Laura King considers how to improve indoor air quality in the office environment.

Who would have thought that indoor air pollution could be worse than some of the world’s most polluted cities? However, that is exactly what researchers at the University of Colorado found when cooking a typical American Thanksgiving dinner. For an hour while cooking, levels of PM2.5 — particulate matter that contributes to the risk of cardiovascular and respiratory diseases — reached 200 micrograms per cubic meter (μg/m3) which is worse than many major cities. As a comparison, the World Health Organization sets a guideline limit of an average of 25μg/m3 over 24 hours.

Although not many roast turkeys will get cooked in the average office, according to the US Environmental Protection Agency, air pollution indoors can still be between two to five times greater than outdoors. Closer to home, a 2016 research report by the Royal College of Physicians and Royal College of Paediatrics and Child Health found that air pollution indoors was just as relevant to our health as outdoor exposure, despite its relatively low profile. It estimated that up to 99,000 deaths a year in Europe are attributable to indoor air pollution, although it is feared that this is a gross underestimation.

However, although still a relatively new field, attitudes to indoor air quality (IAQ) are changing: Defra’s 2019 Clean Air Strategy included actions to improve IAQ, and it is also part of the London Environmental Strategy.

What is the impact of IAQ?

Studies to determine the impact of poor indoor air quality often focus on acute symptoms and have, for example, found that there is a link between eye symptoms (such as dry eyes) and proximity to outdoor traffic, humidifiers and crowding in offices. Another study found that moisture and mould in buildings exacerbated the symptoms of people with conditions such as asthma.

However, the long-term effects of office pollution are harder to assess and this is made all the more difficult by our perceptions of air quality, which can be affected by factors such as overcrowding, noise and distance from windows.

Encouragingly for those looking to influence decisions, research on productivity is easier to conduct and indicates that poor air quality does have an impact. A 2016 study by Harvard and Syracuse Universities, for example, found that employees performed 61% better in an office environment with improved ventilation, lower carbon dioxide and lower emissions of chemicals when compared with a typical office.

Common office pollutants

Indoor air pollution is a mixture of outdoor air pollutants that infiltrate in, as well as pollutants from activities and items inside the building. As you would expect, the sources of pollution are different from those outside, eg air fresheners might be a source of particulate matter, and it is likely there will be more microorganisms. Some of the main categories are as follows:

  1. Biological pollutants can build up in damp environments where there is enough moisture to support and concentrate organisms such as fungi, bacteria or viruses. Examples include legionella, mould or dust mites.

  2. Gases and vapours — including:

    • pollutants that infiltrate from outdoors, such as nitrogen oxides

    • a build-up of carbon dioxide in poorly ventilated spaces

    • carbon monoxide from appliances such as water boilers

    • non-methane volatile organic compounds (NMVOCs) and VOCs from a wide variety of products including cleaning supplies, furnishings, building materials and paints

    • ozone from copiers and printers.

  3. Particulate matter comes from activities such as cooking, disturbing dust or dirt when cleaning, as well as secondary particulate matter formed as a result of chemical reactions (for example when VOCs are oxidised).

What does the legislation say?

Under s.6 of the Workplace (Health, Safety and Welfare) Regulations 1992, employers have a duty to ensure that offices are well-ventilated. Whether achieved by mechanical or natural means this requires workplaces to draw clean air into the building and circulate it so that humidity and a build-up of pollutants are removed and the air feels “fresh” without being draughty. If the air from outside the building is not clean — eg if it is contaminated by traffic fumes — then it needs to be filtered.

How to improve air quality in an office

Every building will be unique and have its own characteristics that affect IAQ. For example, the location will influence the quality of air that is drawn in from the outside, and other factors such as building design, impact of renovations, occupation, furnishings, and activities conducted inside the building will all impact on how good air quality is.

There are three main steps to improving air quality:

  1. Remove the sources of pollutants — this could be by timing activities to avoid exposure to occupants, or by creating physical barriers for pollutants. For example, consider the following.

    • Reviewing cleaning operations to assess whether there better options; can cleaning products be used that release fewer VOCs?

    • Are soft furnishings a source of pollution? Degassing of new furniture and fittings can take place over several years, so if undertaking a refurbishment, consider investing in products that are low emitters of VOCs.

    • Make sure that office equipment such as photocopiers are positioned away from desks.

    • Consider using air doors to prevent pollution from outside entering a building through the main entrance.

  2. Good ventilation is key, as increasingly energy efficient, yet air-tight buildings have the potential to allow pollutants to accumulate. To address this, heating, ventilation, and air conditioning (HVAC) systems should be regularly serviced to ensure that they are functioning properly and are also not themselves a source of pollutants. They also need to be fit for purpose, so if there has been a refurbishment, or changes to the building which might impact on the effectiveness of the original HVAC system, it should be assessed to ensure that it is still meets the needs of occupants.

  3. Consider adopting an IAQ management plan — although more commonplace during building design, an IAQ management plan can also be adopted once a building is occupied. This is a plan that ensures that factors that impact on air quality are regularly reviewed, and formalises a procedure for dealing with complaints. Any IAQ Management Plan produced during building design should include recommendations for maintaining air quality in-use. An IAQ Management Plan could be included as part of a general maintenance programme.

What to include in an Indoor Air Quality Management Plan

An IAQ plan could incorporate the following:

  • the purpose and scope of the plan

  • who is responsible for the plan, and what their duties are

  • whether employees have any responsibilities (for example to only to smoke in designated areas) and how this is communicated

  • a protocol for investigating complaints

  • a schedule outlining the frequency of inspections focused on IAQ, occupant surveys and any associated IAQ monitoring

  • the maintenance plan for HVAC systems

  • any policy for renovations or building works

  • the cleaning policy in relation to maintaining good IAQ

  • any associated training

  • when the plan will be reviewed.


Poor IAQ is thought to have long-term health effects on building occupants, and has certainly been linked to poor concentration and reduced performance. Good ventilation is required by law, but for office-like buildings there are no there are no clear-cut guidelines on how “clean” indoor air should be. Building managers should take a proactive approach to managing IAQ by removing potential sources of pollution, adopting a good maintenance programme and considering implementing an IAQ Management Plan.

Last reviewed 8 May 2019