Send us a text (https://www.buzzsprout.com/twilio/text_messages/2264976/open_sms)

Ever wondered if that tiny spot of mold in your bathroom corner actually matters? A study from France just answered this question with a resounding yes – and the findings should make us all reconsider how we think about household mould.

Mouldy area size and asthma symptom score and control in adults: the 

CONSTANCES cohort

Drawing from an impressive pool of over 28,000 adults, researchers have established something both alarming and actionable: even the smallest visible mold growth significantly increases asthma risk in adults. This isn't just about massive infestations; the study reveals a clear "ladder of risk" where each step up in mold coverage – from mere spots to larger areas – progressively worsens asthma symptoms and control. People living with any visible mold were approximately 40% more likely to have current asthma and poorer symptom control.

What makes this research particularly valuable is its practical approach. Rather than treating mold as a simple yes/no question, researchers asked participants to estimate contaminated areas using everyday references (like comparing 0.2 square meters to three sheets of paper). They found that mould in bedrooms and living rooms – where we spend most of our time – had the strongest health impacts. The message is clear: mold isn't just a maintenance or aesthetic issue; it's a health hazard from the moment it appears, and its impact scales with its size.

For housing providers, healthcare professionals, and anyone who lives in a building (which is all of us!), these findings transform how we should approach even minor mold growth. That little patch in the corner isn't just unsightly – it's actively affecting respiratory health. 

Mouldy area size and asthma symptom score and control in adults: the 

CONSTANCES cohort (https://doi.org/10.1016/j.envres.2025.122254)

Support the show (https://www.buymeacoffee.com/Airqualitymatters)

Check out the Air Quality Matters (https://www.airqualitymatters.net/podcast) website for more information, updates and more. And the YouTube Channel (https://www.youtube.com/@airqualitymatters-SimonJones/featured)

The Air Quality Matters Podcast is brought to you in partnership with.

Eurovent (https://www.eurovent.eu/) Farmwood (https://farmwood.co.uk/) Aereco (https://www.aereco.co.uk/) Aico (https://www.aico.co.uk/) Ultra Protect (https://www.ultra-protect.co.uk/air-quality-matters) Zehnder Group (https://www.zehndergroup.com/?utm_source=SoMe&utm_medium=link&utm_campaign=AQM_p%20odcast)

The One Take Podcast is brought to you in partnership with.

SafeTraces (https://www.safetraces.com/) & InBiot (https://en.inbiot.es/?utm_source=airqualitymatters&utm_medium=podcast)

All great companies that share the podcast's passion for better air quality in the built environment. Supporting them helps support the show.