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Indoor environment monitoring: How sensors can help keep staff safe and well

Providing staff with a comfortable and safe working environment is a fundamental duty of any employer but has increasingly come under the spotlight since the start of the Covid-19 pandemic.

Where people may once have taken it for granted that their offices were a safe space, our increased awareness of ventilation and the transmission of germs mean many staff, and indeed employers, are more conscious than they have ever been about their work environment.

For large organisations with multiple offices or buildings it can be hard to know exactly what conditions are like across their entire estate, which is where indoor environmental sensors can play a key role. Connected to IoT cloud systems, sensors can provide real-time data on a range of measures ensuring any issues can be dealt with quickly and efficiently, keeping staff safe and comfortable.

This article will look at the different parameters that can be captured by indoor environmental sensors and explain exactly what it is that the sensors are measuring.


Air quality

There are a range of different air quality indicators that can be measured by sensors – something that is particularly important in closed spaces like offices or factory floors, where the air tends to be continuously recycled.

At best, high concentrations of these indicators may lead to a reduction in employee productivity and uncomfortable conditions for staff, at worst they could cause serious health problems.

In the UK many of the parameters below are governed by Workplace Exposure Limits (WELs), determined by the Health and Safety Executive, with breaches of these leaving the employer liable to large financial penalties.


Carbon dioxide (CO2)

Carbon dioxide is naturally present, in very low concentrations, in the air we breathe and is not harmful at low levels. High concentrations, however, can cause headaches, dizziness, confusion and even loss of consciousness, which is why it is classed as a ‘substance hazardous to health’ under the Control of Substances Hazardous to Health Regulations 2002 (COSHH).

It is a colourless and odourless gas, when at room temperature, making it impossible to know whether concentrations are high without some kind of monitoring device.

It is usually measured and reported in parts per million (PPM). Healthy, fresh air would typically show around 400PPM. Workplace exposure limits (WELs) are 5000ppm for 8 hours or more and 15000ppm for 15 minutes or more.

Volatile Organic Compounds (VOCs)

Volatile organic compounds are gases that are emitted into the air from products or processes and are most commonly found in things like paints, solvents, aerosols, disinfectants and adhesives.

They are the chemicals responsible for the smell you may experience when you buy a new car or new furniture – although manufacturers are becoming increasingly aware of the need to reduce the usage of them.

Exposure can cause headaches, dizziness, nausea and coughing, and some longer-term cases of exposure can be linked to cancer.

Sensors use a variety of measurements for VOCs. They may use an index measurement of between 1 and 500 to report VOCs in the air – the lower the value, the better, or they can report the levels in micrograms (one-millionth of a gram) per cubic meter of air or µg/m3 or parts per billion (PPB).

Workplace exposure limits vary depending on the particular compound.

Particulate Matter (PM)

Particulate matter consists of microscopic particles that are so small they can be inhaled, potentially causing health problems – for example pollen, mould and metals, or dust from things like grain, asbestos, wood or flour.

Particles come in varying sizes and are measured in micrometre units – 10, 4, 2.5 and 1. To put this into context, the average human hair is about 70 micrometres in diameter.

The tinier the particles, the more likely they are to cause damage as they can be more easily inhaled deep into the lungs or even end up in the bloodstream. The health effects of exposure to some PM – for example asbestos dust – can take many years to develop, but short-term effects, particularly from PM 2.5, can include bronchitis and asthma attacks. Those with pre-existing heart and lung conditions are particularly at risk.


Room conditions

As well as air quality, sensors can be used to measure a number of the other important factors which contribute to comfortable room conditions. As with the air quality parameters mentioned above, keeping a track of the following issues can help to ensure employers are providing comfortable, safe environments that people actually want to work in.

Light intensity

This is measured in LUX and tells you how bright an environment is. If lighting is too bright it can cause headaches and vision issues. If it is too dark it could cause safety concerns, but also headaches and eye strain if staff are struggling to see.

The recommended LUX levels in an office environment are anywhere between 300-500 LUX, but this will change depending on the setting.

Sensors can typically read up to 20,000 LUX.


Sound levels

Sound monitoring can be used to detect if somebody has entered an area, due to a change in sound level, or if an environment is deemed too loud and exceeds required levels.

Sound is measured in decibels (dB).

The Health and Safety Executive (HSE)’s Noise Regulations require employers to take specific action – for example, providing ear protection – at certain levels but, typically, anything over 80 dB would be a cause for concern, depending on the length of exposure to it.


Measured in degrees Celsius or degrees Fahrenheit, the temperature of a workplace can be one of the biggest factors affecting staff comfort and safety.

There is no legal maximum office temperature in the UK.

Guidance from the Health and Safety Executive (HSE) says that workplaces should aim to be no cooler than 16oC, or 13oC if much of the work involves “rigorous effort”, but there is no guidance for top temperature. This is due to the very high temperatures that can be found in workplaces such as kitchens and foundries, where it would not be reasonable, or possible, to expect them to be cool.

The HSE website also states that ‘thermal comfort’ is about more than just the ambient temperature in the room and that employers should also look at other factors including humidity, radiant temperature from any equipment in the room and air velocity.



Humidity refers to the amount of water vapour or moisture in the air. It is usually measured as a percentage.

High humidity levels can make it very uncomfortable for staff, leading to feelings of lethargy and low energy. They can also make it easier for bacteria to spread, particularly respiratory infection.

Humidity can also be damaging to machinery and equipment, and cause mould to grow.


If you’re interested in finding out more about monitoring room conditions, contact our IoT business development team to see how we can support you.

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