Fan On! Why Your Home’s Air Quality Matters – Expert Q&A Blog

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Posted on Friday 27 June 2025

Each day, we breathe in about 11,000 litres of air. We spend 80% of our time indoors, which means most of our breathing during our lifetimes happens inside.

Image shows curved computer screen with webinar attendees on the screen

Whether we are cooking at home, working in an office, studying at school, or sleeping at night, the indoor air environment is vital for our wellbeing. However, awareness of indoor air quality (IAQ) remains significantly lower than our understanding of outdoor pollution.

As part of London Climate Action Week (LCAW) 2025, the INGENIOUS project, led by the University of York, hosted a public webinar on 23 June titled "Fan On, Pan On! Why Your Home's Air Quality Matters." The event aimed to share key findings from the UKRI-funded INGENIOUS project. INGENIOUS ( Understanding the Sources, Transformations and Fates of Indoor Air Pollutants) is a comprehensive research initiative investigating indoor air pollution across more than 300 homes in Bradford, UK. Held just days after UK Clean Air Day, the event aimed to enhance public understanding of its research findings and recommendations and to bring together a panel of experts to discuss actionable strategies for improving IAQ. The INGENIOUS project aims to understand the sources, transformations, and effects of indoor air pollutants. Through air sampling, modelling, and behavioural research, the project investigates these unknowns and delivers beneficial interventions to limit exposure.

Webinar speakers include Prof Nicola Carslaw and Prof Nicholas Pleace, both from the University of York; Prof Catherine Noakes and Dr Chris Brown, both from the University of Leeds—Chris is also affiliated with the Born in Bradford organisation, a member of the INGENIOUS consortium; and Dr Ali Body from Global Action Plan.

We have compiled some of the most frequently asked questions and key insights from the webinar into this Q&A format to help you better understand and improve your home's air quality.

Why is indoor air quality such a big deal?

Harriett Richardson from the National Centre for Atmospheric Science, as the event facilitator, opened the webinar by reminding participants that IAQ often goes unnoticed, even though people spend as much as 80% of their time indoors. " But what’s in the air we breathe? How does it affect our health, and what can we do about it?" she asked.

Harriett said that research, including that from INGENIOUS, has uncovered critical insights into how pollutants form indoors, how our everyday behaviours affect air quality, and what we can do to make our spaces healthier and more sustainable, especially as we move towards more energy-efficient and airtight homes.

What did the INGENIOUS study uncover about real-life UK homes?

The INGENIOUS project employs a variety of methods to gather comprehensive data. These include laboratory experiments, real home surveys, mobile measurements, and modelling. The testing facilities at York include laboratories, monitors and a van, allowing for extensive measurements of air pollutants both indoors and outdoors.

An INGENIOUS survey , working in collaboration with Born In Bradford, covered 310 homes in Bradford, revealed that indoor particulate matter 2.5 (PM2.5) concentrations, reflected outdoor PM2.5 levels when there was no occupant activity indoors. Nicola Carslaw describes PM2.5 as exceptionally small particulate matter, with a diameter less than 2.5 microns, making it significantly smaller than sand or a human hair. Due to its minute size, it is easily inhaled and can penetrate deep into the respiratory system, posing a potential health risk and serving as a key indicator of harmful air pollution.However, human behaviour, such as cooking, was a primary factor driving the much higher concentrations that were often observed. Interestingly, the variability in indoor pollutant concentrations was greater between different homes than between seasons, highlighting the significance of individual behaviour and housing conditions.

What are the primary sources of indoor air pollution?

Professor Nic Carslaw presented findings from the INGENIOUS project, emphasising that everyday activities are significant contributors and can have significant impacts on indoor air quality. INGENIOUS experiments showed that cooking is a notable source of indoor air pollutants. The research highlights that emissions vary between different meals. While emissions of alcohols are the most common result of cooking, other compounds like aldehydes, alkanes, and terpenes are also released, with their specific concentrations depending on the ingredients and cooking process. This data can be used to inform UK emissions inventories. In her presentation on how to improve IAQ, Nic noted that "It's important to ventilate spaces properly, even for everyday activities in a house. So, use extractor fans when cooking and showering, or open windows when cleaning. Also, try to ventilate bedrooms when sleeping."

Are there any rapid ways to improve indoor air quality?

Good ventilation is essential for healthy indoor environments. Poorer households are more likely to be in poor-quality as well as overcrowded housing. There is a need for tailored ventilation strategies for different types of spaces, from homes to schools and other public buildings. Ali Body noted that while ventilation is essential, it is not enough on its own; removing pollution sources, such as gas cookers, is key, and policy changes are needed to support cleaner, healthier homes, especially in poor communities. Reinforcing Ali Body’s call for policy change, Dr Chris Brown also stresses the need for targeted, evidence-based interventions to address poor air quality and its broader social impacts in disadvantaged communities. He emphasised that greater inequality often leads to worse IAQ, which is associated with inadequate housing, which negatively affects children's health, education, and life chances on multiple levels. He highlighted the need for targeted, evidence-based policies to support the low-income and poor households.

To reduce indoor air pollution, the panel recommended switching from spray-based products to alternatives, such as cream cleaners and roll-on deodorants. These emit fewer chemicals into the air, making them a healthier choice for indoor environments.

Additionally, ensuring proper ventilation during activities like cooking and showering is crucial. Using cooker hoods and shower extractor fans helps remove airborne pollutants. If these are not available, opening windows during and after these activities can be effective. Small changes in cooking habits, such as using the back ring on a stove for better extractor efficiency or boiling and steaming food instead of frying, can also lower particle emissions.

Professor Catherine Noakes observed that maintaining a clean yet chemical-safe home is important. “Regular vacuuming helps remove dust and allergens, improving indoor air quality. However, it is essential to avoid overusing spray cleaners, which can introduce unnecessary chemicals into the environment,” she explained. Instead, use cleaning products more selectively and thoughtfully to minimise exposure. While tools like air fryers are better than open frying, they are not completely pollutant-free, so being mindful of their use and turning fans on or opening windows is also advised. Additionally, we must pay special attention to ventilation in high-occupancy households.

What’s the future for improved indoor air quality in the UK?

We must consider IAQ in relevant policy and public health strategies. Ignoring indoor environments is no longer an option. The INGENIOUS team proposed a series of strategic interventions:

Standardise testing for cleaning products and furnishings under realistic indoor conditions.
Encourage innovation in low-emission materials and effective ventilation technologies.
Establish national guidelines to strengthen Indoor Air Quality (IAQ) standards for public and private spaces.
Introduce a "traffic light system" for high-emission products to inform consumer choice.
Consider bespoke ventilation strategies for vulnerable populations (e.g., hospitals, schools, care homes).
Consider additional ventilation strategies for high-emitting activities and products (e.g., restaurants and beauty salons).

As the UK accelerates toward net-zero goals, we must simultaneously ensure that our living spaces do not compromise our wellbeing. Findings from this project not only advance our scientific understanding but also provide clear pathways for intervention.

As Professor Nicholas Pleace states, “If we look back at other public health hazards, it took a long time to establish and implement the argument against tobacco fully. We are beginning to observe a similar shift with alcohol, echoing the changes seen with the decline in smoking in society. I believe this field of research will also become one of those areas where increasing evidence about indoor air quality leads to a stronger policy response as awareness of risks to public health increases... INGENIOUS is a remarkable piece of work.

Click here to watch the webinar recording.

Interested in the science and want to read the paper, click here.