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uHoo Proprietary Health Index · Research-backed

Mold grows in the dark. Discover what causes it.

Humidity, temperature, and stagnant air create the environment mold needs. The uHoo Mold Index tracks those conditions continuously and tells you your risk level in real time, so you can act while the fix is still a window and not a contractor.

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✓ Built on published science ✓ Real-time detection and alerts ✓ Covers 9 parameters including PM2.5, NO₂, and ozone
Mold Index · Live reading
2
Low risk · No action needed
Humidity54%
Temperature22°C
VOCsModerate
Conditions unfavourable for mold
10
Point scoring scale
Daily
Index recalculation
3
Key parameters driving the score
0
Manual testing required
What the Mold Index measures

All the data you need to prevent mold growth.

Mold thrives in damp, humid environments where air does not circulate. The uHoo Mold Index uses your live sensor readings to calculate a daily risk score from 1 to 10. The higher the score, the higher the probability that mold conditions exist in that space.

Research has established a clear link between indoor air parameters and mold formation. High humidity, poor ventilation, and temperature swings create conditions where mold spores germinate and spread. Often for weeks before anything becomes visible.

Unlike periodic spot checks, the Mold Index tracks how conditions evolve continuously. A room that looked fine last week may have developed a moisture problem overnight. The index catches it early, when opening a window is still the solution.

What the Mold Index measures
Scoring system

One number. Four levels of risk. Always clear.

Every score maps to a specific risk level with plain-language guidance on what it means for your space and exactly what to do about it.

1-3
Low
Mold growth is unlikely. No action needed.
Your indoor conditions are currently unfavourable for mold growth and survival. Continue monitoring and uHoo will alert you if conditions begin to shift.
Keep humidity below 60%Maintain regular ventilationNo immediate action required
4-6
Moderate
Conditions are becoming favourable. Act now before the index climbs further.
Mold may be present in small quantities only detectable under a microscope. Improve ventilation and bring humidity back into the safe range before conditions get worse.
Increase ventilationCheck for hidden moisture sourcesDehumidify if above 65% RH
7-8
High
Mold is likely present and may already be visible. Urgent action needed.
At this level mold growth is probable. Occupants with respiratory conditions or allergies may already be experiencing symptoms. Inspect wall junctions, window frames, and cavity spaces now.
Ventilate immediatelyInspect walls and ceilingsApply anti-mold treatmentTarget humidity below 50%
9-10
Critical
Mold is highly likely and visible. Remediation required.
Conditions strongly support active mold growth that is likely visible to the naked eye. This poses a real health and safety risk to most occupants. Professional assessment should be arranged as soon as possible.
Professional inspection recommendedLimit time in affected spacesAddress moisture source urgently
What drives your score

Three parameters. One complete risk picture.

The Mold Index is calculated continuously from your live uHoo sensor data. These are the three factors that matter most and the thresholds where risk begins to build.

Relative humidity logo
Relative Humidity
The single biggest driver of mold risk. Mold spores begin to germinate when relative humidity sustains above 60% for extended periods. Bathrooms, basements, and poorly ventilated kitchens are the most common early sites.
Risk zone: above 60% RH sustained
Temperature logo
Temperature
Most mold species grow most aggressively between 15°C and 30°C, which overlaps almost exactly with comfortable living conditions. Cold surfaces in warm rooms create condensation that accelerates growth at wall junctions and window frames.
Risk zone: 15°C to 30°C combined with high humidity
Air circulation logo
Air Circulation
Stagnant air lets moisture concentrate in corners and cavities. Even when overall humidity is moderate, poor airflow means localised pockets can reach mold-growth conditions while the rest of the room appears fine.
Risk zone: consistently still air in enclosed spaces
For families
For families

Children breathe faster and are five times more vulnerable to airborne mold than adults.

Their immune systems are still developing and they take in more air relative to body weight. A nursery that looks clean and smells fine may already have mold conditions building inside the walls. The Mold Index gives parents early warning. When the fix is opening a window, not calling a remediation company.

✓Tracks overnight humidity in closed nurseries and bedrooms
✓Alerts you when conditions shift before mold becomes visible
✓Available on Guard and Command home plans
For buildings and businesses

Most mold damage is found after the remediation bill, not before it.

Facilities teams using uHoo Aura can monitor mold risk across every floor and every zone from a single dashboard. The Mold Index flags high-risk areas before occupants report symptoms, giving you the window to act at maintenance cost rather than remediation cost.

✓Monitor risk across unlimited rooms, floors, and locations
✓API access for BMS and facilities management integration
✓Supports WELL and Green Mark certification requirements
Explore uHoo Aura for businesses ->
For buildings and businesses
The research behind the index

Built on data. Validated by science.

The uHoo Mold Index is not an estimate. It is a risk model built on peer-reviewed research into indoor air quality and mold formation. The full methodology is published and available to read.

White paper · January 2025
A Comprehensive Approach for Mitigating Mold's Adverse Impact via Indoor Environmental Quality Monitoring
uHoo Research · 28 pages · PDF
This paper details the methodology behind the uHoo Mold Index, covering the parameter relationships, scoring model, validation studies, and real-world case data that underpin every risk score your device produces.
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Common questions

What people ask about the Mold Index.

The Mold Index is available on Guard, Command, and uHoo Aura. For home users, Guard and Command both include all four health indices: Mold, Virus, Influenza, and Pollen. For businesses, the Mold Index is part of the uHoo Aura suite. If you are on Sense and want access to the indices, you can upgrade to Guard from your account dashboard at any time.
The Mold Index is recalculated daily using your live sensor readings and the proprietary risk model developed by uHoo's research team. Your score reflects the conditions in your specific space, not a generic regional estimate. As your indoor environment changes, your score adjusts accordingly.
A low score means current conditions are unfavourable for new mold growth. It does not confirm whether pre-existing mold from a previous period is still present. If you have a persistent musty smell despite a low index score, a professional inspection is worth arranging, as existing colonies can persist even after conditions improve.
Yes. Each uHoo device generates its own Mold Index score for the room it monitors. A kitchen and a bedroom will often have very different scores, and that room-level granularity is exactly what makes the index useful. Guard and Command users can compare scores across every room they monitor from the same dashboard view.
uHoo data, including the parameters that power the Mold Index, is accepted directly by WELL, LEED, and Green Mark assessors. The continuous humidity, temperature, and VOC monitoring that drives the Mold Index also satisfies Indoor Environmental Quality requirements under these frameworks. Visit our certifications page for details on specific credits.
The full index suite

Mold is one of four things the index watches for you.

Guard, Command, and uHoo Aura include three other proprietary health indices, each tracking a different invisible indoor air risk.

Virus Index logo
Virus Index
Tracks indoor conditions that allow airborne viruses to survive and spread. Rises when temperature and humidity favour viral persistence, giving you a clear signal to ventilate before anyone gets sick.
Learn about the Virus Index ->
Influenza Index logo
Influenza Index
Specific to seasonal flu transmission risk. Cold months create indoor air conditions that accelerate influenza spread. Know when risk is highest so you can act at the right moment.
Learn about the Influenza Index ->
Pollen Index logo
Pollen Index
Outdoor forecasts only tell half the story. The Pollen Index tracks how pollen infiltrates your indoor air and when your home's conditions intensify its impact on allergy and asthma sufferers.
Learn about the Pollen Index ->
Available on Guard, Command, and uHoo Aura
Available on Guard, Command, and uHoo Aura

See the conditions that let mold grow before it does.

All four health indices updated daily from your live sensor data. Mold, Virus, Influenza, and Pollen. For home or for business.

See home plans uHoo Aura for business ->
Guard · Command · uHoo Aura