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What is sick building syndrome?

Published on 5 May, 2023

Indoor air quality,

Experiencing symptoms of illness or general discomfort when you are in a building, and improvement and relief when you leave? Then it’s clear: you are suffering from Sick Building Syndrome.

What is the sick building syndrome

The term “sick building syndrome” is the name used to describe a medical condition in which users of a building experience symptoms of poor health and comfort as a result of spending too much time indoors.

Sick building syndrome causes

The causes of sick building syndrome are many and include poor indoor air quality, influenced by the presence of pollutants such as volatile organic compounds, carbon monoxide, mould and dust, as well as a lack of adequate ventilation, high temperatures and excessive humidity.

Volatile Organic Compounds (VOCs)

The main sources of these easily evaporating chemical compounds are building materials and furniture, photocopying machines, pesticides, cleaning products, aerosols, office supplies, personal care products and paints and solvents.

It is important to mention that the concentration of VOCs in the air can vary depending on the source, temperature, humidity and ventilation in the environment in question.


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PM particles and biological pollutants

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PM10 and PM2.5 particles are inhalable microscopic fractions that in some cases can cause damage to the body.

Most of the particles found indoors come from particles migrating from outside and avoiding this depends on several factors such as filtration systems, ventilation rates or the main activity of the building users.

Then there are the biological pollutants, which include viruses, bacteria, moulds that use particulate matter as a means of diffusion and transport.

By controlling the PM particles and the relative humidity level in a building, the spread of some sources of biological pollutants can be minimised.

Carbon monoxide

Vehicle exhaust fumes, gas cookers, generators and poorly maintained ventilation and air conditioning equipment are the most common indoor sources of CO. Even at low concentrations, CO can cause fatigue in healthy people and chest pain in people with heart disease.

Carbon dioxide

This colourless, odourless gas can cause numerous health effects. The occupants of buildings themselves are the main source of carbon dioxide due to the CO2 exhaled during the breathing process.

Main symptoms

The best known symptoms of sick building syndrome are:

  • Headaches
  • Dizziness
  • Rhinitis
  • Breathing difficulties
  • Nausea
  • Dryness and skin irritation
  • Mental fatigue
  • Difficulty concentrating
  • Irritation of the eyes, nose and throat.
  • Tightness in the chest
  • Fatigue
  • Fever

This medical condition can affect people differently and the symptoms can be similar to those of other illnesses.

It is therefore important to analyse whether there is an improvement when leaving the building (and worsens when returning indoors) and to rule out other pathologies by medical examination.

Prevent sick building syndrome

Indoor air quality is essential to prevent the factors that cause sick building syndrome and therefore monitoring indoor air quality is crucial to ensure the health and well-being of people in buildings.


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There are CAI sensors on the market with IoT technology that allow real-time monitoring of environmental conditions in buildings. In this way, parameters such as CO, CO2, VOCs, PM2.5, PM10 and the environmental variables of temperature, pressure and humidity that directly influence indoor air quality can be monitored and immediate decisions can be taken to create healthier spaces, such as:

Better maintenance of the air-conditioning system

Maintenance of the ventilation system can improve indoor air quality. Air conditioning systems need regular maintenance, including filter changes. Did you know that filters have a MERV rating, which indicates the size of particles they can trap?

Open windows to improve ventilation rates

Providing the users of a building with natural ventilation and increased fresh air flow has positive effects on the health of workers, increasing their comfort and productivity, something that can easily be known by monitoring air quality and knowing when it is important to promote ventilation.

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