What’s the Point of Measuring Indoor Air Quality (IAQ)?

“Indoor air pollution is important because over 80% of a typical adult day is spent indoors. Despite this, we have much less knowledge about the sources and people’s exposure to indoor air pollution, and a less well-developed plan for reducing it.”— Chief Medical Officer’s Annual Report 2022, Air Pollution]

Indoor air quality is becoming a critical factor for health. While some pollutants, like particulate matter (PM) and nitrogen oxides (NOx), can enter buildings from outside, many are generated indoors.

Volatile organic compounds (VOCs) from cleaning products, carbon monoxide from poorly ventilated appliances, and even mould spores are just a few examples. Reducing emissions of these pollutants, identifying new ones that pose health risks, and optimizing ventilation are all essential.

But striking a balance is a challenge—especially in buildings where maintaining warmth in winter, cooling in summer, and minimizing energy use are all competing priorities.

The right approach will vary depending on the building type, season, heating types, income, ventilation and occupancy.

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The Challenge: Turning Insight into Action

Measuring indoor air quality (IAQ) is easier than ever. We have monitors that detect particulates, VOCs, humidity, CO₂, and more—giving us insights into what we're breathing at home, at work, and everywhere in between.

But here's the real challenge:

Once you know the air is bad… what do you actually do about it? The problem isn't just detection—it's triggering action. And that’s where things get complicated. 

We worked with Green Doctors Yorkshire and Leeds City Council Health Protection team to answer this vital question.

Let’s say you’ve identified high levels of pollutants in someone’s home. Now you’re faced with real-life questions that aren't so easy to solve:

• How do you get someone to stop burning candles or using plug-in air fresheners that are clearly spiking VOC levels?

• How do you convince a landlord to fast-track a proper ventilation strategy rather than just opening a window?

• How do you persuade someone that getting their oven professionally cleaned could help with lingering odours and airborne particles?

• How do you stop—or at least reduce—reliance on a wood-burning stove in winter?

• And how do you get a contractor to properly remove mould instead of wiping it and calling it a day?

Knowledge is great, but convincing someone to take meaningful action? That’s the real hurdle. Data on its own doesn’t always motivate change. In fact, in some cases, it can overwhelm or alienate the very people you're trying to help.

That’s the problem we’ve been focused on solving:How do you turn indoor air quality insights into real-world decisions and behaviour change?

Understanding the Invisible: PM2.5 and VOCs

Indoor air quality is affected by a range of pollutants, but two of the most important (and commonly misunderstood) are PM2.5 and VOCs.

PM2.5 refers to fine particulate matter—tiny airborne particles that are 2.5 microns or smaller in diameter. These are small enough to lodge deep in the lungs. In our study, PM2.5 was especially important because mould spores often fall within this range.

Other common sources of PM2.5 include cooking, wood burners, smoking, candles, and poorly ventilated appliances—all of which can significantly raise exposure indoors.

Then there are VOCs, or Volatile Organic Compounds—a wide range of chemicals that easily evaporate into the air. They come from everyday products like air fresheners, cleaning sprays, paints, soft furnishings, and cosmetics. When concentrated indoors, VOCs can cause irritation, headaches, or more serious health effects over time.

5-Minute Sampling: A New Standard in Air Quality Monitoring

To help people understand their exposure—and act on it—we developed a set of indoor air quality sensors specifically designed to measure both PM2.5 and VOCs in real-time.

Typical air quality monitors take snapshots, or maybe hourly averages. We knew that wasn’t enough.

We engineered our devices to send air quality data to our cloud-based analytics platform every 5 minutes. This level of detail creates a dynamic, high-resolution picture of what’s really happening in a home or building—something that simply hasn’t been done at this scale before.

Why does this matter?

Because air quality isn’t static. It spikes when someone lights a candle, opens the oven, sprays an air freshener, or starts cooking without ventilation. It drops again once windows are opened or fans are turned on. Without frequent data points, you miss those patterns—and the chance to change behaviour.

By capturing pollution events in near real-time, we can:

• Identify specific causes of poor air quality

• Pinpoint the exact time and frequency of exposure

• Provide evidence-based recommendations tailored to that home

• Detect recurring problems that would otherwise go unnoticed

This approach doesn’t just monitor—it helps explain why something is happening, and what to do about it.

Visualising the Risk: What Does Good and Bad Air Quality Look Like?

Understanding PM2.5 and VOCs is one thing—seeing how they’re measured and what levels are considered safe is another. The visuals below show the scales the World Health Organisation (WHO) uses when analysing indoor air quality.

PM2.5: Fine Particles Including Mould Fragments

The World Health Organisation (WHO) recommends a 24-hour average limit of 15 µg/m³ for PM2.5.

Many homes we studied regularly exceeded this—especially those with mould issues, poor ventilation, or regular use of wood burners, cooking without extraction, or dusty environments.

VOC Index: Everyday Chemicals You Can’t See

Although there is no official WHO limit for total VOCs, many international guidelines and sensor manufacturers consider:

• Below 100 – Excellent

• 100–200 – Acceptable

• 200+ – Potentially harmful or irritating

Our 5-minute data sampling revealed that VOC spikes often go unnoticed, triggered by things like cleaning sprays, air fresheners, or scented candles—even when used briefly.

What Happens Next: From Data to Action

This is where the power of detailed, real-time air quality monitoring comes to life. Below are real examples of how PM2.5 and VOC insights helped residents, landlords, and housing teams take meaningful action:

Case Study 1: Cold Kitchen, Mould, and a Dirty Oven

A couple were living in a home where the kitchen regularly dropped to as low as 12°C. They had visible mould on the walls, and every time they used the oven, there was a strong, lingering smell.

Air quality readings showed high PM2.5 levels, and VOC spikes that mirrored oven use. Once the couple turned up the heating, had the mould professionally removed, and got the oven cleaned back to near-new condition, the results were immediate.

• PM2.5 and VOC levels dropped significantly

• The residents experienced better comfort and air quality

• The landlord protected the property from further damage

Case Study 2: Smoking, Candles, and No Fresh Air

In a retirement village home, one resident lived in a single-room flat with no partitions. There was no mould, but PM2.5 and VOC levels were consistently high due to indoor smoking and regular use of scented candles to mask the smell.

The heating—part of a communal system—was very high and couldn’t be individually controlled, and our date showed the resident rarely opened windows.

We took a small-steps approach:

• Encouraged him to stop using candles

• Suggested opening windows regularly, even for short periods

• Collaborated with the Housing Association to explore options for better heating control

The smoking remains a challenge, but progress is being made. Even small changes showed measurable improvement in air quality.

Case Study 3: Asthma, Mould, and a Council-Led Response

A mother and her 5-year-old child with asthma were living in a private rented home where mould was visibly present and PM2.5 levels were dangerously high. The child required respiratory support, and the conditions were clearly affecting their health.

The issue was picked up by the council’s environmental health team, who brought in a charitable organisation to help with professional mould cleanup.

A HEPA air filter was installed, and early results are promising:

• PM2.5 levels dropped

• Discussions are ongoing with the landlord

• There’s still work to be done, but the outcome is looking positive

Case Study 4: Rethinking the Wood Burner

A young couple living in a cosy home loved their wood-burning stove—but didn’t realise just how much it was impacting their air quality.

Our sensors clearly showed the dramatic rise in PM2.5 levels when the fire was lit, and how long those high levels lingered.

By showing them the data side-by-side with WHO guidelines, they began rethinking when and how they used the stove:

• Limiting its use on mild days

• Improving ventilation during and after use

A small behavioural change led to a big drop in exposure.

Final Thoughts

Air quality monitoring isn't just about numbers on a screen—it's about protecting health, improving comfort, and giving people the tools to make better choices. But insight alone isn’t enough. You need a system that turns data into understanding, and people to turn understanding into action.

We’re helping homes, landlords, and councils do something they’ve never been able to do before: truly see the air—and change it.

Special thanks to Green Doctors, Leeds City Council Health Protection team for working with us on this project.  We are now working together to create a personalised, data driven report and guidance that anyone can understand.

Talk to us to see if we can help you develop better strategies for indoor health and healthy homes. dampsmart.co/contact

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