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Invisible threat with visible consequences

19 January 2023

There is growing awareness of poor indoor air quality and how this can effect the health and wellbeing of workers. David Flower takes a look at this important issue.

POOR AIR quality is the largest environmental risk to health in the UK according to the Government.

Their statistics1 show that between 2017 and 2025 the total cost to the NHS and social care of air pollutants will be £1.6 billion, with between 28000 and 36000 deaths a year.

Furthermore, over 12 million people living with pre-existing health conditions can find those exacerbated by air pollution.

For years, the danger of outdoor air pollution has been widely known, researched, and discussed. It is only in recent times, particularly with COVID-19 that Indoor Air Quality (IAQ) has come to the fore as a major health concern.

From reduced cognitive function, lung cancer and asthma to COPD and increased risks of heart attack and stroke; the pandemic has shone a light on the public health consequences of poor building ventilation, indoor air contaminants and the threat they pose.

Whilst IAQ research and legislation lags behind that of outdoor air pollution, it continues because of growing awareness, to gather pace. 

Leading bodies such as UK Research and Innovation and the IOM are at the forefront of work around health impact assessments, epidemiological studies, and intervention approaches. The IOM’s most recent contributions in the field have included independent research on behalf of DEFRA and its Air Quality Expert Group.

With 80% of time spent on average indoors, a large proportion in the workplace and with huge numbers of people visiting doctors daily (up to 3 million2 working days lost as a result), businesses need to ask themselves are they doing enough to combat the challenge of poor IAQ and protect their employees?

What are the causes of poor indoor air quality?

Indoor air pollution arises from a multitude of workplace sources, processes, and activities. These range from cleaning activities and materials, furnishings, building composites, moulds, ground gases, paint, heating and even air fresheners. In addition, it also comprises pollutants from outdoor sources.

When trapped in poorly ventilated buildings; those designed with energy efficient airtight construction; or small spaces with increased temperatures, lack of airflow, distribution, and humidity pollutants can reach uncomfortably elevated levels, remaining in the air for prolonged periods.

These include but not restricted to Nitrogen Dioxide, Carbon Monoxide, Volatile Organic Compounds (VOCs), allergens, radon, and particulate matter.

Indoor air pollution can vary dependent on the specific area within a building, and according to some statistics, indoor air pollutants can be two to ten times higher than outdoor pollution.

IAQ is one of the causes therefore of what has been referred to as Sick Building Syndrome. This occurs when conditions within a particular building and its services lead to workers experiencing health symptoms ranging from lethargy, headaches, coughing, wheezing, itchy skin, and congestion. 

In certain sectors such as manufacturing, one of the largest employers in the UK with approx. 3 million workers, the consequences can be far more serious in terms of severe health impacts. The nature of duties in this industry such as welding and abrading, can see prolonged exposure over long shifts and often with inadequate protection and control.

Along with the health consequences the impact of IAQ and SBS on productivity, employee satisfaction and wellbeing, and overall economic growth can be huge. 

Current legislation and guidance

Historically, guidance and legislation around IAQ has been somewhat of a grey, often confusing area, miles behind that of outdoor air pollution and with little enforceable power or clarity. 

This has been due to the complexities involved with indoor air pollution in terms of how you define IAQ: constantly changing internal environments, the evolution of a building/workplace, sources of pollutants and people’s individual perceptions of comfort.

In the UK, the first comprehensive attention given to it with regards to potential health effects was in 1991 with the House of Commons Select Committee Enquiry on Indoor Air Pollution.

The most recent indoor air quality guidelines for England were published in 2019: these sit alongside the WHO European guidelines3. Together with HSE EH404 workplace exposure limits, and COSHH regulations, these set out UK IAQ workplace legislation and guidance around exposure levels, as well as the monitoring and measurement of known pollutants.

The Building Safety Act 20225 has raised awareness around the provision of health and safety of persons in or around buildings and the condition of buildings. 

With the use of CO2 monitors in buildings to measure indoor air parameters, allowing occupants to take control and increase ventilation which leads to an improvement of indoor air quality.

IAQ in the workplace

With greater awareness and now focus given to the issue of IAQ; it is vital that businesses educate themselves and ensure they are doing everything necessary to protect staff as well as visitors.

It can appear overwhelming to know where and how to start evaluating IAQ, comply with legislation, and achieve ISO7730; but having up to date and accurate data is the first step to an effective strategy. 

A comprehensive COSHH risk assessment carried out by an independent Occupational Hygiene consultant will help to analyse those pollutant concentrations which are of concern. This will include location, staff roles, duration, and variability of work. For example, a full day or short term events.

Employers can also employ a workplace survey to ascertain staff opinions and susceptibility as it relates to poor air quality, working conditions and their health and wellbeing. These proactive approaches and demonstrable efforts help to alleviate employee concerns and in so doing assist businesses in retaining and attracting staff. 

From these steps, continual monitoring can be implemented to get a holistic picture, with a state-of-the-art air quality sensor such as those employed by the IOM. 

This cost-effective technology provides continuous monitoring and real-time scientific data 24/7 to offer insight and accuracy around short and long-term exposure levels in often complex indoor environments. 

As Dr Mark Cherrie, senior scientist at IOM explains, “Our research at the IOM has demonstrated that the majority of exposure to air pollution occurs within indoor environments, especially at home and work. We have demonstrated the feasibility of using real-time low-cost sensors to moderate these risks to health."

Sensors are available to measure key airborne indoor air pollutants: 

  • Humidity
  • CO2
  • Carbon Monoxide
  • VOCs
  • Barometric Pressure
  • Temperature
  • Particulates

Range of gases including formaldehyde, carbon monoxide, nitrogen dioxide, sulphur dioxide, ozone, ammonia, and hydrogen sulphide

These measurements presented on a remote dashboard, alongside survey and assessment results enable businesses along with their expert independent occupational hygienist to get a clear and reliable picture of their workplace indoor air quality. 

David Flower, Senior Occupational Hygienist with IOM explains, “A lot of traditional monitoring has been spot sampling, looking at the here and now. The problem with this is it is short-term and does not give a business the full picture.” 

“With the sensor, we are looking at long-term monitoring of indoor air quality to give us and the client a full gage of the situation. This ensures that changing variables within the working environment can be picked up and allows us to then offer the most comprehensive response.”

Armed with this information businesses can take appropriate advice and action to optimise, evaluate and manage current control measures, precautions, ventilation and building design. In so doing they ensure staff and visitor health, comfort, and productivity.

Recommended control measures for IAQ

Once the collation and analysing of data is complete, it should be straightforward to identify priority areas for action and whether a business requires new control measures or improvements/upgrading to current ones.

When it comes to IAQ, control measures divide into passive and active methods dependent on requirements but with emphasis being to eliminate or isolate individual sources.

Passive methods:

  • Improving natural ventilation by opening windows and doors.
  • Limiting the number of occupants in a room.
  • Reassessing room layout and furniture configuration.

Active methods:

  • Introduction of Local Exhaust Ventilation systems.
  • Mechanical ventilation systems that incorporate HVAC systems to provide filtered air.
  • Regularly assessing, cleaning, and maintaining your current filtration and HVAC systems to ensure they are fit for purpose.
  • Humidity control and moisture management through dedicated dehumidification equipment.


IAQ effects businesses and those who operate within them hugely. From performance and productivity, to health, wellbeing, and compliance; the consequences of putting it to the bottom of health and safety strategies can be huge.

Professional organisations such as the IOM make it easy to stay on top of the issue: with remote monitoring, ventilation, and occupational hygiene services to support building owners, occupiers and health and safety managers.

Moving forward, it is likely that IAQ will become an even bigger issue from a legislative and health point of view. Businesses will make real gains now by ensuring they embrace their responsibilities and give it the recognition it deserves.

1 https://tinyurl.com/47ffsen4
2 https://tinyurl.com/ycya8549
3 https://www.euro.who.int/__data/assets/pdf_file/0005/74732/E71922.pdf
4 https://www.hse.gov.uk/pubns/books/eh40.htm
5 https://www.legislation.gov.uk/ukpga/2022/30/enacted

David Flower is senior occupational hygienist at IOM World. For more information, visit http://www.iom-world.org