Calidad de aire interior en edificios IAQ

Diagnóstico IAQ | Ingeniería HVAC| Validaciones

What is Indoor Air Quality?

Indoor Air Quality (IAQ) in buildings, be they offices, industries, clinics, schools, transportation stations or residential use, can directly affect people’s health and, therefore, their comfort and productivity. It is aimed at the well-being of people, companies and sustainability.

Indoor air quality in buildings varies depending on the concentrations of certain components that can be physical, chemical or biological. They depend on the activity that takes place inside and on its location. At the same time, the architectural typology of the building and its facilities, as well as the maintenance carried out, are important.

Types of air pollutant components in buildings:

  • Physical: dust, noise, humidity and temperature.
  • Chemicals: carbon monoxide (CO), carbon dioxide (CO2), volatile organic compounds (VOC), combustion fumes, etc.
  • Biological: viruses, bacteria and fungi.

How does indoor air quality affect us?

According to studies conducted by the World Health Organization (WHO), we spend 80% of our time indoors.

According to the Environmental Protection Agency (EPA), the interior environment of buildings can be 2 to 5 times more polluted than the exterior.

Poor quality of the indoor environment can lead to health problems such as infections, respiratory problems, allergies and others.

What is the solution to improve indoor air quality in buildings?

Mainly through forced ventilation systems that must include filtration stages, these will vary according to the outside air in the environment and the needs of each building.

In addition, if air purification equipment (UV lamps, photocatalysis sections, electrostatic filters and/or bipolar ionization) are simultaneously incorporated, indoor air quality levels can be considerably optimized.

The design of these systems must always be based on current regulations regarding ventilation and air filtration, and the study of harmful particles that may exist in the environment.

According to reports from the World Health Organization (WHO), PM10 (diameter 10mm), PM2.5 (diameter 2.5mm) and PM1 (diameter 1mm) are the most harmful to health because they penetrate the respiratory system and can lodge in the lungs.

At the national level, there is legislation that establishes limit values ​​for these types of particles. The Regulation of Thermal Installations in Buildings (RITE) classifies the quality of outdoor air (ODA) according to the concentration of gases and particles, and of the indoor air in buildings (IDA) according to the activity that takes place in them. Based on this classification, minimum air renewal values ​​are required by supplying air from outside and marks the minimum types of filtration necessary.

IT Outdoor air classification

  • ODA 1: pure air that gets only temporarily dirty (e.g. pollen)
  • ODA 2: air with high concentrations of particles and/or polluting gases
  • ODA 3: air with very high concentrations of polluting gases (ODA 3G) and/or particles (ODA 3P)

IT Indoor air quality categories based on building use

  • IDA 1 (optimum quality air): hospitals, clinics, laboratories and nurseries.
  • IDA 2 (good quality air): offices, residences (common spaces of hotels and similars, residences for the elderly and students), reading rooms, museums, courtrooms, teaching and similar classrooms and swimming pools.
  • IDA 3 (medium quality air): commercial buildings, cinemas, theatres, assembly halls, hotel rooms and similars, restaurants, bars, party rooms, gyms, sports venues (except swimming pools) and computer rooms.
  • IDA 4 (low-quality air)

IT Minimum outside air filtration according to EN 779 standard

ODA 1 F9 F8 F7 M5
ODA 2 F7+F9 F6+F8 M5+F7 M5+F6
ODA 3 F6+GF(*)+F9 F6+GF+F9 M5+F7 M5+F6

Since the last year 2018, the ISO 16890 standard came into force to replace the European Standard EN 779 and ASHRAE 52.2.

This standard defines new groups of filters according to the size of the particles.

  • ISO Coarse powder (sand, hair)
  • ISO PM10: particle size ≤ 10 μm (pollen, dust)
  • ISO PM2.5: particle size ≤ 2.5 μm (fungi, bacteria)
  • ISO PM1: particle size ≤ 1 μm (flue gas particles, viruses)

Comparative table between EN 779 and ISO 16890:

EN 779 EN ISO 16890
Coarse Powder PM10 PM2,5 PM1
G4 >60%
M5 >50%
M6 >70% >50%
F7 >80% >65% >50%
F8 >90% >80% >70%
F9 >95% >90% >80%

Other differences that this new ISO 16890 standard presents in front of the previous ones are the tests that are carried out on the filters, these are more demanding and subject them to tests in real working conditions, thus increasing the performance of the filtering systems and therefore consequent air quality.

For more restrictive environments where a higher level of filtration is necessary, such as research laboratories, operating rooms or the pharmaceutical industry, the EN 1822 and ISO 29463 standards establish the evaluation methods for high-efficiency filters, classifying them into the following groups:

  • EPA Filters (Efficient Particulate Air filter) – E10, E11, E12
  • HEPA Filters (High Efficient Particulate Air filter) – H13, H14
  • ULPA Filters (Ultra Low Penetration Air Filter) – U15, U16, U17
Filter classes Integral value Local value
Efficiency Penetration Efficiency Penetration
E10 ≥ 85% ≤ 15%
E11 ≥ 95% ≤ 5 %
E12 ≥ 99.5% ≤ 0.5%
H13 ≥ 99.95% ≤ 0.05% ≥ 99.75% ≤ 0.25%
H14 ≥ 99.995% ≤ 0.005% ≥ 99.975% ≤ 0.025%
U15 ≥ 99.9995% ≤ 0.0005% ≥99.9975% ≤ 0.0025%
U16 ≥ 99.99995% ≤ 0.00005% ≥ 99.99975% ≤ 0.00025%
U17 ≥ 99.999995% ≤ 0.000005% ≥ 99.9999% ≤ 0.0001%

Costs and benefits of good indoor air quality

Usually, the adaptation of this type of facilities increases installation and maintenance costs, but the benefits provided by the implementation of improvements to increase air quality should be prioritized.


Facility improvement costs Lower healthcare costs
Maintenance costs Reduces the risk of disease transmission
Air diagnosis costs Decreases concentrations of viruses and bacteria
Lower risk of allergies
Increased comfort
Sustainability image
Less work absenteeism
According to CSR
Productivity improvement
Odour reduction


Indoor air is important for people’s lives, it must be clean and healthy in any environment, whether personal or work, so it can be said that the use of efficient ventilation and air conditioning systems with adequate filtration stages, it is essential to maintain good indoor air quality and thus improve people’s health and quality of life.