It is desirable that around 15 – 20 m³ of fresh air reach each employee per hour.
Good ventilation prevents indoor air from becoming uncomfortable for employees. Factors such as building materials, size and depth of space, type and location of windows, maintenance and type of ventilation systems can make a significant difference.
In order for employees to feel the temperature is appropriate, there must be a balance between the heat generated in the body and the heat it gives off. The body's heat production depends on physical exertion. In hard work, it is approximately three times higher than in light work. Sedentary jobs make greater demands than other jobs on air temperature being appropriate because in sedentary situations people are more sensitive to temperature changes.
Too cold
If the workenvironment is too cold, the body reacts by increasing muscle tension. In doing so, the metabolism increases and the body temperature remains stable.
It becomes more difficult to move the fingers, work speed decreases and the risk of mistakes increases.
Too hot
In general, people feel that the air quality is worse when the temperature is too high.
If it gets too hot in the work area, muscles relax and sweating increases. As soon as the temperature is a few degrees above what is considered comfortable, many people experience drowsiness.
Mental and physical skills become impaired. The likelihood of mistakes, discomfort and headaches increase.
Criteria for temperature
A suitable temperature for sedentary work is considered to be 18°–22°C, but for jobs where work is performed standing without much movement, the comfort criteria is 16°–18°C.
Some jobs may require lower temperatures due to what is being produced, in which case staff must be provided with special clothing and working time limits in cooled workspaces.
Most people find it most comfortable if the temperature is 20-22°C when sitting still, but for some, higher temperatures or up to 24°C are comfortable.
It is important to keep in mind that people generally feel uncomfortable if the temperature changes during the day exceed 4°C. Temperature changes can be greater when there is a lot of electrical equipment present and where screens are not used to protect against the sun’s heat through windows.
Some areas in the workplace can become uncomfortably cold, for example where insulation is inadequate and in areas directly under the inflow of air from mechanical ventilation.
It is not advisable to have a work area near large windows. In winter, cold window panes can cause cold air to descend, leading to draft and cold feet.
If it is not possible to avoid having a work area by the window or exit door, measures should be taken to reduce the inconvenience that the location may cause, for example placing portable heaters under windows and erecting a windbreak at the exit door to reduce the inflow of cold air, not least if heated air is directed there.
Many things can cause drafts, including leaky windows and malfunctioning ventilation systems.
The reason why drafts often cause discomfort is the interplay of heat and movement in the air. Movement in the air is then greater than about 0.15 m/per second during sedentary work.
The moving air is colder than the air in the room. This also applies to slow air currents. It can also be cold radiation, for example if some heat is transmitted from people onto colder surfaces. If it is significant, people will feel like there is a draft, even though there is no noticeable movement in the air.
Drafts mainly affect those who work sedentary jobs. Over time, drafts can cause discomfort in the muscles and joints. In addition, constant cooling of the skin can reduce the body’s resistance to various pests.
Many measures can be taken to prevent drafts, such as sealing doors and windows, adjusting ventilation systems and maintaining them well, and designing housing in such a way that work spaces are not very large, as it is easier to control air quality in smaller spaces.
Humidity refers to the relative amount of water vapor in the atmosphere.
In general, humidity does not cause discomfort. However, low humidity can cause irritation to the eyes, lips and respiratory system, especially if the air is too hot and dusty. In addition, dry air contributes to the generation of static electricity.
To much humidity
Extremely humid indoor air can lead to the formation of damp spots on walls, windows and ceilings, which can contribute to mold formation. That increases the risk of discomfort due to allergies and intolerances.
In cold air there is almost no water vapor. Therefore, the humidity is low indoors during the winter. Cold air enters and is heated, if moisture (water vapor) is not added to it, the humidity of the air decreases.
Outdoor humidity can fluctuate throughout the year from about 20% relative humidity (rH) in winter to up to 60% in summer. Air humidity is measured and expressed as a percentage of the amount of moisture that can be in the air at a given temperature. As the temperature rises, the air can hold more water vapor.
Criteria for indoor air humidity
No criteria have been set for humidity in the workplace, but most people feel comfortable at 30-60% rH. To prevent too dry or too humid air, the humidity should be kept between 30-50% rH.
People usually do not experience changes in humidity if the temperature is between 20-22°C. If the temperature exceeds 24°C, most people will feel like the air is heavy and oppressive if the humidity is also above 50% rH.
With rising temperatures and increased workload, the effect of humidity on an employee’s well-being increases. The higher the humidity, the higher the temperature appears to be. If there is a lot of dust in the air, it may seem dry, even when the humidity is within normal limits.
Humidifier
Where humidifiers are used to increase air humidity, the upmost hygiene must be maintained, water must be renewed and the humidifier cleaned regularly to prevent the release of micro-organisms, including germs and mold.
Employees often feel better if they use small humidifiers on desks and in individual workplaces, but it is important to keep them clean so that they do not breed microbes and dirt.
Carbon dioxide (CO2) is a colorless, odorless and non-flammable gas with a slight acid taste at room temperature. It is a by-product of the combustion of substances as well as being formed by the metabolic processes of organisms, including humans. Since CO2 produced by exhalation, its concentration in spaces is used to indicate whether sufficient fresh air is supplied into the space. High concentration of carbon dioxide (>0.1%) may cause headache and fatigue, but nausea, dizziness and vomiting if it exceeds the exposure limit (>0.5%). If the concentration is very high (>1%) it can lead to loss of consciousness. In general, 20% of people complain of heavy air if the concentration of CO2 is over 0,1% (1,000 ppm).
According to the Building Regulations it must be ensured that the CO2 level in the indoor air will not normally exceed 0.08% and does not exceed 0.1% CO2 in the short term.
To prevent or reduce high levels of carbon dioxide in a building or a room, fresh air should be supplied to the area, for example by opening windows.
VOC is an abbreviation for the term “Volatile organic compound” and is a synonym for thousands of organic compounds that contain carbon and are mainly gases at room temperature. These volatile substances easily evaporate and assimilate into the indoor atmosphere.
The most common VOCs in the atmosphere that people are at risk of inhaling are acetone, arsenic, benzene, ethylene glycol, formaldehyde and hydrogen sulphide, many of which are carcinogenic.
VOCs are common due to the use of paints, varnishes, polish, detergents and fragrances but can also come from furniture, appliances and equipment.
Criteria for Volatile Organic Compounds (VOCs)
There are no approved exposure limits for VOCs or a total limit for volatile organic compounds (TVOC).
Generally, it is believed that if the concentration in the atmosphere is below 90 pbb (parts per billion) it is considered low, 90 – 150 ppb acceptable, 150 – 310 ppb on the verge of being bad and high if it exceeds about 310 ppb.
Good ventilation is the key to keeping the concentration of these substances down.
Fine dust in indoor air is classified into two types, PM2.5 and PM10, but PM is the English term for “particulate matter”.
It is a mixture of solid particles and droplets, for example dust, dirt, soot or smoke particles that are so large and dark that they are visible to the naked eye. Others are so small that they can only be detected under an electron microscope.
PM10: Inhalable particulate matter, usually 10 micrometers (0.01 mm) in diameter and smaller.
PM2.5: Fine inhalable particulate matter, usually 2.5 micrometers (0.0025 mm) in diameter and smaller. Since these particles are so small, it is easy to inhale them. Some particles are less than 10µg in diameter and can get deep into the lungs and some even into the bloodstream. Particles smaller than 2.5 µg (PM2.5) in diameter are the most dangerous.
Because these particles are so small, they are easy to inhale. Some particles are less than 10µg in diameter and can get deep into the lungs and some even into the bloodstream. Particles smaller than 2.5 µg (PM2.5) in diameter are the most dangerous.
Exposure limits according to the regulation (only available in Icelandic) on exposure limits and measures to reduce pollution in the workplace for very fine dust is 10 mg/m
3
There are no approved indoor limit values for PM10 and PM2.5, but some manufacturer’s testing equipment set the target >15/g/m3.
Good mechanical ventilation with clean filters and air purifiers contribute to dust-free indoor air.
When measuring indoor air quality (IAQ), an attempt is made to assess the temperature and its effect, as well as other environmental factors.
Measuring IAQ has several challenges. Measuring only individual factors, for example temperature, can give a misleading result because it says little about the overall effect.
Air speed, air humidity and the nature of the work, for example, can affect whether people find the temperature suitable.
It is important to do a pre-check and find out how employees experience the indoor air and what could be causing the discomfort they may complain about.
Examples of questions:
How is the workplace heated?
Are spaces free of drafts?
How well are the cleaning done?
How well does the ventilation work?
Are the spaces suitably large?
Are there different levels of physical exertion associated with jobs?
To what extent is it possible to control the effects of indoor air quality where the work is performed?
These are the main parameters that employers, Occupational Safety and Health (OSH) representatives and other employees can usually evaluate themselves. The following may be considered with professional assistance.
The following air quality factors are always taken into consideration when conducting a thorough indoor air quality inspection:
Air temperature
Heat radiation
Air speed
Humidity
Carbon dioxide (CO2)
Volatile Organic Compounds (VOCs)
Fine dust (PM2.5)
It is important that measuring devices are used in accordance with the instructions and are calibrated correctly. The location of the measurements, distance from the floor and time of day can greatly influence the results. The weather must also be considered and outdoor air measurements might be performed that can affect the result of indoor air measurements.
The location of a building affects the indoor air inside it. If there is a lot of heavily trafficked streets nearby, there may not be proper ventilation. This can be due to both pollution from emissions and the disturbance caused by traffic noise.
In buildings in such locations, the intake for mechanical ventilation shall be placed as high as possible to prevent problems related to indoor air.
Service provider
Administration of Occupational Safety and Health