Indoor Air Quality Measurements

Indoor Air Quality (IAQ) in buildings and homes is an essential factor that must be considered when assessing the risk of safety and health of attendees and employees who may be present or reside in these buildings. The risk assessment will provide the measures that the employer/owner must take, to ensure the safety and health of the employees or third parties who may visit these buildings.

IAQ issues occur in buildings where the concentration of chemical or biological agents is such, that can adversely affect people inside the buildings. Some of the common symptoms regarding the health of the employees in cases of inadequate or insufficient IAQ are headache, nausea, fatigue, drowsiness, dizziness, respiratory problems, chest tightness, dry throat, skin rashes, red eyes, stuffy or runny nose and loss of concentration.

These symptoms are commonly known to possibly be related to Sick Building Syndrome and Building Related Illnesses. Namely, they may be associated with a specific set of symptoms and clinical abnormalities found in employees working in the same space.

Possible causes of IAQ related problems:

  • Insufficient supply of outside air for heating, ventilation and air conditioning systems (HVAC).
  • Poor design, insufficient maintenance and cleaning, malfunctioning of air conditioning systems.
  • Pollutants found in the outside air that is entering the building.
  • Emissions from sources inside the building, such as gas emissions from building materials, furniture and other equipment.
  • Accumulation of dust in the air inside the building.

Dust and fibers, temperature, humidity


Internal sources include dust from poor cleanliness, inefficient vacuum cleaners, building materials, fungal seeds, smoke, duct insulation, asbestos, carpet fibers and paper fibers from the use of photocopiers and other related equipment.

External sources include gaseous urban pollutants, construction activity and emissions from motor vehicles, factories, fires, and hazards.

The particle size determines whether the dust can reach the lungs. The potential health risk from certain types of dust is related to toxicity and particle size. Dust particles are measured in micrometers (μm). Dust with a particle size between 0.1-10 μm penetrate the larynx and lungs and may adversely affect health. Dust particles larger than 10 μm are trapped in the nose. On the contrary, inhalation of extremely small particles (<0.1 μm) leads to their expulsion upon exhalation.

Health hazards

Excessive accumulation of dust particles can adversely affect the skin, eyes and respiratory system. Symptoms include eye, nose, throat and skin irritation as well as coughing, sneezing and breathing problems.

Certain types of dust are toxic. Long-term exposure to asbestos fibers increases the risk of lung cancer. Other types of dust, such as those that derive from lead and mercury compounds as well as silica dust, can cause a variety of diseases such as poisoning and silicosis (a form of pneumoconiosis due to the accumulation of silica dust in the lung tissue).

The quantitative recording of the concentration of airborne dust E (PM10) and dust A (PM2.5) is included as a fraction of air mass in micrograms per cubic meter. In addition, a line graph indicator informs you of the state of the particle load.


The presence of the following situations, activities or products in an indoor workplace may result in increased levels of dust in the indoor air:

  • Exposed building materials (e.g. cement, insulation materials).
  • Renovation/ Conversion of the buildings.
  • Air ducts that are loaded with dust.
  • Dust and dirt on the air intake grilles of ventilation systems.
  • Dusty filters.
  • Dust and/or odor deposits on humidity regulators.
  • Use of ultrasonic humidity regulators.
  • Smoke from tobacco products.
  • Handling of dusty materials.
  • Paper shredders.

Exposure control

  • Maintaining an adequate air purification system.
  • Regular cleaning of the air circulation system.
  • Frequent cleaning of dusty areas.
  • Use of local exhaust ventilation in areas where there is excessive dust due to renovations or movement of materials.
  • Creation of negative air pressure and local exhaust ventilation in the designated smoking areas.
  • Prohibition of recirculation of air containing excessive levels of dust.

A human hair has a diameter of about 50 to 70 µm. Comparative to the diameters of inhaled dust fractions (PM10) and particles reaching the cells (PM2.5).

Carbon Dioxide (CO2)

CO2 is exhaled along with aerosols containing SARS-CoV-2 from individuals infected with COVID-19 and may be blamed for indoor SARS-CoV-2 virus concentration. CO2 measurements by indoor air sensors, promise to monitor indoor aerosols and therefore help reduce the risk of transmitting the COVID-19 virus and other respiratory diseases.


The exhalation of the employees in a building is the main source of CO2. Carbon dioxide is exhaled as a by-product by all living organisms. Therefore, it must be removed through the building ventilation system. In case of defective or insufficient air conditioning system, there is an increase in the concentration of CO2 levels and at the same time, a decrease in normal oxygen levels inside the building.

Health hazards

Carbon dioxide is not a toxic gas. However, any increase in the concentration of this gas, reduces the concentration of oxygen indoors. Decreased oxygen causes people symptoms such as dizziness.

Recommended levels of CO2

CO2 concentration in atmospheric air is approximately 330-350ppm (594-630mg/m3). In indoor workplaces, its concentration is higher due to the fact that people exhale CO2 at a rate approaching 0.3 liters/minute (0.3 liters/min) when performing light duty work. It is recommended for indoor air CO2 levels to not exceed by 700 ppm (1260 mg/m3) the concentration of gas in the atmospheric air.


The rate of CO2 extraction from a ventilation system indicates the rate of fresh air supply to an indoor workplace. Typically, CO2 levels in an indoor workplace indicate how well designed and functional a ventilation system is. If CO2 levels are suspected to be too high, ventilation should be checked for poor design or problems / malfunctions as well as changes in the workplace layout.

Workers may experience respiratory problems if oxygen levels drop by about 1%. In the case of moderate or heavy-duty work, oxygen levels decrease as CO2 production increases with physical exertion.

Volatile Organic Compounds (VOCs)


Volatile Organic Compounds are released from solvents in paints, coatings, paint strippers, solvent containers, paint thinners, plastering materials, carpets, adhesives, photocopiers, ceiling or wall tiles, air fresheners, cleaners, organic solvents, fabric softeners and cigarette smoke.

Health hazards

In conditions of reduced exposure, symptoms include fatigue, headache, drowsiness, dizziness, weakness, joint pain, blurred vision, eye and skin irritation, and general discomfort. Increased exposure levels cause workers to experience respiratory discomfort, chest tightness, nausea, confusion as well as unpleasant odors.

Some hypersensitive individuals may experience severe reactions when exposed to very low concentrations.


The following must be checked for potential VOC release:

  • New building materials.
  • New furniture and carpets.
  • Use of cleaners, solvents (audit of the Safety Data Sheets).
  • Use of local exhaust ventilation in chemical storage areas.
  • Possibility of contaminating other workplaces in a building through the air conditioning/ventilation system.
  • Possibility of VOC entry into the building from external sources through air intake.

Further information on the VOC emission levels of carpets, building materials and furniture should be required from the importers/ manufacturers/ suppliers of these products and evaluated accordingly.

Carbon Monoxide (CO)


Carbon Monoxide (CO) is a colorless, odorless, toxic gas. It is produced from incomplete combustion in boilers, smoke from tobacco products and from motor vehicle exhausts.

Health hazards

Carbon monoxide impairs the ability of blood to absorb oxygen from the breathable air. At low concentrations (more than 9 ppm), carbon monoxide can cause headache and fatigue. At higher concentrations CO can cause poisoning or even death.


  • Are there any potential sources of CO inside the building?
  • Is it possible for CO to enter the building from external sources?

The American Conference of Governmental Industrial Hygienists has set the limit of 25 ppm (29 mg/m3) for 8 hours of exposure to carbon monoxide.

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