Other home-air emission products (case-by-case, inhalation prioritized) — HMTc Standard

How every number on this page is set

CATEGORY-SPECIFIC METHOD NOTES. (1) INHALATION IS THE DEFINING PATHWAY AND THE PANEL IS STILL A CONTENT SCREEN. Every row here is used by aerosolisation, evaporation or combustion and the exposure of concern is respiratory. A limit expressed per kilogram of product is NOT an inhalation exposure limit and is not presented as one. HMTc publishes no emission-rate limit, no per-actuation dose limit and no indoor-air concentration limit for this category, because no credible sovereign government sets one for any of these product forms. What the panel governs is the content of the material that is put into the air, plus the components in the emission path. No occupational exposure limit and no ambient- or indoor-air guideline is converted into a product ceiling anywhere in this category. (2) THE READ-ACROSS IS TAKEN ON THE ROUTE AXIS, AND IT IS DISCLOSED. No government anywhere sets a heavy-metal content maximum for an air freshener, plug-in evaporator, puff releaser, candle body, wax melt, oil or nebula diffuser, gel or reed diffuser, incense stick, potpourri, vacuum fragrance additive or fragrance refill. The nearest applicable sovereign cells are the route-scoped content maxima that US state cannabis regulators set for products administered by INHALATION, and they are nearest not by matrix but by route and by basis. Colorado's 2022 table and Maryland's Technical Authority Rev. 6.0 each publish a route LADDER over the same underlying matrices - inhalation strictest, then oral, then cutaneous - which demonstrates that the value is a function of the route of administration rather than of the source matrix's chemistry. Colorado scopes its strictest row in the instrument's own words to "inhaled product or audited product administered by metered-dose nasal spray". Maryland's route gap is the sharpest evidence available: its inhalation-route total-chromium value is 600 ug/kg while its oral and cutaneous values for the same products are 1,100,000 ug/kg, a factor of about 1,833. Every such cell is published as `read-across` with the source instrument named, never as `regulatory-alignment`. (3) WHAT THE READ-ACROSS DOES NOT DO. It does not re-derive an exposure assessment. Consumption mass differs between a cannabis product and a candle, and HMTc does not adjust the sovereign value up or down to account for that: Method v2.0 forbids an occurrence-derived, percentile, feasibility or precautionary adjustment in either direction. The adopted values are three to four orders of magnitude stricter than every article-content instrument that actually binds these products (RoHS lead at 1,000,000 ug/kg of homogeneous material; the candlewick-core prohibition threshold at 600,000 ug/kg of wick-core metal; REACH cadmium in polymers at 100,000 ug/kg), so the read-across tightens the applicable regulatory position rather than relaxing it. (4) THE CANDLEWICK PROHIBITION IS A PROHIBITION, NOT A CEILING. 16 CFR 1500.17(a)(13) declares candles with lead-cored wicks, and such wicks in themselves, to be banned hazardous substances, using 0.06 percent lead by weight of the metal in the wick core as the definitional threshold. Australia's Customs (Prohibited Imports) Regulations 1956 mirror it. That threshold is measured on the metal of the wick core, in a basis that is not any row's basis here, and it is NOT published as this category's lead ceiling: publishing 600,000 ug/kg against a scented candle would misrepresent a prohibition as a permission. It is carried on the scented-candles row as an independent pass/fail component hard stop instead. The wickless wax-melt row does NOT carry it, because a melt has no wick of its own and the heat source is a separate product; that limitation is stated rather than papered over. (5) COMBUSTION AND EVAPORATION CONCENTRATE, THEY DO NOT DESTROY. Burning a candle or an incense stick, and heating an oil reservoir, remove volatile mass and leave the non-volatile metal behind, partitioned between the emitted soot and aerosol and the residual wax, ash and reservoir film. A content screen on the unburnt article is therefore a LOWER BOUND on the metal available to the emission path, not a measure of what is emitted. Combustion and heated rows carry mandatory post-burn residue, ash or reservoir-film analysis in their reference methods for exactly that reason, and hexavalent chromium is speciated on the residue as well as on the article because flame and glow temperatures oxidise trivalent chromium. (6) FIVE PANEL CELLS HAVE NO SOVEREIGN NUMBER ANYWHERE AND ARE HELD UNDER CONTROL. No inhaled-product instrument in any jurisdiction publishes nickel, tin, aluminium, inorganic arsenic or hexavalent chromium. Each of those cells is a control with a named reference method, a component-level sampling plan and an escalation rule. None is declared not-material, because each is genuinely material in at least part of this category, and none is given an invented ceiling. (7) SPECIES NEVER REPLACE TOTALS. Inorganic arsenic does not satisfy total arsenic, methylmercury does not satisfy total mercury, and hexavalent chromium does not satisfy total chromium. Total chromium is published as a SCREEN and is excluded from the firm-limit count; hexavalent chromium carries a zero-tolerance disposition rather than a number. (8) METHYLMERCURY IS SPLIT BY FORMULATION CLASS, NOT ASSUMED. Twelve rows whose emitting material is a manufactured non-marine formulation carry a not-material determination bounded by total mercury. Three rows do not: incense sticks and cones, potpourri and sachets, and the residual row, because those admit marine-derived and wild-harvested animal material (ambergris and marine-animal perfumery fixatives, dried seaweed, shell and coral decorative elements, undetermined natural inputs) and a categorical no-methylation-pathway claim would be false for part of the row. Those three are controls. (9) REGISTER GAPS ARE DISCLOSED, NOT FILLED. The Australian candle-wick lead rows are present on the register (au_customs_1956_pb_candles_wicks_0_06pct, au_customs_1956_pb_candle_wicks_0_06pct) but jurisdiction AU sits outside both the default credible set and this category's widening, so they are disclosed in prose and not named as anchors. Whether the Colorado and California cannabis instruments publish nickel, tin or aluminium values that this register simply lacks is unverified and is recorded as a register gap rather than assumed either way. The RIVM air-freshener product-type list and the EU CLP Regulation, both named as regulatory anchors in the taxonomy entry for this category, set no heavy-metal content maxima: RIVM supplies an exposure-factor framework and CLP classifies hazards, so neither yields a number and neither is on the register. Nothing in this config is written from memory; every number resolves to a named register row.

Master Limit Table

All values in ppb (µg/kg), as-sold basis. 4 of 11 analytes carry a firm ceiling; the remainder are governed by mandatory control or reflex-speciation screening with no standalone number, itemised in the derivation below. A brand meeting every firm value on a like-for-like basis, and passing every control, qualifies for the mark.

Tier 1 (Pb, iAs, Hg, MeHg, Cd) are zero-tolerance toxics with no established safe threshold. Tier 2 (tAs, Cr-VI, Ni, Sn, Al, Cr) carry a 150% transitional allowance under the program’s Status A–E framework.

Derivation — every government’s number, side by side

The full derivation for Other home-air emission products (case-by-case, inhalation prioritized). Each row lists every government maximum level in force worldwide, converted to the as-sold basis; the HMTc limit is the strictest of them, and the last column names which sovereign law binds. A blank cell means that government sets no limit for this analyte in this product.

All values µg/kg (ppb), as-sold basis. ² no government regulates this analyte for this exact product form: the value is a disclosed read-across from the nearest applicable government maximum, and the derivation names the instrument it comes from. It is never taken from occurrence data. After publication the standards ratchet may tighten it, using certified-lot results only. ³ not material in this matrix: controlled by reflex speciation or packaging control, not a standalone number. &sup4; no sovereign maximum exists for this analyte in this product, but a credible exposure pathway does — it is screened on every lot under ALARA against the tightest analogous reference, not assigned an invented number.

Cite this standard

Pendergrass, K. “Other home-air emission products (case-by-case, inhalation prioritized).” In Heavy Metal Tested & Certified (HMTc) Home Air and Inhalation-Adjacent Products standard, version 1.0. Institute of Contaminant Standards (ICS), 2026. DOI: registration pending.

The literature baseline for every analyte is maintained independently at the Heavy Metal Index. This certification standard applies those findings; the two are kept editorially separate by design.