The Hidden Chemistry of Home Products

Are Phthalates the Same as PFAS? Are sVOCs the Same as PAHs? How to Sort the Chemicals in Your Home

There are a lot of ways to organize household chemicals. You could group them by biological effect (endocrine disruptors, carcinogens), by how long they persist in the environment (persistent organic pollutants, “forever chemicals”), by their origin (synthetic vs. naturally occurring). All of these are valid classifications, and a single chemical can belong to several of them at once. A flame retardant, for example, can be an sVOC (semi-volatile organic compound) because of how it moves, and also an endocrine disruptor because it affects your hormones, and also a persistent organic pollutant because of how long it lasts in the environment.

These aren't contradictions, just different ways of classifying the same substance. The problem is, it creates a little mental chaos that I think make everything feel scarier.

The way I like to keep chemicals organized best, and the way that helps you understand what's actually happening inside your home, and eventually how much that poses a risk to you, is behavioral: how does the chemical or substance physically move?

There are three major ways that chemicals travel from a product into your home environment, and once you understand them, you can look at almost any item in your house and start predicting what types of chemicals might be present, and if and how they'd get out.

1. VOCs: Substances That Become Gas

Volatile Organic Compounds, or VOCs, are chemicals that convert from a liquid or solid into a gas at regular room temperature. That conversion happens on its own, without any contact, friction, or heat required. If you've ever noticed the "new car" or "new furniture" smell, you've detected VOCs. They move freely through indoor air, and most standard air filters can't capture them because they're extremely small molecules, not particles, which HEPA filters easily catch.

VOCs are released most heavily when a product is new, and less as time goes by, because the volatile compounds eventually are all released from the product.

• Formaldehyde is a common VOC found at home that comes primarily from the glues mixtures used in pressed-wood products like particleboard, MDF, and plywood to keep the wood particles and dust in “wood shape.” This is what most IKEA and other flat-pack furniture is made out of, as well as cabinetry, and some flooring. Formaldehyde is also a component of wood glue and fabrics are often treated with formaldehyde-releasing resins to keep them wrinkle-free.

• Toluene and Xylene are common VOCs that are found in paints, stains, lacquers, and adhesives. They're solvents that keep the paint a liquid. They’re part of the reason why fresh paint has a strong smell that fades over time.

• Undisclosed VOC Mixtures: Candles, air fresheners, and scented products are composed of mixtures of VOCS that are designed to smell good. This includes synthetic fragrances as well as natural essential oils.

2. sVOCs: Substances That Migrate Slowly

Semi-Volatile Organic Compounds (sVOCs) are a little strange, because their behavior is less intuitive. They’re definitely in a separate category than regular VOCs because sVOCs don't become gas and drift away. But, they also aren't locked permanently in place.

VOCs escape products easily on their own, straight into the air. Even an unlighted scented candle will release VOCs. An sVOC, however, moves a little differently, more like butter left on the countertop. It migrates onto the butter dish, but gradually, driven by heat, friction, and time rather than simple evaporation into the air. sVOCs leave their source material and end up on surfaces, in household dust, and on other objects nearby. The primary place they collect is in on surfaces and in dust, not air.

• Phthalates are sVOCs. They’re a special type of sVOC, a plasticizer. Plasticizers are added to PVC to make it flexible. They are not chemically bonded to the plastic, which is why they migrate out of it continuously. Vinyl flooring (including “luxury” vinyl plank) is one of the most significant residential sources.

• PFAS (per- and polyfluoroalkyl substances) are also a type of sVOC. PFAS are common in the home as surface treatments applied to upholstery, carpet, rugs, cookware, and food packaging to resist water, oil, and stains. Where phthalates are plasticizers designed to make materials soft, PFAS are surface coatings designed to make materials repel liquids. What they share is the way they migrate: slowly, into dust and onto surfaces.

• Flame retardants also fit best into the sVOC category. They’re added to foam furniture, mattresses, carpet padding, curtain fabric, and electronics. There are hundreds of types of flame retardants, and most of them are considered sVOCs because they’re able to migrate from foam and other products into household dust over time.

• Heavy siloxanes are sVOCs that are released from silicone-containing products, including sealants, caulks, silicone bakeware and silicone-treated water-resistant fabrics over time. (Lighter forms of siloxanes can volatilize straight into the air as regular VOCs.)

• Naphthalene, is an sVOC that is not only the active ingredient in traditional mothballs, but is also used in the creation of caulk, carpet pads, and other building materials. In addition to being an sVOC, you can also classify it as a polycyclic aromatic hydrocarbon (PAH). PAHs are a chemical structure classification, not a behavioral class.

3. Particles: Physical Fragments of Things

Particles, also called Particulate Matter, or PM2.5, or even PM10, are solid pieces of material. Unlike VOCs and sVOCs, which are individual chemical molecules, particles are physical fragments. They are defined entirely by their size, not by their chemistry, and they are generated by friction, abrasion, deterioration, and combustion.

Size determines how they behave. Larger particles (PM10 and above, like dust you can see) settle out of the air relatively quickly and become part of household dust on surfaces and the floor. Fine particles (PM2.5) stay airborne for hours and travel freely through the home. Ultrafine particles (PM1 and below) do, too.

Particles also act as carriers for sVOCs, meaning chemicals like flame retardants and PFAS can catch a ride on particles and move around your house that way.

• Microplastics and microfibers are shed from synthetic textiles like polyester curtains, carpet, and clothing during normal use. They are a type of plastic particle released through friction and wear. Microplastics have been found in indoor dust, air, and drinking water.

• Foam fragments break off from deteriorating cushions, mattresses, and carpet padding through compression and friction over years of use. Because flame retardants are embedded in the foam, these fragments can carry sVOCs into dust.

• Combustion particles are generated by cooking (especially frying and high-heat methods), burning candles, and gas stoves. These particles are chemically complex: they carry adsorbed organic compounds, metals, and other substances on their surfaces.

• Heavy metals are generated when surfaces containing lead, cadmium, or arsenic experience friction, like windows being opened and closed, doors rubbing against lead-painted frames, or scraping an arsenic-containing piece of cookware with a metal spatula. Heavy metals can travel through the home as particles (paint chips and dust), on other particles (adsorbed onto PM2.5), or as particles dissolved dissolved in water. But, they don’t behave like VOCs or sVOCs.

• Asbestos fibers are released from building materials in pre-1980 homes when those materials become friable (crumbling) or are disturbed during renovation. Intact, undisturbed asbestos materials are generally stable. The hazard is in the disturbance.

• Engineered nanomaterials like nano-titanium dioxide and nano-silver are intentionally manufactured to be extremely small (1 to 100 nanometers). At this scale, they can cross biological membranes that larger particles cannot. They appear in some nonstick coatings, antimicrobial textiles, and paints. By movement behavior, they are particles. But their engineered size gives them access to biological pathways that conventional particles don't reach, which is why they are sometimes discussed as their own category.

Bonus: UVCBs, or When the Categories Mix Into Unknowns

Some manufactured substances are complex mixtures with variable, sometimes completely unknown composition. In regulatory science, these are called UVCBs: substances of Unknown or Variable composition, Complex reaction products, and Biological materials. Fragrance blends, certain petrochemical byproducts, and some tanning agents fall into this category.

The issue with UVCBs is that they contain components across all three behavioral categories in unknown ratios. A single fragrance mixture might include VOCs that off-gas, sVOCs that migrate into dust, and particle-bound compounds, all in proportions that aren't disclosed and may not even be fully characterized by the manufacturer. This makes it genuinely difficult to predict how the mixture as a whole will behave in a home environment.

TSCA (the main U.S. chemical regulation law) often treats these as single substances, but they behave as unpredictable combinations. This is one of the real gaps in chemical regulation, and one reason why "fragrance" as a single line item on an ingredients list can represent dozens of individual chemicals moving through your home in different ways.