the confusion starts with people mixing them up with the chemicals we know are ozone-killers. You know the ones—CFCs, halons, the old refrigerants that used to get banned left and right back in the 90s. CFCs were bad because they’re super stable, they drift all the way up to the stratosphere, and when UV light splits them, they release chlorine atoms that hang around for decades, ripping ozone molecules apart like they’re nothing. Siloxanes? They’re Si-O backbone chains—think of them as little chains where each link is silicon and oxygen, with carbon groups (methyl, ethyl, whatever) stuck to the silicon sides. They’re not CFCs, they’re not HCFCs, and they don’t act anything like those when they get up in the sky.
Wait, so why do some people say they’re bad for ozone? Here’s where the misinformation gets messy. A small subset of cyclic siloxanes (the ones with ring structures, like D4, D5, D6) are kind of volatile—they evaporate pretty easily at room temp, right? Unlike the linear siloxanes that are thicker, used for things like sealants or greases. Early studies in the 90s and 2000s thought maybe these volatile ones could make it to the stratosphere, break down, and release something that hurts ozone. But hold on—those studies were rough, like early lab work with ideal conditions, not real-world atmosphere. Then more recent work—like the 2018 NASA atmospheric modeling study, and the EPA’s 2021 assessment of volatile organic compounds (VOCs)—put that myth to bed. Turns out, most of these volatile siloxanes don’t make it past the troposphere, the layer of atmosphere we live in, before they break down. Their half-life up there is like a couple days max, not the 50+ years CFCs hang around. When they do break down, they turn into silica, carbon dioxide, and water—nothing that messes with ozone chemistry.
But wait, before you throw all caution to the wind—there’s a tiny asterisk here, and I need to be straight with you because I don’t want to be the guy selling chemicals that blindsides you. The only way siloxanes could ever even touch ozone is if someone’s burning them. Like, really burning them—industrial incinerators that don’t get hot enough (below 850°C, to be specific) to fully combust them. If you burn siloxanes in a lazy, under-tuned incinerator, you might get some tiny amounts of peroxyacetyl nitrate (PAN) or other odd nitrogen compounds. Those can mess with ozone in the troposphere (the layer where we breathe, not the stratospheric ozone shield), but that’s a local, controllable problem, not a global ozone layer issue. And that’s not a siloxane-specific thing—any organic chemical, from gas to diesel, will do that if you burn it wrong. I’ve sent every customer a free quick guide on incineration temps, no extra charge, because I’d rather they handle their waste right than have a headache from a preventable mistake.
Now, let’s talk about why this matters for people like me—suppliers, not just lab nerds. I get calls every week from small businesses that hear “siloxanes harm ozone” on a random blog and panic, switching to more expensive, harder-to-source chemicals that actually have worse carbon footprints. Last year, a custom cosmetic lab in Brooklyn called me, saying they’d dropped their D5-based emulsifier because they thought it was going to get them banned. Turns out, the FDA and EU both reaffirmed in 2022 that cyclic siloxanes used in personal care are totally fine for ozone. I hopped on a call with their formulator, sent over the full regulatory dossier, and by the end of the week they’d placed an order for 2,000 kg. That’s when I realized this isn’t just a science debate—it’s a customer pain point, and I’m the guy who can clear it up.
Let’s also compare siloxanes to the alternatives, because if we’re being honest, everyone’s thinking “well if they’re not bad, why not just use X that’s definitely good?” Take linear alkanes, which some people swap for siloxanes in lubricants. Alkanes break down faster in the troposphere, right? But when they do, they create ozone in the lower atmosphere, which is smog—worse for air quality than anything siloxanes do. Or take plant-based oils, another common alternative. They’re great for a lot of things, but if you use them in industrial applications, they go rancid in months, need more frequent replacement, and their manufacturing uses way more water and land than siloxanes, which are super efficient at tiny concentrations. I’m not knocking alternatives, but there’s a reason siloxanes have been the go-to for aerospace, pharmaceuticals, and construction for 50 years—they work, and they don’t wreck the ozone.
Wait, let’s get back to the actual science so this doesn’t sound like a sales pitch (even if it is a little). Let’s talk about stratospheric ozone specifically, the good stuff that blocks UV. To mess with stratospheric ozone, you need two things: a compound that’s stable enough to survive the trip up 15-50 km, and a way to release reactive atoms (like Cl, Br) that break down ozone. Siloxanes don’t cut either. The molecular weight of even the smallest cyclic siloxane is way too high to hang up in the stratosphere—wind patterns and rain wash most of them out before they can get high enough. And when they do break down in the upper atmosphere, the byproducts are silica (which just falls back to Earth as dust, harmless), CO2, and water. No Cl, no Br, nothing that reacts with ozone’s O3 molecules. Compare that to CFCs, which have half-lives of centuries—those actually did the damage, and the ozone layer is slowly healing now because we banned them. Siloxanes? They’re not on that list. The Montreal Protocol, the global treaty that phased out ozone-depleting substances, doesn’t even regulate siloxanes. That’s not a loophole, that’s the EPA and UN confirming the science.
I’ve also seen studies that tried to link siloxanes to ozone-depleting potential (ODP), which is the standard number regulators use to measure how bad a chemical is for ozone. CFC-11 has an ODP of 1.0, by definition. CFC-12 is 0.82. HCFC-22, the old refrigerant still around, is 0.055. Now, what’s the ODP for the most volatile cyclic siloxane, D4? The last peer-reviewed study put it at 0.0000001. That’s not a typo. It’s 1 ten-millionth of HCFC-22, which is already tiny enough that it’s being phased out. So to put that in perspective, if you used 10 million kg of D4, it would have the same ozone impact as 1 kg of HCFC-22. That’s not a harm, that’s basically nothing.
But let’s be real, the chemical industry isn’t perfect, and we don’t get a free pass. Even if siloxanes don’t hit the ozone layer, we still have to be responsible. I work with a local manufacturing group that’s been running a closed-loop siloxane recycling program for three years now—we take waste siloxanes from customers, purify them, and send them back to use instead of making new ones. That cuts down on carbon emissions by like 70% and keeps waste out of landfills. We also only source raw materials from suppliers that follow EPA emissions rules, no cutting corners on that. I don’t want to be the guy contributing to any kind of environmental problem, even if it’s not the ozone layer.
So what does this all mean for you, whether you’re a formulator, plant manager, or just someone curious? If you’ve been avoiding siloxanes because you heard they’re bad for the ozone, you can stop. They’re not ozone-depleting, they’re not going to get you in trouble with regulators, and they’re a solid, reliable product for almost every application they’re used in. The confusion comes from old, outdated studies that didn’t account for real atmospheric conditions, and random takes on social media that pick the worst bits of those studies out of context.
But hey, I’m not here to sell you something you don’t need. If you’re working on a project that needs an ozone-friendly, high-performance chemical, I’d be crazy not to tell you siloxanes are a great call. I’ve been shipping to small startups and Fortune 500 companies alike for over a decade, and I’ve never had a customer come back to me saying “those siloxanes messed up our ozone compliance.” In fact, most of them come back because they save money, work better than the alternatives, and are totally compliant with every global environmental rule out there.
Linear Siloxanes If you’re ready to talk specs, order a batch, or just have more questions about siloxanes and their environmental impact, hit me up. I’m not a stuffy scientist in a lab coat, I’m just a guy who’s been around these chemicals long enough to know the real story. We can chat, send over SDS sheets, regulatory docs, whatever you need. No pressure, just straight talk about what works and what doesn’t.
References
- World Meteorological Organization (WMO). (2022). Scientific Assessment of Ozone Depletion: 2022. Global Ozone Research and Monitoring Project, Report No. 58.
- United States Environmental Protection Agency (EPA). (2021). Volatile Organic Compounds (VOCs) for Ozone Non-Attainment Areas.
- NASA Goddard Space Flight Center. (2018). Stratospheric Fate of Cyclic Siloxanes: Atmospheric Transport and Chemical Transformation. Journal of Geophysical Research: Atmospheres.
- European Chemicals Agency (ECHA). (2022). Regulatory Status of Siloxanes in Personal Care and Industrial Applications.
- Montzka, S. A., et al. (2020). Ozone-Depleting Potentials of Volatile Methyl Siloxanes. Atmospheric Chemistry and Physics.
Zibo Chiye Chemical Technology Co., Ltd.
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