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The air you breathe at work

90% of our time is spent indoors, including the time we spend at work. Breathing quality air in our offices or businesses is therefore essential, not only because it will prevent health problems, but also as it relieves stress and increases productivity.

We breathe better, we work better

Harvard Business School1 has shown that there is a direct relationship between ventilation quality and workers' cognitive functions (an indicator of productivity). Its research, part of Harvard's Healthy Buildings programme, involved modifying the environmental conditions in a work environment in order to see how this influenced people's performance and behaviour.

Special attention was paid to the level of carbon dioxide and volatile organic compounds (VOCs), checking their effect on workers. Decision-making, strategy-building and planning by employees all improved when air quality was good.  According to data published by the World Green Building Council2, offices that combine low levels of CO2 and VOCs with good ventilation see cognitive functions among staff increase by up to 101%.

Good ventilation and air filtration are beneficial for health and the quality of life, leading to financial improvements for the company. Research from Harvard University and Syracuse University3 has concluded that improving ventilation in work buildings for less than $40 per person per year would increase production by 8%, representing an increase in productivity of $6500 per employee per year

Sick Building Syndrome

Although our workspaces should be healthy places, office buildings present problems that can lead to what WHO has defined as Sick Building Syndrome (SBS). This name is given to the "set of disturbances caused by poor ventilation, thermal imbalance, electromagnetic charges and suspended chemical particles and vapours that circulate inside the building in which we live or work".4

There are two types of sick building, according to the WHO: temporarily sick and permanently sick. Temporarily sick cases generally involve new or recently refurbished buildings in which the symptoms disappear over time. The symptoms in permanently sick buildings, in contrast, remain for many years.5

The most common symptoms are not serious, but they can be a nuisance in our daily lives and impair our ability to work. Depending on the building, such symptoms may include feelings of tiredness, headaches, dry eyes or throat, nausea and dizziness, all of which improve when leaving the building.6

The Spanish Ministry of Labour and Social Affairs, together with the National Institute of Safety and Hygiene at Work,7 point to insufficient ventilation as being one of the main causes of this problem. Environmental pollutants from various sources will accumulate and affect workers' health if the indoor air is not adequately renewed.

Some of these pollutants come from building and decoration materials, such as formaldehyde, organic vapours, powders and adornments; while others come from office products, such as ozone from photocopiers, or cleaning products; and some particles are introduced in the building from the outside air, such as sulphur dioxide or radon.

The thermal environment can also affect SBS. The National Institute of Health and Safety at Work recommends a temperature of between 23 ºC and 26 ºC in summer and between 20 ºC and 24 ºC in winter, with these values being similar to those recommended in the Building Thermal Installations Regulation (RITE). This regulation also states that relative humidity should be kept between 40 and 60% in order to avoid the appearance of harmful micro-organisms.8

Tips to keep the air in your business or office clean9

  1. Do not block vents with furniture.
  2. Make sure filters are cleaned and changed frequently.
  3. Avoid using products such as adhesives, solvents or strong cleaners. If they are to be used, be sure to monitor ventilation more exhaustively.
  4. Increase the amount of air introduced and extracted by increasing ventilation operating time.10
  5. Increase the proportion of outside air as much as possible.
  6. Take care of maintaining the filters, ensuring they do not become saturated and can therefore work properly.
  7. Keep relative humidity between 40 and 60%.


There is extensive legislation on air quality in work environments, in addition to the Technical Prevention Notes published by the National Health and Safety at Work Institute, which, although not binding, serve as a guide for complying with regulations.

As far as national legislation is concerned, the following Royal Decrees relate to indoor air quality:

1. Royal Decree 1027/2007, of 20th July, approving the Thermal Installations in Buildings Regulation (RITE). This regulation was updated in 2013.

2. Royal Decree 1054/2002, of 11th October, regulating the evaluation process for registering, authorising and marketing biocides.

3. Royal Decree 255/2003, of 28th February, approving the Regulation on classifying, packaging and labelling dangerous preparations.

4. Royal Decree 865/2003, of 4th July, establishing the hygiene criteria for preventing and controlling Legionnaires' disease.

5. Royal Decree 1406/1989, of 10th November, imposing restrictions on the marketing and use of certain dangerous substances and preparations.

6. Royal Decree 396/2006, of 31st March, establishing the minimum health and safety requirements for work with risk of exposure to asbestos.

7. Act 28/2005, of 26th December, on health measures to combat smoking, regulating the sale, supply, consumption and advertising of tobacco products.

The Thermal Installations in Buildings Regulation (RITE)11 sets out the energy efficiency and safety requirements to be met by thermal facilities installed in buildings. It establishes the parameters for acceptable indoor air quality, such as the outside airflow required to renew stale air, as well as proposing different indoor air quality (IDA) categories based on use of the facilities:

  • IDA 1: Optimal quality air in spaces such as hospitals, clinics, laboratories and nurseries.
  • IDA 2: Good quality air in offices, communal areas in hotels and residences, museums and schools.
  • IDA 3: Medium quality air in commercial buildings, cinemas, theatres, function rooms, hotel rooms, restaurants, cafés, nightclubs and gyms.
  • IDA 4: Low quality air not considered for any application. 

A minimum flow of ventilating outdoor air is required in order to achieve the air quality specified by the Regulation, to be calculated using the indirect outdoor airflow per person method, the direct perceived air quality method, the direct CO2 concentration method, the direct airflow per surface area unit method, or the dilution method.

As mentioned above, the National Health and Safety at Work Institute (INSST) has published Technical Prevention Notes (NTP) as guides to good practice.

NTP 243: Enclosed environments: air quality12this is the first note, dealing generally with indoor air to create awareness around an issue that not only affects workers but the whole population.

NTP 289: Sick building syndromerisk factors13, NTP 290: Sick building syndrome: questionnaire for detection14, NTP 380: Sick building syndrome: simplified questionnaire15: discuss sick building syndrome in detail, indicating its causes, effects, and how to detect it.

NTP 315: Air quality: gases present at low concentrations in enclosed environments16: reviews the pollutant compounds found in indoor air in non-industrial buildings (sulphur, carbon and nitrogen oxides, ozone, etc.).

NTP 343: New criteria for future indoor ventilation standards17: proposes establishing new ventilation criteria as a way to improve indoor air quality.

NTP 358: Odours: a quality and comfort factor in indoor environments18: considers the different effects of odours in enclosed spaces, as well as their characteristics or assessment.

NTP 431: Characterisation of indoor air quality19indicates how to conduct basic research into air quality in a building.

NTP 466: Air quality: environmental determination of formaldehyde and measurement of its content in uncoated boards20focuses on one of the most common contaminants, formaldehyde, describing its characteristics, properties and detection methods.

NTP 521: Indoor air quality: emissions from materials used in constructing, decorating and maintaining buildings21reviews the materials most commonly used in buildings, in order to assess their effects.

NTP 549: Carbon dioxide in assessing indoor air quality22deals mainly with how carbon dioxide can be used to collect relevant information on the air quality of a building.

NTP 607: Indoor air quality guides: biological contaminants23sets out the criteria for evaluating indoor air quality.

NTP 741: General dilution ventilation24outlines the design principles of a general dilution system in order to meet prevention targets.

NTP 742: General ventilation in buildings25reviews the requirements of Standard UNE-EN 13779, of September 2005, "Ventilation of non-residential buildings", in order to achieve acceptable indoor environments.

NTP 972: Indoor air quality: volatile organic compounds, odours and comfort26reviews other NTPs dedicated to indoor air quality and addresses the different types of pollutants and their sources, as well as methodologies for determining odours and comfort, and fundamental aspects in assessing indoor air quality.

NTP 989: Indoor air quality: activated carbon filters for improved quality27sets out aspects to be taken into account when using this type of filter, showing how to evaluate its performance.

NTP 1064: Indoor air quality. Biological contaminants (I): sampling strategy28; and NTP 1065: Biological contaminants (II): sampling types29focus on the sampling of biological contaminants when investigating indoor air quality problems. 

NTP 1085: Indoor air quality: office equipment and materials: biological contaminants30describes the potential risks associated with the use of office materials and equipment.

Standard UNE-EN 16798-3:2018 is also recommended for non-residential buildings, dealing with ventilation and air conditioning systems31. The latest standards can be checked here.

The Technical Building Code, which applies to residential buildings, waste storage rooms, utility rooms, car parks and garages, includes a section (section 3) on indoor air quality, establishing the ventilation conditions to be met in such spaces.32










[10] Documento de REHVA sobre cómo operar y utilizar las instalaciones térmicas en la edificación para prevenir la propagación del coronavirus (COVID-19) (SARS-CoV-2) en los lugares de trabajo.























Air quality leaflet

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