Suppose a laboratory reports 3,500 mg/kg of lead for an old door coating, that is 0.35 percent by mass. Is that a lot? Is it now a "lead paint" that must be remediated? The value sits in an awkward middle: almost forty times what new paint may contain today, yet one to two orders of magnitude below a classic lead-white coating. Not nothing, but not an obvious lead paint either. What is it, and why is there lead in it at all?
It is precisely this intermediate range, roughly between one tenth and a full percent by mass, where most of the confusion arises. Above about one percent everyone agrees, below about one hundredth of a percent too. In between, the yardsticks collide. This page first explains why an old coating lands in this range, then places the value against every yardstick that actually exists, and shows how lead content is properly measured. Every value is backed by a primary source. It is a factual reference, not legal advice. The three numbers used here as examples (0.2, 0.35 and 0.7 percent by mass) are constructed, typical values, not an actual measurement.
Why an old coating lands in the intermediate range
A classic lead-white coating contains double-digit percentages of lead, that was the purpose of the pigment. A value of a few tenths of a percent arises by other routes. Three are typical, and they explain why "a little lead" is not the same as "lead paint".
Lead as a drier (siccative). Oil and alkyd paints harden through oxidative cross-linking, and this process is catalysed by metal soaps, the so-called driers. Lead was one of the classic drier metals, alongside cobalt, manganese and others (Paint & Coatings Industry 2011). As a lead soap, for example lead naphthenate or lead octoate, it is added only at a fraction of a percent of metal relative to the binder; typical metal contents of driers lie in the range of a few tenths of a percent (US Patent 4,631,087). Crucially, a drier is not a pigment. A coating can therefore contain lead from the drier without ever having seen a white lead pigment.
Lead as a minor constituent of a pigment. Not every lead pigment is the dominant white. Red lead (lead tetroxide, Pb3O4, elemental lead fraction around 90 percent) served as a rust-protective primer directly on iron and steel (IARC 2006); beneath several later top coats its lead becomes a minority share of the overall sample. Lead chromate (PbCrO4, lead fraction around 64 percent) was a yellow pigment for chrome-yellow and chrome-green tones (IARC 2006), often only as a tint. Only lead white itself (basic lead carbonate, lead fraction around 80 percent) was the covering white pigment (ColourLex).
The layer effect. A laboratory sample that captures several layers together averages across all of them. A thin, highly leaded layer beneath several lead-free top coats vanishes in the mean: the bulk value can sit at a third of a percent even though a single layer beneath it carries a multiple of that. A mid-range mass percentage can therefore mean two things, "slightly leaded throughout" or "one critical old layer under clean new ones", and the two look identical in the laboratory average (HUD 2012).
For experts (or the expert-curious): elemental lead versus lead compound
A laboratory measures total elemental lead via digestion of the sample. The chemicals-law limits (CLP, see below), by contrast, refer to the concentration of the classified lead compound in the mixture. Since a lead compound contains further atoms besides lead, its mass concentration is always higher than the elemental content: lead white contains around 80 percent lead, lead chromate around 64 percent, red lead around 90 percent (molar-mass calculation from the respective formulae).
This has an uncomfortable consequence for assessment. Comparing an elemental laboratory value against a compound limit is conservative in only one direction. If the elemental value is above the limit, the compound is above it all the more, which is robust. If the elemental value is below the limit, that proves nothing: an elemental value of 0.2 percent corresponds, were the lead present as lead chromate (lead fraction around 64 percent), to more than 0.3 percent compound and thus above the limit. "Elementally just below" can therefore mean "above as a compound".
The most common misconception: 0.3 percent is not a lead-paint definition
The 0.3 percent that keeps coming up in connection with lead coatings is not a threshold above which a coating is called "lead paint". It comes from chemicals law: it is the generic concentration limit at which a mixture must be classified as reproductive toxicant category 1A or 1B (CLP Regulation, Annex I, Table 3.7.2; for category 2 it is 3.0 percent). That is a classification and labelling rule for mixtures, not a statement about an old coating on a wall.
More clearly still: in Austria and in Germany there is no legally binding threshold at all above which an old coating counts generally as "lead paint" or as requiring remediation. Regulation works not through a coating-specific percentage but through three quite different quantities: the material content (percent by mass), the air at the workplace (milligrams per cubic metre) and the blood of the person working (micrograms per decilitre). These three cannot be converted into one another, and that is where most of the confusion comes from.
For experts (or the expert-curious): why there are two lead values (0.3 and 0.03 percent)
Lead is classified EU-wide, in harmonised form, as reproductive toxicant category 1A, and appears in Annex VI of the CLP Regulation with two separate entries, distinguished by particle size (introduced with the 9th adaptation to technical progress, Regulation (EU) 2016/1179, applicable since 1 March 2018).
Lead powder (particle diameter below 1 mm, index 082-013-00-1) carries a specific concentration limit of 0.03 percent for the developmental effect (H360D). Lead massive (particle diameter from 1 mm, index 082-014-00-7) carries no specific limit of its own; here the generic value of 0.3 percent applies. The regulation's recital names both side by side.
What matters is the reach of these values. They concern the classification of lead as a substance. For a paint, that is a mixture with lead compounds such as lead carbonate or lead chromate, the generic value of 0.3 percent applies. The 0.03 percent of the lead-powder entry describes metallic lead powder, not the compound dust produced when a coating is sanded. That a 0.03 percent regime nonetheless applies in practice to this sanding dust follows from the German rules (TRGS 505, see occupational safety), not from this CLP entry. The number 0.03 percent thus exists in both worlds, for related but not identical reasons.
Product law for new paints: the 90-ppm contrast
For paints sold today a lead ban applies in practice. The US consumer product authority sets the limit in 16 CFR 1303.1 at 90 ppm (0.009 percent by mass) of total lead, based on the dried paint film, since 2009. The model law for regulating lead paint issued by UNEP and the WHO recommends the same value, 90 ppm, as a global maximum for new paints. Canada limits consumer paint identically to 90 mg/kg, Switzerland prohibits placing paints on the market from a lead content of 0.01 percent. The classification matters: 90 ppm is an international model and product benchmark, not an EU or Austrian value. In the EU there is no single percentage of this kind; instead the REACH Regulation (Annex XVII, entries 16 and 17) specifically bans the classic lead pigments lead carbonate (lead white) and lead sulphate as a paint constituent.
Worldwide, even this product law is not yet a given: as of 31 March 2023, according to the WHO and UNEP, only 93 countries had legally binding limits for lead in paint, with 19 more in the final stages of legislation.
For an old coating this yardstick is only a contrast, not a measure of assessment. A historic lead coating naturally lies ten to a hundred times above 90 ppm, that was precisely the purpose of the pigment. Even the constructed example value of 0.35 percent lies almost forty times above it. The real question with existing coatings is a different one.
Existing coatings: mass- and area-based definitions, and their absence here
Anyone seeking a robust definition of "lead-containing old coating" will not find one everywhere, but in some countries. Best known is the US definition: the environmental agency EPA (40 CFR 745.103) and the housing agency HUD (24 CFR 35.86) define "lead-based paint" word for word as a coating with at least 1.0 milligram of lead per square centimetre (area-based, usually measured with an X-ray device) or at least 0.5 percent by mass (5,000 mg/kg) of total lead. The "or" matters, and so does the "at least": both criteria are lower bounds, a coating can already be "lead-based paint" via the area criterion even though it is below 0.5 percent by mass.
Other countries draw the line elsewhere. France, within the framework of the "constat de risque d'exposition au plomb" (CREP), which is mandatory on the sale or letting of dwellings built before 1949, defines a lead hazard from 1 milligram per square centimetre (area-based, with a laboratory value of 1.5 mg/g as an alternative; Arrêté of 19 August 2011). Australia lowered the triggering concentration of its management standard AS/NZS 4361.2 in 2017 from 1 percent to 0.1 percent by mass (according to expert information close to the standard's bodies; the standard text itself is not freely available).
The key point: none of these actual existing-coating definitions sits at 0.3 percent. The United States set theirs at 0.5 percent by mass, Australia at 0.1 percent, France area-based. And in Austria as in Germany there is no building-related "lead paint" threshold at all. A targeted search of the relevant bodies of law (limit-value ordinance, health surveillance, chemicals and waste law; in Germany the hazardous-substances rules and the TRGS) finds no such value; a complete negative proof across the entire legal order cannot be produced, but the relevant regulations contain none. The blanket equation "over 0.3 percent, therefore lead paint" is thus doubly wrong: 0.3 percent is, first, a classification limit and not a definition of a coating, and it coincides, second, with not a single one of the existing-coating definitions that actually exist.
How lead content is measured
That the US definition has two criteria, one area-based and one mass-based, is no accident but reflects two quite different measurement methods.
The X-ray fluorescence device (XRF) measures the area loading on site, that is the mass of lead per area in milligrams per square centimetre. Its radiation penetrates the entire layer stack; the reading expressly does not depend on how many lead-free top coats lie above it (HUD 2012). That makes XRF fast and non-destructive, but says nothing about the percentage content of an individual layer.
Laboratory analysis takes the opposite route: from a removed material sample the lead content is determined as a mass fraction, in percent or in milligrams per kilogram (0.5 percent by mass corresponds to 5,000 mg/kg). Evaluated layer by layer, it resolves exactly the ambiguity that a bulk sample creates: it shows whether the lead is thinly distributed everywhere or sits in a single old layer.
The two quantities measure different things and cannot be converted into one another. This is not carelessness but physics: additional lead-free top coats lower the mass fraction in percent but do not change the area loading (HUD 2012). Anyone wanting to know the lead content of a particular coating therefore cannot avoid a professional investigation; it cannot be judged with the naked eye.
For experts (or the expert-curious): why mg/cm² and percent cannot be converted
The area concentration (mg/cm²) is a mass of lead per area and is independent of the thickness of the layer stack. The mass fraction (percent) is a mass of lead per total mass of the sample. The only thing mediating between them is the area weight of the layer, that is mass per area, and that is normally unknown. The HUD guideline puts it unambiguously: one cannot convert percent or ppm into an area concentration unless the total mass per unit area of the sample is known, because adding further lead-free layers changes the mass fraction but not the area concentration (HUD 2012).
As a rough rule of thumb for multi-layer old-building coatings, the same source states in its appendix that 1 mg/cm² corresponds on average to about 1 percent lead. That is expressly a statistical average across typical layer stacks, not a reliable conversion formula for the individual case.
Waste: when lead-containing material becomes hazardous
On removal the question of disposal arises. Here, in Austria, the hazard-relevant property HP 10 (reproductive toxicity) is decisive, and it has a fixed threshold: waste counts as hazardous if it contains 0.3 percent by mass or more of a substance classified with H360 (Waste Catalogue Ordinance 2020, Annex 3, point 10). A 0.03 percent value does not exist in Austrian waste law; it does not appear a single time in the whole of Annex 3. The 0.03 percent sometimes cited comes from the German rules.
Two subtleties are decisive here. First, the value refers to the whole waste, not the coating layer alone: coated solid wood or metal dilutes the lead share, so the overall value usually lies well below the percentage of the pure coating. Pure stripping dust or flaked paint, by contrast, can lie above it. Second, as with the CLP classification, it is the concentration of the lead compound that counts, not the elemental content. In case of doubt, lead-containing removal material is treated as hazardous waste and disposed of via an authorised collector.
Occupational safety: the most important part in practice
It is not the resting coating that is the risk but working on it, and the values here have just been tightened considerably. In Austria a lead air limit of 0.03 mg/m³ has applied since 31 December 2025 as a daily average (short-term value 0.12 mg/m³, inhalable fraction; Limit Value Ordinance as amended by BGBl. II No. 339/2025), reduced from a previous 0.15 mg/m³. The associated biological limit in blood is 30 µg/100 ml (until the end of 2028), then 15 µg/100 ml from 2029; these blood values apply from 9 April 2026. The basis is EU Directive 2024/869, which Austria has adopted.
There is also an old, often forgotten application ban: paints and lacquers with a mass fraction of more than 2 percent lead may not be applied by spraying, except in closed apparatus (Limit Value Ordinance, section 27d paragraph 5). For particularly vulnerable groups, separate rules apply: pregnant women via the general prohibition on harmful substances (Maternity Protection Act, section 4), young people via the prohibition on work with reproductive toxicants (KJBG Ordinance, section 3 paragraph 1 no. 1 lit. g). Lead is not named explicitly in either, but is captured via its classification.
In Germany, TRGS 505 "Lead" (February 2026 edition), as a recognised rule of technology, sets out the protective measures for activities with lead-containing mixtures from 0.3 percent and, for powdery mixtures below 1 mm particle size, from 0.03 percent; the removal of lead-containing surface coatings is expressly covered there (Annex 3). This is why, on sanding, the relevant threshold effectively drops tenfold: the resting coating is measured against the 0.3 percent mark, the fine dust produced by sanding against the 0.03 percent regime.
For practice this means, regardless of the exact content: do not dry-sand, do not burn off, work with low dust, extract at source, wear respiratory protection.
Health: no safe value
The World Health Organization puts it plainly: there is no lead exposure known to be without harmful effects. Even blood lead levels from 3.5 µg/dl can be associated in children with reduced intelligence, behavioural problems and learning difficulties; the US health authority CDC accordingly lowered its reference value in 2021 from 5.0 to 3.5 µg/dl. Children absorb ingested lead up to four to five times as strongly as adults, and during pregnancy lead is released from the bone and reaches the unborn child (WHO). In adults, raised blood pressure, cardiovascular problems and kidney damage are to the fore (WHO).
Decisive for the real risk is the state of the coating: an intact, well-adhering coating is usually not a problem; it becomes critical with flaking paint, on friction surfaces such as windows and doors, and above all on sanding and burning off, when dust is produced (US EPA). The intermediate range is precisely where this distinction counts: harmless at rest, but once it is worked on, every one of these values exceeds the occupational-hygiene thresholds many times over as dust.
All yardsticks compared
The following table places the limits side by side and sorts in the three constructed example values (0.2, 0.35 and 0.7 percent by mass). Important: material mass percent, area loading, air values and blood values are physically different quantities; only mass-based thresholds are directly comparable with a laboratory value in percent. Area values (mg/cm²) and air values appear in the table only for orientation.
| Yardstick | Threshold | 0.2 % | 0.35 % | 0.7 % |
|---|---|---|---|---|
| New paint (US CPSC 16 CFR 1303; WHO/UNEP model law) | 90 ppm (0.009 %) total lead | above (~22x) | above (~39x) | above (~78x) |
| Dust value (CLP lead powder <1 mm; DE TRGS 505) | 0.03 % | above as dust | above as dust | above as dust |
| CLP reproductive toxicity, compact material | 0.3 % (of the compound) | elementally below* | above | above |
| Existing "lead-based paint" USA (EPA/HUD) | 0.5 % total lead (or 1.0 mg/cm²) | below | below | above |
| Existing, Australia (AS/NZS 4361.2) | 0.1 % by mass | above | above | above |
| Waste hazardous (HP 10, in the whole waste) | 0.3 % of the H360 substance | depends on the substrate | depends on the substrate | depends on the substrate |
| "Lead paint" (building, AT and DE) | no statutory threshold | n/a | n/a | n/a |
| Workplace air when worked on | 0.03 mg/m³ (air, not directly comparable) | applies to all in dusty work |
* Elementally below, but since the CLP limit refers to the lead compound, the real value can, depending on the pigment, lie above it (see the foldout above). The area-based values (US 1.0 mg/cm², France 1 mg/cm²) cannot be converted into a mass percentage and are therefore not entered column by column.
The reading in one sentence: all three values are unambiguously lead-containing and exceed the strictest new-paint yardstick many times over; but as "lead-based paint" under the US mass definition only the highest (0.7 %) qualifies, and none of the values meets the much-cited 0.3 percent mark as what it is taken to be. And wherever the value lies exactly: lead becomes dangerous not in the resting coating but as dust on working.
What this means in practice
A lead-containing old coating is no cause for panic and, as a rule, no remediation case as long as it is intact and left in peace. It is the working that becomes critical: sanding, burning off, breaking. Anyone renovating should not dry-sand lead-containing coatings and not burn them off, should work with low dust and, in case of doubt, treat the removal material as hazardous waste. Particularly important is protecting children and pregnant women from paint chips and house dust. And anyone wanting to know whether a particular coating contains lead at all, and how much, has a material sample examined in the laboratory; that is the only way to turn a suspicion into certainty.
Sources
- CLP Regulation (EC) No 1272/2008, Annex I Table 3.7.2 (generic concentration limits for reproductive toxicity, 0.3 and 3.0 percent) and Annex VI (harmonised classification of lead, Repr. 1A). Two lead entries by particle size (lead powder specific limit 0.03 percent; lead massive without a specific limit) introduced by Regulation (EU) 2016/1179: EUR-Lex 32016R1179.
- REACH Regulation (EC) No 1907/2006, Annex XVII, entries 16 (lead carbonates) and 17 (lead sulphates), ban as a paint constituent: EUR-Lex 02006R1907.
- US EPA, 40 CFR 745.103, definition of "lead-based paint" (at least 1.0 mg/cm² or at least 0.5 percent by mass): eCFR 40 CFR 745.103. Identically HUD, 24 CFR 35.86.
- US CPSC, 16 CFR 1303.1, limit of 0.009 percent (90 ppm) for lead in new consumer paint, since 14 August 2009: eCFR 16 CFR 1303.1. UNEP/WHO, "Model Law and Guidance for Regulating Lead Paint" (90 ppm for new paints). Canada, Surface Coating Materials Regulations (SOR/2016-193), 90 mg/kg. Switzerland, ChemRRV (SR 814.81), Annex 2.8, 0.01 percent.
- France, Arrêté of 19 August 2011 on the "constat de risque d'exposition au plomb" (1 mg/cm², laboratory alternative 1.5 mg/g): Légifrance JORFTEXT000024524952. Australia, AS/NZS 4361.2 (triggering concentration since 2017: 0.1 percent by mass).
- WHO and UNEP, "Update on the global status of legal limits for lead in paint" (March 2023): 93 countries with legally binding limits: WHO IRIS.
- HUD, "Guidelines for the Evaluation and Control of Lead-Based Paint Hazards in Housing" (2012), Chapter 7 and Appendix 1 (XRF area loading, laboratory sample in percent by mass, no conversion of mg/cm² to percent): HUD Guidelines.
- Waste Catalogue Ordinance 2020 (BGBl. II No. 409/2020), Annex 3 point 10 (HP 10, threshold 0.3 percent by mass for H360 substances): RIS, AVV Annex 3.
- Limit Value Ordinance 2025 as amended by BGBl. II No. 339/2025 (lead air limit 0.03 mg/m³, short-term value 0.12 mg/m³, in force since 31 December 2025; section 27d paragraph 5 spray ban above 2 %): RIS, BGBl. II 339/2025. Biological limit blood lead 30 or 15 µg/100 ml (health-surveillance ordinance, from 9 April 2026). EU Directive 2024/869. Maternity Protection Act section 4; KJBG Ordinance section 3 paragraph 1 no. 1 lit. g.
- TRGS 505 "Lead" (February 2026 edition), trigger thresholds 0.3 and 0.03 percent by mass, surface coatings (Annex 3): official state copy, Gewerbeaufsicht Baden-Württemberg.
- WHO, "Lead poisoning" (no safe exposure value; blood lead from 3.5 µg/dl; children absorb up to 4 to 5 times as much; effects in adults): who.int. CDC, reference value 3.5 µg/dl (2021): CDC MMWR 2021. US EPA, "Protect Your Family from Sources of Lead" (intact coating usually not critical): epa.gov.
- Driers and lead pigments: Paint & Coatings Industry, "Driers for Alkyd Coatings" (2011); IARC Monographs Vol. 87, "Inorganic and Organic Lead Compounds" (2006, red lead as rust protection, lead chromate as yellow pigment); ColourLex, "Lead White".
Technical reference, not legal advice. Where else lead hides in old buildings, in pipes, dust and coatings, and the history behind it, is covered in our article on lead in the building.
Questions on the topic? Free Initial Consultation.