Why indoor air quality is the next public health frontier
Sarah West, centre director at the Stockholm Environment Institute, sets out why indoor air quality must become a national public‑health priority and why the UK’s public buildings urgently need modern ventilation standards
For decades, the environmental gaze of the United Kingdom has been fixed firmly on the horizon. We have successfully implemented Clean Air Zones and Ultra Low Emission Zones in our major urban hubs and strictly regulating the pollutants that exit our tailpipes and chimneys. However, a significant blind spot remains in our national health strategy. While our focus has been on the air quality of our streets, we spend approximately 90 per cent of our lives in indoor environments that remain largely unregulated and overlooked (Defra Indoor Air Quality report).
Poor air quality now stands as the largest environmental risk to public health in the UK. This is particularly critical within the public estate, where the buildings we rely on, from schools and hospitals to public buildings, often act as reservoirs for a variety of harmful substances. This neglect carries a heavy price tag for the taxpayer, manifesting as a significant burden on the NHS and a persistent drain on national productivity.
Furthermore, indoor air quality is a profound issue of equity. Unlike outdoor pollution, which tends to follow broader geographical patterns, indoor air quality varies wildly based on building maintenance, localised pollution sources like busy roads, and the standard of historical retrofitting. This ensures that certain groups, often the most vulnerable, are disproportionately affected by the air they breathe while seeking public services.
The health and wellbeing effects of poor indoor air are both immediate and cumulative. While the dangers of tobacco smoke and asbestos are well-established and heavily regulated, a host of other pollutants present a quieter but equally serious threat. Many of these substances enter our buildings from the outside.
Research from the SAMHE (Schools’ Air Quality Monitoring for Health and Education) project, led by Imperial College London and the Stockholm Environment Institute at the University of York, indicates that for most schools, particulate matter primarily originates from outdoor sources like road transport and industrial combustion. Once inside, these particles are joined by volatile organic compounds emitted from furniture, paints, and cleaning products.
Beyond external pollutants, the simple act of occupancy introduces risk. Insufficient ventilation allows for the accumulation of volatile organic compounds and carbon dioxide. High concentrations of carbon dioxide are directly linked to reduced attention levels, sleepiness, and headaches, which all sabotage workplace productivity and increase absenteeism. Meanwhile, the accumulation of respiratory aerosols increases the transmission risk of airborne diseases. This was made clear during the Covid-19 pandemic, but it applies equally to other infections like measles, where outbreaks can have devastating implications for school attendance and public health.
Decarbonisation and retrofitting
The public sector is currently under immense pressure to decarbonise, yet this drive for energy efficiency has created a technical paradox. Historically, efforts to “seal up” buildings to prevent heat loss through retrofitting were often poorly thought out, leading to stagnant environments where moisture and pollutants became trapped. This focus on simple airtightness created a recipe for damp and mould, which we now recognise as a severe health crisis.
However, the philosophy of retrofitting is undergoing a vital shift. Initiatives in the city of York, including the Retrofit One Stop Shop York (ROSSY) project and the YorEnergy platform demonstrate that modern engineering has moved past the era of simply blocking drafts. The new standard is to seal buildings tight, but with controlled ventilation. This means buildings are made energy-efficient and airtight, but with the critical addition of controlled, purposeful ventilation. For public and commercial buildings, this typically involves Mechanical Ventilation with Heat Recovery systems, which ensure a constant supply of fresh, filtered air while retaining the thermal energy required to meet Net Zero goals.
This shift is supported by a strengthening regulatory framework. UK building regulations now dictate that any building work affecting airtightness must ensure that ventilation still meets legal requirements for indoor air quality. While this is the default compliance route, further guidance on retrofitting and assessing ventilation risk has been published that, while primarily aimed at homes, is increasingly influencing how we manage the wider public estate.
Research and policy
Despite increased research over the last five years through programs like INGENIOUS and the development of the Air Hub, significant knowledge gaps remain. We still understand far less about the accumulation and interaction of indoor pollutants than we do about outdoor, or how outdoor and indoor pollutants interact. To rectify this, the UK must commit to meeting the 2021 WHO Air Quality Guidelines, which set targets far more ambitious than our current legal safe levels.
Policy remains fragmented, with responsibilities split across departments managing health, building standards, and the environment. We need a unified national strategy that integrates consistent ventilation and air quality standards across all public buildings. This strategy must include robust monitoring, enforcement, and dedicated financing for air cleaning technologies where traditional ventilation is insufficient. We also require stricter emission standards for consumer products and clearer labelling to help estate managers make informed choices about the materials they introduce into their buildings.
Public awareness is the final piece of the puzzle. We must treat building occupants as active participants in air quality management. Tools like the SAMHE monitors and web apps provide real-time data that raise awareness and “nudge” users to act, such as opening windows or adjusting mechanical settings.
Combined with enforced anti-idling zones around public facilities, these behavioural changes can significantly lower the local pollutant load.
The movement to formalise these protections is gaining legislative momentum. The Clean Air (Human Rights) Bill is scheduled for its second reading in March 2026. This bill represents a potential turning point, establishing a legal right to clean air across all four nations of the UK. For those managing the public estate, this legislation would transform indoor air quality from a best practice recommendation into a statutory obligation.
Addressing indoor air quality is far more than a narrow environmental or compliance issue; it is a fundamental public health emergency and a major economic opportunity. Improving air quality is a benefit rather than a chore. Research from the CBI has indicated that meeting WHO standards could boost the UK economy by £1.6 billion annually. When we consider that optimised indoor environments can improve workplace productivity by nearly 10 per cent, the economic argument for immediate action becomes undeniable. By modernising our ventilation standards and committing to a national indoor air strategy, we can turn our public buildings into engines of health and efficiency.
