Low-VOC Paint and Off-Gassing: What the Number on the Can Measures, and What It Leaves Out

Written By Bayron Alvarez
By Bayron Alvarez, NYS Licensed Mold Assessor (#25-671AE-SHMO) and NYS Licensed Home Inspector (#16000145204) — Casablanca Environmental & Building Diagnostics, Southampton, NY

A common indoor air quality request on the East End follows a repaint. Every can said zero VOC, and three weeks later the bedrooms still smell of fresh paint, someone in the family has headaches or a rash, and the painter has said there is nothing in the product that could cause it. The label was accurate. It was answering a different question than the one the owner is asking.

Low-VOC and zero-VOC paints are a real improvement over the paints sold twenty years ago, and I recommend them. The problem is what the VOC number was written to do. It is a regulatory number, established to reduce ground-level ozone outdoors, measured on the untinted base, and defined in a way that excludes several of the compounds a paint releases into a closed bedroom. This article explains what the number measures, what it leaves out, what a zero-VOC paint still emits and for how long, why the safety data sheet will not answer the question, how the industry responded to the rule, and what to look for instead.

Summary

The VOC limit on architectural paint comes from a 1998 EPA rule issued under Section 183(e) of the Clean Air Act to reduce ozone, and from stricter New York State limits adopted for the same purpose. No federal agency regulates what a paint emits into the room after it is applied. The definition excludes compounds that do not form ozone, whatever they do when inhaled, and the number is measured before colorant is added. A paint that is zero VOC by that definition still releases ammonia, coalescing solvents, glycols, and preservative compounds, some for months. Low-VOC paint remains the safer choice, because emissions do track content across product types. Choosing beyond the number means a chamber emissions certification, a published ingredient list, a zero-VOC colorant system, and a preservative you can identify.

The VOC number on the can is an ozone rule

The federal limits are in 40 CFR Part 59, Subpart D, published September 11, 1998. The rule's stated basis is that "VOC emissions from the use of architectural coatings have the potential to cause or contribute to ozone levels that violate the national ambient air quality standards (NAAQS) for ozone." The health effects it describes are the effects of ozone; it contains no indoor exposure rationale. The limits were 250 grams per liter for flat interior paint and 380 g/L for nonflat, and they have not changed since.

New York adopted stricter limits in 6 NYCRR Part 205, based on the Ozone Transport Commission model rule: for coatings manufactured on or after January 1, 2021, 50 g/L for flat, 100 g/L for nonflat, 150 g/L for nonflat high gloss, and 100 g/L for primers, sealers, and undercoaters. The reason is local. Suffolk County is part of the New York–Northern New Jersey–Long Island ozone nonattainment area, classified Serious under the 2015 ozone standard with an attainment deadline in 2027. The number on a can of paint sold in Southampton exists to help the region meet that deadline.

EPA states the distinction itself. Its indoor air program writes that "the regulations that we have promulgated for VOCs in architectural coatings and consumer products are in place only because many VOCs photochemically react in the atmosphere to produce ozone, a component of smog," that "EPA has no authority to regulate household products (or any other aspect of indoor air quality)," and that "some products that are labeled as 'no VOC' or 'low VOC' under the CAA can actually contain volatile organic chemicals that are toxic, sometimes at high levels." No U.S. agency sets a limit on what the dried film releases into a bedroom.

What the definition leaves out

Compounds that do not form ozone. The definition at 40 CFR 51.100(s) covers any carbon compound "which participates in atmospheric photochemical reactions." Compounds EPA finds to have negligible photochemical reactivity are removed from it, among them acetone (1995), methyl acetate (1998), tert-butyl acetate (2004), and 2-amino-2-methyl-1-propanol (2014), the amine that replaces ammonia in low-odor latex paints. Exemption is a smog decision, not a toxicity decision. EPA's indoor air office states that exempted compounds "could pose serious health risks to exposed individuals if present indoors" and names methylene chloride, the paint stripper solvent, as an example. For indoor air, the definition is by volatility instead: the European Union defines a VOC as any organic compound with an initial boiling point at or below 250°C, and EPA's indoor air program reproduces that definition alongside the World Health Organization's boiling-point classes. Texanol, the most common coalescing solvent in latex paints, boils at 254°C; its manufacturer's data sheet states that under EPA Method 24 Texanol "is considered 100% VOC" and that under the European boiling-point definition it "is not considered a VOC." Whether the most common paint solvent counts depends on which regulation is asking.

The colorant. Under 40 CFR 59.406, "the VOC content of a tint base shall be determined without colorant that is added after the tint base is manufactured or imported." New York's rule says the same at 6 NYCRR 205.6(a). Conventional universal colorants contain roughly 325 g/L of VOC, and a gallon takes from half an ounce for a pastel to 12 ounces for a deep color, according to the South Coast Air Quality Management District's 2011 staff report. In 2011 the National Advertising Division reviewed a zero-VOC line whose deep-base colors, tinted with conventional colorants, measured 42 to 112 g/L, and in 2012 the FTC settled with two manufacturers over zero-VOC claims that were true for the base and not for the tinted product. The South Coast district has limited colorants to 50 g/L at the point of sale since 2014, and other California districts have adopted the same limit. New York has no colorant limit.

The words "low" and "zero." EPA defines neither term. The industry convention is that zero VOC means less than 5 g/L, a level the reference test cannot resolve: EPA Method 24 weighs what evaporates from a sample at 110°C for one hour and subtracts the water, and a study prepared for the California Air Resources Board found its error reaching 1,000 percent below 50 g/L. In 2017 the FTC brought cases against four paint companies for unqualified zero-VOC and emission-free claims, and its statement on the cases applies to every can on the shelf: "All paints emit chemicals during the painting process and while drying."

What a zero-VOC paint still emits

A waterborne interior paint is roughly half water, with the binder, titanium dioxide, and mineral extenders making up most of the rest. The additives are a few percent of the can and produce most of what an occupant breathes: a coalescing solvent that softens the binder particles so they fuse into a film, glycols for freeze-thaw stability and open time, ammonia or an amine to hold pH, an in-can preservative, and often a dry-film mildewcide. The smell of fresh latex paint is largely the ammonia, which is inorganic and not a VOC under any definition; people detect it above about 5 parts per million, and it is an irritant.

Coalescing solvents and glycols are the long emitters. Texanol emissions fall about 90 percent in the first 100 hours, and emissions from painted surfaces have been measured for as long as 15 months. Berkeley Lab measured Texanol and ethylene glycol in new houses one to nine and a half months after completion and reported that emissions from latex paint on gypsum board "can persist at elevated levels for a number of months." EPA chamber studies explain why: the same paint emitted for three to four days on stainless steel and for more than 200 days on gypsum board, because the board absorbs the compounds during painting and re-emits them. Ethylene glycol is odorless. A Swedish case-control study of 400 preschool children found that propylene glycol and glycol ethers in bedroom air were associated with a 1.5-fold greater likelihood of asthma and 2.8-fold for rhinitis, and identified water-based paint as a source.

Preservatives. Most water-based paints contain an isothiazolinone in-can preservative. A Danish study of 19 paints found methylisothiazolinone in all 19 and measured its emission from painted surfaces for more than 42 days. It is a potent skin sensitizer. In a French and Belgian series of 44 patients with airborne allergic contact dermatitis from wall paint, 79.5 percent of exposures were non-occupational, and patients needed a median of 5.5 weeks before they could enter a freshly painted room without a flare. The European Union has required labeling of mixtures containing it at 15 ppm or more since 2020. The United States has no equivalent requirement, and the preservative does not appear on the can.

Formaldehyde. EPA's laboratory tested four paints marketed as low-VOC in 1999. The low VOC emissions were confirmed, and two of the four emitted significant formaldehyde. A follow-up study traced it to the biocide used to preserve the paint and measured a slow-decay stage lasting more than a month. Formaldehyde is an IARC Group 1 carcinogen with an odor threshold near 0.8 ppm, more than 100 times the 7.3 ppb limit used by the emissions certifications below. It is not smelled at the concentrations that matter.

A 2024 analysis of 40 best-selling water-based paints, most labeled zero or low VOC, found isothiazolinone preservatives in almost half and ethylene glycol in 15. EPA's summary applies: VOC labels and certification programs "may not properly assess all of the VOCs emitted from the product," and "[t]his is especially true of most wet products, such as paints or adhesives that may be labeled as 'low-VOC' or 'zero VOC.'"

None of this is an argument for conventional paint. Across product types, emissions follow content: a 2021 study of solvent- and water-borne coatings reported that "[t]he trend in the VOC emissions qualitatively tracks the VOC content reported on the product labels." The first decision, a low-VOC waterborne paint, is correct. The remaining decisions concern what the number does not cover.

Why the safety data sheet will not answer the question

Owners and painters sometimes send me a safety data sheet as evidence that a paint is safe for a nursery. The SDS is an OSHA document under 29 CFR 1910.1200 whose stated purpose is "to ensure that the hazards of all chemicals produced or imported are classified, and that information concerning the classified hazards is transmitted to employers and employees." It does not apply to consumers, and a retailer is not required to give one to a homeowner. Sections 4 through 8 cover first aid, firefighting, spill response, handling and storage, and protective equipment, so that a worker or an emergency responder knows what to do with the product in a drum.

Section 3 lists only ingredients classified as hazardous and present above a cutoff, generally 1 percent, or 0.1 percent for carcinogens and sensitizers, and the manufacturer may withhold an ingredient's identity as a trade secret. The sheet applies to the product "as shipped," before tinting, and the toxicology section for a mixture is commonly marked "not available." The SDS for one widely specified contractor-grade zero-VOC interior eggshell lists three ingredients totaling less than 1.5 percent of the can, a clay, an alkylphenol ethoxylate surfactant, and a biocide, followed by a statement that no additional ingredients require reporting. Nothing on the sheet addresses emissions after the paint dries. That is the sheet doing what the regulation asks of it. The can label, governed by the Federal Hazardous Substances Act, addresses handling hazards in the same way. No U.S. rule requires a paint manufacturer to disclose its full ingredient list, which is why the products that do are notable.

What the industry did with the rule

The reformulation of American paint came from regulation, and the industry opposed it. Commenters on the 1998 federal rule told EPA that compliant coatings were "too thick and require considerable thinning to apply, are less durable and require more frequent repainting, and exhibit poor gloss properties," while EPA's own 1990 industry survey found that 64 percent of the products already met the limits. When the South Coast district in California moved flat paint to 100 g/L in 2001 and 50 g/L in 2008, Sherwin-Williams sued to stop it and lost; the Court of Appeal noted that manufacturers' own data sheets showed low-VOC flats comparable to high-VOC flats, that Glidden had introduced a zero-VOC interior flat in 1992, and that nine other manufacturers were offering zero-VOC flats by the end of 1996. The limits held, the products followed, and the zero-VOC lines sold on the East End today are the result.

Reformulation is also where the economics of paint show. Titanium dioxide, the white hiding pigment, is the most costly ingredient in the can; when its price rose by roughly half between 2010 and 2013, formulators replaced 5 to 15 percent of it with extenders and hollow polymer beads. The technical director of the Master Painters Institute has described how a lower-priced paint is made: "You reduce the expensive components, which are the resin and the hiding pigment, and you also reduce the total solids in the can." Economy flats are formulated above the critical pigment volume concentration, where there is not enough binder to coat the pigment and extender particles; the air voids in the film add hiding and remove scrub resistance. A quality latex paint carries 35 to 45 percent volume solids, economy paints less than 30 percent, and the balance is water. Within one manufacturer's line, price is the most reliable signal of what is in the can.

That is a separate question from VOC content. The early low-VOC paints did have problems with open time, durability, and application; those problems were solved with non-volatile coalescents and new binder chemistry. When Consumer Reports tested interior paints in 2010, "nearly all the top-scoring paints" were at 50 g/L or less, and MPI's X-Green designation requires a product to pass the same performance standard as the conventional product in its category in addition to its VOC content and emissions criteria. A paint without formaldehyde donors, ammonia, or a mildewcide is not a lesser paint. It was formulated to a different specification, and it costs more because the additives it omits were the inexpensive way to solve shelf life, freeze-thaw stability, and film formation.

What to look for instead

A chamber emissions certification. The standard behind the indoor emissions certifications is the California Department of Public Health Standard Method v1.2, often called Section 01350. Paint is applied to gypsum board at 350 square feet per gallon, conditioned for 10 days, and tested in a chamber for 96 hours; the pass/fail measurement is taken at day 14, and each of 35 target compounds must be at or below one-half of California's chronic reference exposure level, except formaldehyde, which is held to its full reference level of 9 micrograms per cubic meter (7.3 ppb). The method's authors chose 14 days because it "represents an early, but realistic, time for first occupancy after new building construction or major renovation." UL GREENGUARD Gold and SCS Indoor Advantage Gold apply the same method, and GREENGUARD Gold adds a total VOC limit of 220 µg/m³. Green Seal GS-11 Edition 4.0 (2021) now requires the CDPH test in addition to content limits, prohibits formaldehyde donors, and caps the tinted product at 50 g/L above the limit allowed for the untinted product.

A certificate describes emissions on days 11 through 14, measured in a chamber ventilated at one air change per hour and scaled to a modeled private office. It does not describe the first three nights, and it does not cover the tinted product unless the certificate says so. It is the best available measure, and it is a floor.

A published ingredient list. A Declare label from the International Living Future Institute discloses ingredients to 100 ppm, and a Health Product Declaration to 1,000 ppm or, at the manufacturer's option, 100 ppm. This is rare in paint. A manufacturer that publishes the list has answered the preservative, ammonia, and formaldehyde-donor questions before you ask.

A zero-VOC colorant system. Ask which colorant the tint machine dispenses into the base you are buying. Benjamin Moore's Gennex and Sherwin-Williams' ColorCast Ecotoner systems are formulated to add no VOC; a conventional universal colorant is not.

Two manufacturers that go further. The mainstream zero-VOC lines stocked on the East End, Benjamin Moore Eco Spec (Green Seal certified, tinted with Gennex) and Sherwin-Williams Emerald and SuperPaint with Air Purifying Technology (GREENGUARD Gold, tinted with ColorCast Ecotoner), are emissions-certified and a reasonable choice for most rooms. They do not publish ingredient lists, and their preservative and mildewcide packages are not disclosed. Two smaller manufacturers go further, and they are the ones I name for nurseries, bedrooms, and occupants with asthma or chemical sensitivity.

AFM Safecoat Zero VOC (flat, eggshell, pearl, and semi-gloss) is made by American Formulating & Manufacturing in San Diego, founded in 1983 around its founder's chemical sensitivities and developed with allergists and environmental medicine physicians. Its technical data sheets state that the paint "contains no formaldehyde, ammonia, aromatic hydrocarbon compounds, exempt solvents or hazardous air pollutants" and is "made without formaldehyde preservatives or toxic mildewcides or fungicides." The line was certified to SCS Indoor Advantage Gold, and zero-VOC colorants are available through its dealers. AFM does not publish a full ingredient list. It sells only through independent dealers, none on Long Island, and ships to order at roughly $85 per gallon.

ECOS Paints (Imperial Paints LLC, Spartanburg, South Carolina) publishes an ingredient list on every product page; its eggshell lists 14 entries, including an acrylic and vinyl acetate binder, ammonia as a pH stabilizer, and hydrogen peroxide and a sodium salt as preservatives, with no isothiazolinone on the list. ECOS states that its paints conform to CDPH 01350 emissions testing at 11, 12, and 14 days, carries a Declare label, and tints with zero-VOC pigments. It should also be said that Imperial Paints is one of the four companies in the FTC's 2017 cases, under a consent order through 2038, because its earlier zero-VOC and baby-safe claims were made without adequate substantiation; the FTC did not find the paint unsafe, and the company's current claims are footnoted to the emissions test. ECOS sells online only, at $97.95 per gallon for eggshell.

Painting sequence and ventilation

Paint before furniture, rugs, and bedding go in, because porous furnishings absorb the emissions during painting and re-emit them for months. Keep windows open and a box fan exhausting from the room during painting and for two to three days afterward, which is EPA's recommendation, and keep the room out of use for that period. For a nursery, a pregnant occupant, or a household member with asthma or chemical sensitivity, I recommend 14 days of ventilation before the room is occupied overnight, the first-occupancy assumption built into the emissions standard, and a paint from the manufacturers above. Heat and humidity increase emission rates. Do not store opened cans in the house.

On the East End the failure I see most often is a house painted in May and closed with the air conditioning at a low setpoint until the family arrives in July. A closed, conditioned house has a low air change rate, and the emissions that would have left through open windows accumulate instead. If a painted house is going to sit, leave ventilation running, or schedule the painting for after the season.

If a recently painted house has a persistent odor or a family member has symptoms that began after the work, an indoor air quality assessment documents the condition. We record total VOC and formaldehyde screening readings room by room against outdoor readings with a TSI Q-Trak XP, along with temperature, relative humidity, dew point, carbon dioxide as a ventilation indicator, and particulates. Where a specific compound needs to be identified, we collect an EPA Method TO-15 canister sample, analyzed by GC/MS for 74 target compounds, and a passive formaldehyde sampler; canister analysis runs approximately $550 to $630 at the laboratory and is itemized separately. The report ranks the corrections: source control first, then ventilation, then filtration. Call or text (631) 655-9855 or email bayrona@casablancaebd.com to schedule.

Common questions about paint off-gassing

Is zero-VOC paint odorless? No. The smell of fresh latex paint is mostly ammonia and the coalescing solvent, and zero-VOC products emit both unless the formula omits them. Odor is also not a measure of hazard: ethylene glycol is odorless, and formaldehyde cannot be smelled below roughly 0.8 ppm.

How long does paint off-gas? Most of the volatile emission leaves in the first two to three days. Coalescing solvents and glycols continue for weeks to months, methylisothiazolinone for more than six weeks, and formaldehyde from the preservative for more than a month. The materials in the room absorb these compounds and re-emit them after the paint has stopped.

Does the VOC number change when the paint is tinted? Yes, unless the store uses a zero-VOC colorant. The number on the can is measured on the untinted base by regulation, conventional colorants run about 325 g/L, and deep colors take the most colorant.

Does a GREENGUARD Gold seal mean the paint emits nothing? No. It means that on day 14 in a test chamber the paint met a total VOC limit of 220 µg/m³, a formaldehyde limit of 7.3 ppb, and per-compound limits at half of California's chronic exposure levels. It is the right thing to look for, and it does not describe the first few days.

East End questions

The house was painted in May and closed with the air conditioning running. In July the paint smell is still there. Is that the paint? Probably, and the house is the reason. A closed, conditioned house has a low air change rate, so emissions that would have been diluted through open windows accumulate and are absorbed by furnishings. Open the house when weather allows, run exhaust fans, and if the odor or symptoms persist, room-by-room readings against the outdoor reading will establish whether the paint is still the source.

We are painting a nursery in Sag Harbor before the baby arrives. What do you recommend? A paint from one of the two manufacturers above, or a GREENGUARD Gold or Green Seal certified line tinted with a zero-VOC colorant; painting before the furniture goes in; and 14 days of ventilation before the room is used overnight. Order early. AFM and ECOS ship to order, and the lead time is part of the schedule.

My painter buys from the local Benjamin Moore or Sherwin-Williams store and says everything is zero VOC now. The base is zero VOC by a definition written for smog, and both stores carry emissions-certified lines. Ask for that line, ask which colorant the store used, and ask which preservative is in it. A painter who can answer all three is using the right product.

Sources and further reading

Bayron Alvarez
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