Historically, cities have been viewed as unnatural environments for humanity, representing a departure from rural life, where clean air and abundant resources are prevalent. Jean-Jacques Rousseau described the isolation experienced in urban settings by characterising towns as ‘the abyss of the human species’. He dismissed cities as ‘pestilential to man’s morals, health, and liberties’. As nations work to move from poverty to prosperity through urban development, the unprecedented scale, speed, and scope of current urbanisation raise concerns about its sustainable trajectory and the potential for cities filled with disease and danger.
Buildings have evolved alongside technological advancements throughout history. Each era has witnessed significant leaps in building technology, shaped by societal expectations and technological possibilities. This evolution demonstrates an increasing reliance on integrated and adaptive systems as crucial elements in building design and operation. From basic mechanical systems to digital and sustainable solutions, technology has become more complex, interconnected, and responsive to human needs. This shift from passive solutions to proactive, intelligent systems aims to create healthier, more comfortable, and sustainable buildings. Disruptive technological advancements change how occupants gauge and perceive their expectations, and influence their interactions with their buildings, fulfilling current technologies’ social promise.
Industrial era’s key advances
The industrial era introduced machinery such as steam engines and early HVAC systems to buildings. Advances in plumbing technology made sanitation systems and indoor toilets possible, dramatically improving public health. Gas lighting initially transformed how spaces were lit, followed by electric lighting in the late 19th century, bringing a more stable and safer lighting source. These developments were not just about functionality, but also about ascending the heights of public health and wellbeing. Mechanisation also extended to elevators in the late 19th century, which enabled high-rise construction. By the 1920s and 1930s, boilers and early air-conditioning systems were incorporated into buildings, especially in urban areas. The increased availability of electricity enabled the installation of more complex electrical wiring. Hence, more HVAC systems facilitated the desired thermal comfort to inhabit buildings and prosper amid humanity’s massive urbanisation. Singapore’s founding leader, Lee Kuan Yew, was convinced that air-conditioning was key to his nation’s achievements, and was the greatest innovation of the 20th century.1
The ‘neglect’ of IAQ
Although the premise of all these technologies was to improve the functionality of a building, public health and wellbeing through the lens of air quality received less attention and emphasis. When building automation systems emerged through digital controls for HVAC, lighting, and security — allowing remote control and more efficient energy management, air quality was not one of the driving forces of smart building technologies. Today, the availability of air quality sensors, IoT devices, and computer-based systems, has enabled ‘smart’ buildings to exist. Additionally, these various system have facilitated monitoring of environmental changes and occupancy pattern variations to allow for responses to any deterioration in indoor air quality.
The narrative of better IAQ in the building still needs to catch up as a priority. To date it has tended only to gain spot momentum during pandemics, wildfires, and volcanic eruptions. Modern buildings are far better positioned to embrace air quality monitoring systems, and act upon their data through their enhanced connectivity than ever before. IAQ data can be capitalised on by integrating HVAC, filtration, and air monitoring systems to propel the cause for better IAQ if incorporated into building designs from day one of crafting building blueprints. This potential for improved indoor air quality through performance integration should inspire optimism about the future of building design and operation.
The significance of indoor air quality
IAQ is a significant factor in physical and mental health, productivity, and quality of life.2,3 Pollutants from building materials, cleaning products, and furniture, can negatively impact indoor environments. Key IAQ issues include volatile organic compounds (VOCs), particulate matter (PM2.5 and PM10), carbon dioxide (CO₂), carbon monoxide (CO), and biological contaminants like mould and dust mites. Poor IAQ is associated with health problems including respiratory and cardiovascular diseases across various settings — including homes, offices, healthcare facilities, and schools.4,5 Fine pollution particles don’t only get into the lungs; they can penetrate lung tissue and enter the bloodstream, leading to inflammation and myriad ailments and serious illnesses, from degenerative to terminal diseases.
Technologies focused on air quality and filtration can improve indoor environments not only from an aesthetic standpoint (see Figure 1), but also from a health and well-being one — an essential metric for ‘smart’ and ‘green’ buildings. The COVID-19 pandemic highlighted the need for cities to enhance their pandemic resilience, increasing interest in innovative technologies for IAQ and occupant health. In response to this awareness, there has been a growing demand for real-time air quality monitoring and advanced filtration systems to suppress virus transmission.
Effective air quality governance — including policy frameworks, monitoring systems, and public engagement — is critical for improving IAQ. To govern air quality, we ought first to measure continuously and reliably. Envisioning innovative solutions in a noisy air quality landscape with conflicting opinions and approaches can be challenging. Issues with filter selection can arise from several factors — including inadequate filter efficiency, excessive face velocities, and inappropriate fit and installation — leading to air leaks, which defeats the intended purpose of installation in the first place. Furthermore, unnecessary filter efficiency upgrades and excess filter surface area do not effectively contribute to filtration. These conditions can lead to a higher filter pressure drop without a substantial gain in filter efficiency, and have a counter-productive effect on energy efficiency. Ironically, this increased energy burden can trigger a higher scope of greenhouse gas emissions, meaning that ineffective filters can become part of the pollution problem, rather than the solution.
Critical factors when choosing an air filter
A critical factor in effectively choosing an air filter is the physical and chemical characterisation of suspended air pollutants present in the outdoor air that contribute to health issues and discomfort.6 Filtration engineers must prioritise the contaminants that adversely affect occupant health and compromise the performance of filtration and HVAC systems to achieve optimal results. It is crucial to proceed with care when setting standards, as overly simplistic guidelines may overlook the complexities of diverse occupancy scenarios and their unique indoor air quality challenges. Understanding how filtration and HVAC systems react to these variations is essential, especially in environments close to healthcare facilities, schools, commercial aircraft, restaurants, and food courts. Implementing filtration, HVAC, and building design standards — including air quality considerations — can contribute significantly to sustainable building practices. Ensuring public health and wellbeing is vital for creating safe and suitable environments for human occupancy.
Effective governance relies on dependable, real-time data that drives policy and practice. Recent advancements in sensor technology enable continuous IAQ monitoring, offering valuable insights into pollutant levels, temperature, humidity, and CO₂ concentrations. Building owners and operators can use this data to make prompt adjustments, such as enhancing ventilation or fine-tuning HVAC settings, to maintain optimal indoor air quality. Governance can help ensure that air quality standards are consistently upheld by mandating IAQ monitoring in public buildings, workplaces, and busy areas. The data collected can also be used to support long-term research, aiding policymakers in understanding indoor pollution patterns, and crafting more targeted regulations. By providing public access to IAQ data, individuals can be empowered to make informed decisions about their health.
Technological innovation and sustainable building design
Advances in HVAC systems, air filtration technologies, and sustainable building materials, are critical for improving indoor air quality. For instance, energy-efficient HVAC systems with pleated hybrid media filters are essential for effectively removing airborne particles and odours. Combining mechanical and chemical filter media enhances particle capture and odour control, improving indoor air quality without excessive energy use. However, space limitations within air-handling units can hinder the incorporation of larger surface area filters, which is counterproductive given the high particle concentration in fresh and pre-filtration stages. Short filter lifespans lead to frequent maintenance, building operations disruptions, and particle dispersion risk from improperly handled filters, particularly in regions needing more adequately trained maintenance personnel.
Moreover, smart systems that automatically adjust ventilation based on pollutant levels offer a proactive approach to maintaining IAQ. However, the need to balance energy efficiency with adequate ventilation is a significant challenge; increasing ventilation can lead to higher energy consumption, and potentially introduce a variety of outdoor pollutants with variating concentrations, complicating air filter performance when filters become prematurely clogged due to particle deposition on depth filter media (see Figure 2). Engineered filter selection targeting the contaminants’ type, size distribution, and concentration relative to the pore size distribution of filter media, can further extend the stationary stage of depth filtration, leading to sustainable filter performance, as illustrated in Figure 3.
Pursuing sustainable and healthy living integrates system technologies that prioritise improved indoor air quality from design to operation. Awareness of IAQ in our building environments should extend beyond those that house newborn children, or elderly family members suffering from chronic respiratory conditions. Striving for better indoor air quality should be a standard expectation, rather than a luxury reserved for the fortunate few. This crucial equity aspect emphasises the need for building systems that foster healthier air quality for all occupants, regardless of socioeconomic status. The challenge of consistently delivering clean, fresh air is significant, yet recognising it as a priority in building design offers great potential. Today, we can enhance human productivity, health, and wellbeing, by addressing these important issues.
The emerging need for systems thinking
Buildings have historically utilised technology that reflects the knowledge available during their time, often responding to environmental challenges and societal demands. As humanity progressed from basic mechanical systems to digital and sustainable solutions, technologies have become more complex, interconnected, and responsive to human needs. This evolution marks a shift from passive solutions to proactive, intelligent systems that aim to create healthier, more comfortable, and more sustainable buildings. However, a systems thinking approach is imperative to capitalise on the availability and potential impact of these technologies, particularly when it comes to HVAC, filtration, and air quality monitoring. Ultimately, embracing such an approach requires systems thinkers and building users who behave responsibly when interacting with their buildings.
Each era represents a significant advancement in building technology, driven by the concurrent evolution of societal expectations and technological capabilities. This trajectory suggests an increasing dependence on integrated and adaptive systems, which are essential components in building design and operation.
Air quality governance is crucial for transforming the potential of improved IAQ into a tangible reality. It is vital in protecting public health, enhancing wellbeing, and fostering sustainable indoor environments. Effective governance can tackle IAQ challenges in residential, healthcare, and commercial settings through regulatory standards, real-time monitoring, technological innovations, and public education. Successful case studies from the United States, Singapore, and the European Union demonstrate the positive outcomes that can arise from proactive IAQ governance.7,8 As urban areas expand and buildings grow more complex, the demand for effective IAQ governance will continue to rise, placing more emphasis on air quality data acquisition. The knowledge provided by such data can help governments enact laws and regulations that foster public human health and wellbeing.
Humanity can achieve sustainable and safe living by prioritising IAQ as a crucial environmental and public health policy component. This should be complemented by significant realignments, one of which is adapting social responsibility toward an environment that saves our planet. As we look to the future, the need to enact change and make critical decisions becomes increasingly crucial in our journey of realignment, especially in the light of the ongoing impacts of climate change. Perhaps William James was right when he said: ‘When you have to make a choice and don’t make it, that is in itself a choice.’ We must acknowledge our shared responsibility to steer our planet toward a more sustainable trajectory where the promise of IAQ in healthy buildings can be realised.
When we genuinely commit ourselves to improving IAQ, we can accomplish healthier air in buildings by creating nurturing, resilient, and sustainable environments for our homes, public spaces, and places of work. Technologies hold immense promise to transform our cities and buildings into pleasant and healthy living environments. There is more to weaving in the tapestry of air quality than installing high-efficiency air filters — such as continuous air quality monitoring accompanied by HVAC systems that can respond to a variation in IAQ and human occupancy. Humanity possesses the tools, led by our voices, to challenge and change the IAQ status quo, and we only require the appropriate conditions to propel and govern the cause of enhanced air quality. Amid growing climate change concerns, we must remember that we have not inherited the Earth from our ancestors, but borrowed it from our children. Therefore, we are responsible for leaving behind a cleaner planet, envisioning a future filled with clean, fresh air worth fighting for.
Dr Iyad Al-Attar
Dr. Al-Attar is a mechanical engineer and an independent air filtration consultant. He is also a visiting academic fellow at the School of Aerospace, Transport, and Manufacturing at Cranfield University, consulting for air quality and filter performance relevant to land-based gas turbines. He is the first associated air filtration consultant and Indoor Air Quality (IAQ) patron for Eurovent Middle East and EUROVENT, respectively, and an editorial member and referee for the Filtration Society (UK) and the Journal of Cleaner Production. His expertise focuses on designing and performing high-efficiency filters for HVAC and land-based gas turbine applications, particularly on the chemical and physical characterisation of airborne particles. Dr Al-Attar is reading for an MSc in sustainable urban development for air quality governance in sustainable cities at the University of Oxford. His current research at the University addresses the importance of air quality inclusion as a rudiment of sustainable urban development. He has authored many articles on air quality, filter design, performance, particle characterisation, and climate change.
References
1 Singapore’s founding father thought air conditioning was the secret to his country’s success. Lee K. Vox online. Vox Media, 23 March 2015. https://tinyurl.com/5n7na9th
2 Wargocki, P. 2016. Ventilation, Indoor Air Quality, Health, and Productivity. Ergonomic workplace design for health, wellness, and productivity. pp.39-72. Taylor & Francis, 2016.
3 Deng Z, Dong B, Guo X, Zhang J. 2024. Impact of Indoor Air Quality and Multi‐domain Factors on Human Productivity and Physiological Responses: A Comprehensive Review. Indoor Air 2024; (1): 5584960. 8 April 2024. Wiley Online Library.
4 Ukpene AO, Molua OC, Ukpene CP, Emagbetere JU, Igbogbor JC. 2023. Health Impact of Indoor Air Quality: Biological, Physical and Economic Considerations. Journal Healthcare Treatment Development December 2023-January 2024. 2023; 41: 27-38.
5 Kumar P, Singh AB, Arora T, Singh S, Singh R. 2023. Critical review on emerging health effects associated with the indoor air quality and its sustainable management. Sci Total Environ 2023; May 10:872:162163.
6 Gherasim A, Lee AG, Bernstein JA. 2024. Impact of climate change on indoor air quality. Immunology and Allergy Clinics 2024; 44(1): 55-73.
7 Pérez-Bou S, Kishnani N, Dutta, A. 2024. Human factors for a successful Integrated Design Process in Zero Energy Buildings: leadership, trust, and goal orientation. A case study in Singapore. Architectural Engineering and Design Management 2024: pp.1-18.
8 Morawska L, Allen J, Bahnfleth W, Bennett B, Bluyssen PM, Boerstra, A et al. 2024. Mandating indoor air quality for public buildings. Science 2024; 383 (6690): 1418-1420.