Passive Purple Certified to the Finnish M1 Emission Class
Healthy indoor air is no longer a nice-to-have — it's a design requirement. Passive Purple is certified to the Finnish M1 emission class, the top low-emission rating in one of Europe's most respected building-materials schemes. Alongside its French A+ rating, this gives specifiers a second, fully independent credential confirming Passive Purple as a genuinely low-emission product.
What is the M1 emission class? 🛡️
M1 comes from the Finnish RTS "Emission Classification of Building Materials", run by Rakennustieto Oy / RTS in Finland. It's a voluntary but highly regarded scheme that rates how much a construction product emits into indoor air, and how much odour it produces.
Materials are placed into one of three classes:
- M1 — the best class, for the lowest emissions and odour
- M2 — intermediate emissions
- M3 — the highest emissions of the classified bands
M1 is the class specifiers look for. It is widely referenced in healthy-building programmes and appears frequently in international green-building specifications as a benchmark for low-emitting interior products.
Passive Purple's M1 classification
Passive Purple has been classified Emission Class M1 by Rakennustieto Oy / RTS under reference 3720, valid until 01.09.2027. The classification covers both Passive Purple and Passive Purple Brush.
The classification is underpinned by laboratory testing carried out by VTT, Finland's national research organisation, to a suite of recognised emissions standards:
- EN ISO 16000-9 — emissions testing using a chamber method
- EN ISO 16000-6 — determination of VOCs in indoor air
- EN 717-1 — formaldehyde emissions by the chamber method
- EN ISO 16000-28 — determination of odour from building products
The testing found Passive Purple to be free from VOCs, TVOC, carcinogens, ammonia and formaldehyde — the substances that matter most when assessing what a coating releases into occupied spaces.
Why M1 matters 🔒
An airtightness and vapour-control membrane is applied across large internal surfaces and stays in the building for its whole service life. What it emits into the air is therefore a long-term consideration for occupant health and comfort. An M1 classification tells you, on independent authority, that those emissions are as low as the scheme recognises.
Passive Purple is water-based with no organic solvents, which is the reason it performs so well against these standards. The M1 result puts a rigorous, third-party seal on that formulation — tested by VTT and classified by RTS, entirely independently of the manufacturer.
Two credentials, one strong story ☀️
M1 doesn't stand alone. It sits alongside Passive Purple's French A+ rating, the cleanest band in France's mandatory emissions labelling scheme. Two separate, internationally recognised schemes — one Finnish, one French — both reaching the same conclusion: Passive Purple is a low-emission product suitable for the most air-quality-sensitive environments.
For specifiers, that combination is powerful. Whether a project references European labelling, a green-building rating system, or simply a client's own healthy-building expectations, Passive Purple carries recognised evidence to satisfy it. Schools, healthcare buildings, homes and Passivhaus projects all benefit from a membrane that delivers airtightness and vapour control without compromising indoor air.
Specify with confidence
Low-emission credentials like M1 are increasingly written into project requirements, and Passive Purple already meets the top class. It's one more reason to treat it as the airtight, vapour-control layer of choice for healthy, high-performance buildings.
See the underlying certificates and the rest of Passive Purple's independent testing. See all Passive Purple test data & certifications, or explore the product in full at Passive Purple.