Guide to Indoor Air Quality (IAQ) standards in the UK

Guide to Indoor Air Quality (IAQ) standards in the UK

By Sophie Neaves on Fri 17 May 2024

Guide to Indoor Air Quality (IAQ) legislation in the UK

On average, people in the UK spend up to 90% of their time indoors, where air can become five times more polluted than outside. Indoor air pollution is often unnoticed until it impacts health. As many continue working from home, maintaining good indoor air quality has become increasingly crucial. Unsurprisingly, with this increased risk to public health from poor air quality, there have been amendments to existing legislation in the UK, as well as new rules and regulations to familiarise yourself with. 

What is indoor air quality?

Indoor Air Quality (IAQ) refers to the quality of air within and around building structures, specifically concerning the health and comfort of the people living there. It’s influenced by several factors such as pollutants inside or outside the home including biological contaminants, ventilation rates, temperature and humidity levels. Poor air quality is detrimental to the health of occupants in the short term and long term, causing respiratory issues, headaches and decreased cognitive function. To maintain good indoor air quality the property should be assessed for damp and mould, volatile organic compounds and combustion byproducts and solutions investigated including air filtration, proper ventilation and putting measures in place to reduce or eliminate pollutant sources. 

Understanding indoor air pollution

Although we’re aware that many activities within the home generate airborne pollutants that can be detrimental to our health, we lack comprehensive knowledge about the precise sources of these pollutants, the ways they interact with one another and their ultimate destinations. 


A UKRI-funded project aims to better understand indoor air pollution and its health impacts, focusing on homes in the city of Bradford. While regulations address outdoor air pollution, indoor exposures from sources like cooking, heating, and cleaning are often overlooked. The project will quantify indoor pollutant levels and examine the household behaviours that contribute to exposures, identifying effective interventions. They will also work with authorities to develop policy recommendations for improving indoor air quality in homes across Bradford and the UK. 

What are the standards for indoor air quality?

Whilst there isn’t an overarching legislation currently in place, there are a number of different standards and guidelines that encourage compliance with indoor air quality regulations.

UK building regulations: approved document F

These 2021 amended regulations mandate higher ventilation rates and mechanical ventilation for airtight new homes to improve indoor air quality. It specifies increased whole-building airflow, room-specific background ventilation, and purge ventilation requirements based on window openings to allow sufficient air changes per hour.

WHO Indoor air quality guidelines

These protect public health from a number of chemicals found in indoor air that can have negative health effects in homes if found in large quantities, or for long periods. Three main groups of indoor pollutants are identified including biological indoor pollutants (dampness and mould), chemical pollutants, and those from the combustion of indoor fuels. The guidelines outline how poor air quality can be reduced and the dangers of contaminated indoor air.


NICE Indoor air quality at home guidance

These guidelines cover indoor air quality in residential buildings, they look at how to achieve good air quality in homes and include recommendations for architects and designers to take into account for indoor air quality alongside builders and developers complying with building standards.


Indoor Air Quality Guidelines for VOCs in the UK

These outline recommendations on acceptable levels of volatile organic compounds (VOCs) in indoor air within the UK to protect occupant health and wellbeing.

Awaab’s Law and Social Housing (Regulation) Act

This legislation, currently in consultation in the UK, was driven by the death of 2-year-old Awaab Ishak from exposure to mould in his home. It aims to enforce more stringent and timely action for landlords to ensure safe living conditions and better regulation of social housing. Read in our guide, and how to meet requirements. 


Clean Air (Human Rights) Bill

Known as Ella’s Law, named after Ella Adoo Kissi Debrah, the first person in England to have air pollution named as the cause of death. This is a proposed legislation in the UK that aims to make it a legal human right to breathe clean air and bring air quality in every community to minimum WHO standards.


Building Engineering Services Association (BESA)

The ground breaking standard BS40102 (part 1) offers a framework for evaluating, tracking, and documenting indoor environmental quality (IEQ) across non-residential buildings. It includes evaluation and rating methodologies for various factors impacting IEQ, including air quality, lighting, thermal comfort and acoustics.


The Future Homes and Building Standard

The UK government has pledged to implement new standards, guidelines and regulations that will require all newly constructed homes from 2025 onward to generate 75-80% fewer carbon emissions compared to homes built according to the current regulations.


Indoor air quality testing

Assessment, testing and measurement of indoor air quality are key to maintaining safe levels, and there are various methods used such as:


  • CO2 monitors that measure carbon dioxide levels and airflow rates. CO” levels in the air are quantified in parts per million (ppm). A concentration of 1000ppm which is roughly 10 litres of CO2 exhaled per second by each occupant. If readings persistently surpass 1500ppm it signifies inadequate ventilation, prompting the need for ventilation improvements. 

  • IAQ monitors are integrated sensors that simultaneously measure multiple parameters like temperature, humidity, CO2, VOCs and PM.

  • Barometers measure airflow rates through vents/ducts to ensure adequate ventilation and air exchanges.

  • Tracer gases are inert gases released and measured to determine air mixing, flow paths and ventilation effectiveness. 

  • Air sampling can also be used to analyse for specific pollutants like VOCs, particulates and mould.


How to improve indoor air quality

  • Increase ventilation: proper ventilation is crucial for improving indoor air quality. Consider mechanical ventilation with heat recovery (MVHR) systems during construction or renovation. These solutions provide continuous filtered fresh air while recovering heat to improve energy efficiency. Airflow rates must be measured and calculations submitted to building control to ensure compliance. Installing an effective and economical MVHR system requires consulting ventilation experts such as Airflow Developments experienced technicians. 
  •  Controlling the source of pollutants: Finding and reducing sources of indoor pollutants like combustion appliances, building materials, cleaning products and more. Opt for low-VOC products, properly vent combustion appliances, and control moisture to prevent mould and ensure adequate ventilation in kitchens and bathrooms.
  •  Air purification: this helps remove particulate pollutants, gases and odours. Consider installing whole-home air purification systems for enhanced filtration.
  •  Cleaning and maintenance: Regularly clean or replace filters, vents and ductwork where necessary to prevent recirculation of dust and pollutants. Upgrade older ventilation equipment and look to the most efficient solutions to improve airflow and filtration.  
  •  Check if recirculation is efficient: Ensure any air ventilation systems are not recirculating stale indoor air excessively by checking the outdoor air intake, filter condition, and overall airflow balance through testing and balancing. 

For more information with tips to improve your Indoor Air Quality read our guide.


How Airflow can help

Take a look at our MVHR product range, or get in touch with our experts to help find exactly what you need to improve the indoor air quality in your properties. Our selection software can match you with the products to best suit your needs and ensure guidelines and standards are upheld.