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With Clean Air Day nearly upon us, Rachel Lekman looks at the importance of indoor air quality

There's a common misconception that our indoor air environment is a reflection of the outdoors and that by tackling the latter we will solve the larger problem of air pollution.

Given that we spend around 85% of our time indoors, and indoor air pollution is estimated to be 3.5 times worse than the air outside, indoor air quality is an important issue in its own right - especially given the spotlight currently being shone on the importance of providing safe work environments.

Whilst a full return to the office may not be imminent, we now have an ideal opportunity to address the air quality issues inside our buildings.

Instead of continuing with business as usual, we can use this gift of time to come back better and create healthier workplaces for employees.

Clean Air Day is a fantastic opportunity to discuss Indoor Air Quality

Rachel Lekman Rachel Lekman Channel marketing manager

What's causing poor indoor air quality?

Modern buildings are designed to be airtight. This is a must if the industry is to lower its carbon footprint but it can lead to some unintentional problems.

A lack of ventilation in an airtight building will mean the indoor environment quickly becomes stale and stuffy. This build-up of excess moisture and CO2 can result in illness and the growth of mould in the building. Air conditioning, or the lack of, similarly allows for an increase in humidity as well as leaving unfiltered particles suspended in the air.

There are also many pollutants which are generated from inside the workplace itself. Cleaning products, solvents, dust, carpet fibres, photocopy residues and building materials, otherwise known as volatile organic compounds (VOCs), create quite an unhealthy cocktail of contaminants which eventually filter throughout the office.

Risks to health and wellbeing

Breathing in the pollution found outside can have disastrous effects on our health, yet often we fail to recognise when we're suffering the effects of indoor air pollution.

"Sick Building Syndrome" is a phenomenon which is increasing amongst office employees, and involves a collection of symptoms related to a certain building. Dry or itchy eyes, throat and skin, headaches, lethargy and irritability are all commonly reported symptoms which increase in severity whilst in the office and improve or disappear when away.

Although Sick Building Syndrome is still poorly understood, physical and environmental factors such as ventilation and cleaning products have all been linked to the experienced symptoms.

As mentioned, a poorly ventilated office means a subsequent increase in CO2 levels. Worryingly, research is suggesting that levels as low as 1,000 parts per million can result in health problems and poor cognitive functioning even if exposed for only a few hours.

There is also research to link indoor air quality (IAQ) to productivity at work. A YouGov survey commissioned by the Building Engineering Services Association (BESA) found that almost 70% of office workers believed poor air quality had a negative impact on their day-to-day productivity. 68% of these experienced lapses in concentration whilst 67% reported suffering from fatigue whilst at work.

Of course, we now have the added risk of COVID-19 which some scientists suspect can be transmitted through the air, creating another air quality issue which must be tackled for the sake of employee health.

How can we improve indoor air quality?

Rachel Lekman Rachel Lekman Channel marketing manager


Effective ventilation should be the starting point when looking to improve IAQ. Whether by natural or mechanical means, ventilation should remove stale and humid air whilst circulating fresh air from outside of the office.

Although opening windows is one way of achieving this, it is also uncontrollable and often leads to thermal discomfort. As reducing COVID-19 transmission is central to making offices fit for return, controlled ventilation which provides a constant supply of fresh air is a must.

Mechanical Ventilation is intended to provide the required steady stream of fresh air, ensuring all employees benefit from the removal of stale air, rather than those lucky enough to be sitting by an open window.

There are, however, recommendations from REVHA on how to operate mechanical ventilation systems to prevent spreading COVID-19. REVHA recommends that systems should not be switched off and should instead operate at a lower speed when the building is not in use. When employees can again return to the office, ventilation should operate at a nominal speed at least 2 hours before the building opens, and switch to a lower speed 2 hours after the building has closed. Central recirculation is not recommended due to the risk of recirculating contaminated air.

Mechanical Ventilation with Heat Recovery (MVHR) systems are able to deliver the required ventilation but do so in an energy efficient way, so that the energy used to heat the indoor air, isn’t just ‘thrown away’ when the fresh air is brought in. They can capture up to 80% of the heat energy from the outgoing air to bring the incoming air nearer to the desired temperature, meaning less energy is required to bring the fresh air to room temperature.

Air Conditioning

Many modern air conditioning systems come fited with powerful filtration which can filter out harmful airborne pollutants and pathogens. Not only will this improve the health of hay fever and asthma sufferers by removing allergens such as dust and pollen, but it will also minimise the risk of Sick Building Syndrome.

The more obvious benefit of air conditioning is the ability to remove humid air by providing a constant, cool temperature which boosts productivity and alertness.

Importantly, the HSE has stated that the risk of spreading coronavirus via air conditioning is extremely low  as long as there is an adequate supply of fresh air and ventilation.

HEPA and Activated Carbon Air Filters

Air filters prevent certain particles and molecules from remaining in the air we breathe. HEPA filters, in particular, are excellent in protecting our health. By capturing dust and allergen particles as well as some VOCs, air purifiers equipped with HEPA filters can improve IAQ drastically.

However, there are many gaseous substances that HEPA filters cannot touch. In these cases, carbon activated air purifiers should be considered. Activated carbon air purifiers work by trapping harmful molecules on a bed of activated charcoal, eliminating them from the air.

These systems are extremely effective in filtering out numerous VOCs including gases given off by cleaning products, drying paint and cigarette smoke. It's important to note that carbon activated filters require replacing once they become saturated with pollutants.

Air Quality Monitoring

How do we know the quality of our indoor air unless we are continuously monitoring it?

To ensure our office HVAC systems are optimised, we need access to accurate information, such as the local temperature and humidity and levels of CO2 and pollutants.

From here we can adjust our buildings accordingly. 

Raising Awareness

It's so important to continue to bang the IAQ drum, raising awareness amongst building owners, employers and employees. HVAC contractors themselves should absolutely get involved in informing communities on the ways health and wellbeing can be improved via IAQ.

Clean Air Day is taking place on 8th October 2020, shining a light on air pollution and the damage it causes every day.

This is a fantastic opportunity to discuss IAQ with businesses, no matter how big or small, and ensuring they're aware of best HVAC practices which will help them create a healthier working environment.

There'll be an informative webinar on the day at 4 pm where Mitsubishi Electric's Mark Grayston will be part of a panel discussing office-based air quality issues. For those looking to raise awareness themselves, the organisers have provided a huge range of free resources.

BESA has long championed the need to monitor and improve the air quality within our buildings, and also have a wealth of useful information and resources freely available.


COVID-19 has forced us to take a better look at our indoor environments, and whether or not they're good for our health.

As we continue to work from home, there is arguably no better time to tackle the problem of poor IAQ inside our offices.

Because pandemic or not, protecting employees from harmful pollutants and airborne viruses whilst at work should be a given, and ensuring new or existing HVAC systems are optimised for long-term health is not only a good place to start, but is also necessary. 

Rachel Lekman is channel marketing manager