Air quality measurements information

CO Carbon monoxide

CO₂ Carbon Dioxide

Carbon dioxide (CO₂) is a colourless, odourless gas naturally present outdoors at about 400 ppm and produced indoors by breathing, combustion and some appliances. Concentrations above 1 000 ppm indicate insufficient ventilation and can lead to drowsiness, headaches and reduced concentration. Good CO₂ control is a reliable proxy for fresh-air supply and overall indoor-air quality.

If CO₂ levels are high, take the following precautions:

• Increase ventilation by fully opening windows or switching on mechanical/HRV systems.
• Take regular breaks outdoors to get fresh air.
• Reduce the number of people or the time they spend in the room.
• Avoid activities that add extra CO₂, such as intense exercise or burning candles.
• Watch the CO₂ monitor and ventilate again whenever the reading exceeds 1 000 ppm.

Radiation Background radiation

Background radiation (gamma radiation) is natural ionising radiation from cosmic rays and terrestrial radionuclides. Typical outdoor levels are around 10–20 µR/h. Short-term exposure to moderate levels is generally harmless, but prolonged exposure above 100 µR/h increases long-term cancer risk.

If radiation levels rise above normal, follow these precautions:

• Move indoors or to a shielded area (concrete walls or a basement).
• Close windows and vents, set HVAC to recirculation.
• Limit the time spent in high-radiation zones.
• Monitor official guidance and radiation reports.
• Avoid consuming local food and water until levels return to normal.

Humidity

Relative humidity shows how much water vapour the air holds compared with the maximum it could hold at the same temperature. Indoors the optimal range is 40–60 %. Below this the air feels dry and can irritate skin and airways; above it the room becomes stuffy and promotes mould growth and heat stress.

If humidity falls below 40 %, take the following measures:

• Run a humidifier or place open containers of water near heat sources.
• Ventilate briefly but regularly to bring in moister outdoor air.
• Drink enough water and use skin moisturisers or saline sprays for mucous membranes.
• Add indoor plants that release moisture.
• Avoid excessive heating ‒ warmer air dries out faster.

If humidity rises above 60 %, take the following measures:

• Ventilate more often or use a mechanical ventilation/AC system with dehumidification.
• Switch on bathroom and kitchen exhaust fans while cooking or showering.
• Avoid drying clothes indoors ‒ or do so in a ventilated room.
• Use a portable dehumidifier in persistently damp areas.
• Monitor humidity and ventilate again if readings stay high.

Noise Avg. Average noise (Leq)

Average noise (Leq) represents the mean sound-pressure level over the measurement period and is expressed in decibels (dB). Prolonged exposure to average levels above 70 dB can lead to fatigue, sleep disturbances and, over years, hearing loss. Typical quiet rooms are 30–40 dB; normal conversation is about 60 dB; busy streets reach 70–80 dB.

If the average noise level exceeds 70 dB, take the following precautions:

• Close windows and doors or move to a quieter room.
• Use earplugs, noise-cancelling headphones or earmuffs.
• Increase distance from the noise source; each extra metre reduces the level by ~6 dB.
• Soften room acoustics with carpets, curtains and acoustic panels.
• Limit the time spent in noisy areas and schedule quiet breaks.

Noise Max. Maximum noise (Lmax)

Maximum noise (Lmax) is the highest instantaneous sound level recorded during the measurement window, expressed in decibels (dB). Short peaks above 85 dB can start to damage hearing if they occur often, and single blasts above 120 dB may cause immediate pain or injury. Monitoring Lmax helps to catch those sudden loud events that the average level (Leq) may hide.

If maximum noise levels exceed 85 dB, take the following precautions:

• Wear earplugs or noise-cancelling earmuffs when peaks are expected.
• Reduce the source volume or switch off alarm tones/beeps.
• Add soft furnishings or acoustic panels to absorb sudden sounds.
• Keep a safe distance: every extra metre cuts peak level by about 6 dB.
• Enable alerts on the noise monitor to warn you of dangerous spikes.

PM10 Particulate matter with diameter ≤ 10 µm (PM10)

PM 10 (Particulate Matter 10) consists of atmospheric particles with a size of up to 10 µm, including dust, soot and other pollutants. They can cause health problems by affecting breathing and contributing to respiratory diseases. Sources include industrial emissions, road dust and fuel combustion.

If PM10 levels are high, take the following precautions:

• Limit the time spent outdoors.
• Avoid intense physical activity, especially for people with respiratory problems.
• Keep windows and doors closed to reduce indoor pollution.
• Use well-filtering masks if necessary.
• Monitor air-quality information and heed local health-authority advice.

PM2.5 Particulate matter with diameter ≤ 2.5 µm (PM2.5)

PM 2.5 is atmospheric particles with a size of up to 2.5 micrometers, which include dust, soot, and smoke. They can be harmful to health, causing breathing problems, allergies, and cardiovascular diseases. Sources of PM 2.5 include industry, transportation, and household emissions. Monitoring and reducing their levels are important for health and clean air.

If PM2.5 levels are high, take the following precautions:

• Stay indoors with good ventilation.
• Avoid outdoor physical activities.
• Keep windows and doors closed.
• Use face masks with good filtration.
• Monitor the air quality forecast.

Pressure Atmospheric pressure

Atmospheric pressure is the weight of the air column pressing on the Earth’s surface, expressed here in millimetres of mercury (mmHg). The long-term mean at sea level is ≈ 760 mmHg. Barometric swings reflect weather systems: falling pressure often precedes clouds and storms, while rising pressure brings clear, calm conditions. Sudden changes can affect well-being, causing headaches, dizziness or fluctuations in blood pressure in sensitive people.

If pressure drops below 750 mmHg, consider the following advice:

• Stand up slowly to avoid dizziness and faintness.
• Stay hydrated; warm drinks can help improve circulation.
• Ventilate the room for fresh oxygen-rich air.
• Rest if you feel lethargic or have a weather-related headache.
• Discuss any persistent symptoms with your doctor, especially if you take cardiovascular medication.

If pressure rises above 770 mmHg, take these measures:

• Limit strenuous outdoor activity if you have hypertension.
• Maintain comfortable indoor humidity to ease breathing.
• Drink plenty of water and eat light meals.
• Reduce caffeine and alcohol, which can elevate blood pressure.
• Regularly monitor your blood pressure and follow medical advice on medication adjustment.

Temperature

Air temperature is a fundamental comfort parameter that influences thermal sensation, metabolism and safety. Indoors the generally comfortable range is 20 – 25 ℃; outdoors it varies with clothing, wind and humidity. Extreme cold risks hypothermia and frostbite, while high heat can lead to dehydration, heat exhaustion or heat-stroke.

If temperature falls below 0 ℃, follow these precautions:

• Dress in layers, including hat and gloves; keep extremities dry.
• Limit time outdoors and take warm-up breaks indoors.
• Stay active to maintain body heat, but avoid sweating.
• Protect electronic devices and batteries from freezing.
• Watch for signs of hypothermia (shivering, slurred speech) and seek warmth immediately.

If temperature rises above 30 ℃, take the following measures:

• Drink water regularly; avoid sugary and alcoholic drinks.
• Limit strenuous activity during the hottest hours (11 am – 4 pm).
• Wear light-coloured, loose, breathable clothing and a wide-brim hat.
• Use fans or air-conditioning and ventilate at night when it is cooler.
• Check on vulnerable people (children, elderly) and pets; never leave them in parked cars.