Combating poor indoor air quality

The topic of air pollution has been highly publicised over the years, with people recognising the impact that it can have on their health. However, as homes have become more efficient thanks to better insulation, the subject of indoor air quality (IAQ) has become increasingly significant.

According to a recent study by Evelina London Children’s Hospital and King’s College London, air quality at 86% of planned new school sites in England exceeded World Health Organization (WHO) targets on major pollutants.

“This indicates that a large number of educational institutions, and likely other types of buildings, are failing to provide safe air for their occupants,” says David Millward, product manager at Elta Group. “The pandemic has further underscored the importance of IAQ, as people have become more aware of the air they breathe indoors.”

Behind closed doors

Poor IAQ is a growing concern, particularly as people spend a significant amount of time indoors where pollution levels can be higher than outside.

According to the Air Quality Expert Group’s Indoor Air Quality report, in the absence of indoor sources of pollution, IAQ is determined by ingress of outdoor air, balanced with pollutant loss processes such as deposition to surfaces and through ventilation.

Most enclosed spaces, such as homes, offices, schools and public buildings, have a wide range of indoor emissions that come from building materials, furnishings, gas and solid fuel cookers, boilers and stoves, the consumption of solvent-containing products, pet dander, dust mites, pollen, and cleaning and personal care products.

Humans are also a source of emissions, including carbon dioxide, human bio-effluents and biological aerosols such as viruses. Although some factors are beyond individuals’ control, such as the building fabric or ventilation in public spaces or workplaces, certain actions can directly influence the concentrations experienced. Dispersion is far more limited indoors than outdoors, so even modest inside emissions can result in higher concentration levels. For example, indoor mould and damp can lead to elevated concentrations of biological aerosols when compared to those typically found outdoors. What emerged from the report is that there is a greater concentration of a diverse range of chemicals found in indoor air compared with outdoor air in the UK.

Standards for acceptable ventilation rates are included in Building Regulations (Part F) and products with a high volatile organic compound (VOC), such as paints, have been regulated through EU Directives. However, these aren’t always well integrated or used to their best effect, according to the report. Additionally, despite a number of labelling schemes for construction products across Europe, currently there aren’t any in the UK.

“Even the ‘perfect’ building with no indoor emissions can still be affected by the ingress of outdoor pollutants, including transport emissions, dust and pollen,” says Stijn Renneboog, deputy secretary general at Eurovent. “That means all buildings are at risk. It also means that no two buildings are alike.

“To aggravate things further, buildings are becoming more energy efficient as we prepare for net zero. Fully insulating buildings presents a double-edged sword. Energy efficiency is greatly improved and issues which lead to poor IAQ, such as draughts and condensation, are reduced. However, pollutants are trapped inside and can gather in higher concentrations. The more airtight buildings become, the higher the risk of poor IAQ, especially if the indoor environment is not adequately managed by correctly designed and installed heating, ventilation and air conditioning (HVAC) systems.”

Negative impact

Poor air quality in homes, schools and other public buildings can have a profound impact, particularly on vulnerable people, such as children and the elderly. Prolonged exposure to pollutants such as carbon monoxide, ozone, nitrogen dioxide and sulphur dioxide can lead to serious health issues, including respiratory issues such as asthma, underdeveloped lungs, increased susceptibility to pneumonia and even cancer. Poor IAQ can also contribute to cardiovascular, developmental and neurological issues. High humidity and insufficient ventilation can exacerbate these issues, creating an environment where pollutants and contaminants thrive.

“In schools, poor IAQ can affect students’ cognitive functions and academic performance, leading to absenteeism and long-term health issues,” points out Millward. “In homes and public buildings, poor air quality can contribute to chronic health conditions, reduced productivity and overall diminished quality of life.”

Poor IAQ can also have an impact on mental health, with potential consequences including stress, anxiety, low mood, insomnia and depression. In fact, figures from the IAQ Matters campaign show that good IAQ helps schools reach their primary goal of educating children by increasing learning performance by 12%. It’s much the same for businesses. Poor air quality due to increased pollution/decreased ventilation is estimated to result in businesses experiencing a 5% drop in work performance. A 5% boost in work performance means:

• 25 minutes longer in the working day
• reduced number of breaks
• 10 less days of sick leave per year.

“The cost of providing good IAQ in office buildings is less than 1% of the labour cost,” says Renneboog. “It makes financial sense to invest in good IAQ.”

Aside from the worrying health issues, poor IAQ can also damage buildings. Condensation promotes mould growth on walls and window frames, which can lead to long-term structural and maintenance challenges.

Our increasingly warm climate can also have a profound impact on IAQ and public health. Elevated temperatures and high humidity can disrupt the body’s natural cooling process, causing discomfort when sweat fails to evaporate effectively.

“High humidity can exacerbate these conditions by creating a stuffy indoor environment and promoting condensation, which fosters the growth of harmful bacteria and mould,” points out Richard Soper of Unico. “Prolonged overheating in buildings can also affect equipment and infrastructure, leading to increased maintenance costs and reduced productivity.”

What’s more, high temperatures can increase the concentration of indoor pollutants by accelerating the emission of VOCs from building materials and furnishings. They can also exacerbate the infiltration of outdoor pollutants such as ozone into indoor spaces.

“The combination of heat and poor IAQ presents a growing public health challenge, that requires coordinated efforts to adapt buildings and urban environments to a warming world,” says Renneboog.

Quality counts

Updates to the Future Homes Standard includes revisions to Approved Document F, which outlines air quality targets and mandates specific ventilation rates to ensure good IAQ. For example, an occupiable room such as an office must receive at least one litre of outdoor air per second per square metre, or 10 litres per second per person.

“These targets are designed to maintain air quality within safe limits as defined by health organisations such as the WHO,” explains Millward. “Additionally, the UK government’s Building Bulletin BB 101 [Ventilation, thermal comfort and indoor air quality] provides separate guidance on ventilation in schools, specifying performance levels to meet UK regulations.”

In England there are extra regulations relating to the air pollutant of most harm to health – fine particulate matter (PM2.5). The Environmental Targets (Fine Particulate Matter) (England) Regulations 2023 set two PM2.5 targets to be met by 2040, requiring that:

• the annual mean concentration is 10 µg m-3 or lower
• the population exposure is reduced by 35% compared to 2018 levels.

The most harmful contaminants in dwellings are PM2.5, PM10, nitrogen dioxide, formaldehyde, radon and ozone 14. The UK has set air quality targets (via the previous government) primarily through its Environmental Improvement Plan 2023, which aligns with WHO guidelines and focuses on reducing some of the most harmful pollutants.

The UK also has legal emission targets for reducing five damaging pollutants by 2030 (relative to 2005 levels), which are to:

• reduce emissions of nitrogen oxides by 73%
• reduce emissions of sulphur dioxide by 88%
• reduce emission of PM2.5 by 46%
• reduce emissions of ammonia by 16%
• reduce emissions of non-methane volatile organic compounds by 39%.

“Public health advocates and parliamentary committees have highlighted the need for more ambitious and immediate action, especially in urban and disadvantaged areas disproportionately affected by air pollution,” says Ian Butler, partnership manager at Eurovent Certification.

There is currently a campaign to incorporate IAQ into Energy Performance Certificates (EPCs) and reform of the system offers an opportunity to introduce the reporting of IAQ metrics.

“In the EU, the new Energy Performance of Buildings (EPBD) directive published in May 2024 is already bringing this into force,” adds Butler. “The EPBD indicates that temperature, humidity, ventilation rates and the presence of pollutants should be taken into account with the energy performance of buildings. Member states have two years to justify the application of the directive, and the means implemented to transpose it into their national text. While the UK is under no obligation to follow the EU’s lead, it is both possible and desirable to incorporate IAQ indicators within EPC certificates.”

Tackling the problem of poor IAQ requires a mixed approach that addresses the key issues, and should cover ventilation, air filtration, temperature regulation, humidity control and air disinfection (see left).

Millward concludes: “By implementing these strategies, building engineers and facility managers can significantly improve IAQ, protecting the health and wellbeing of occupants in homes, schools and other public buildings.”

REDUCING RISKS FROM POOR IAQ

Improving IAQ involves a multi-faceted approach:

• Proper ventilation Installing and maintaining effective ventilation systems is crucial. Mechanical Ventilation with Heat Recovery (MVHR) systems can optimise airflow based on occupancy, ensuring that new air is supplied efficiently while conserving energy.
• Monitoring and assessment Installing monitoring equipment, such as room sensors, can help track levels of pollutants such as temperature, humidity and carbon dioxide. This data can guide adjustments to ventilation systems to maintain optimal air quality.
• Expert consultation Consulting with ventilation experts can help you design bespoke air quality management plans for specific buildings. Experts can give recommendations on best practice for installation and maintenance.
• Compliance with regulations Adhering to building regulations, such as Approved Document F and BB 101, ensures that systems meet required standards and provide adequate air quality.
• Regular maintenance Checking ventilation systems is essential to keep them operating effectively. This includes changing filters, cleaning components and ensuring that all parts are functioning correctly.