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Testing home air quality, temperature, and humidity

A pleasant home interior with open windows

A simple, low-cost way to investigate the health of your home and make decisions about home improvements.

Home monitoring — testing air quality, temperature and humidity — is a simple, low-cost way to investigate the health of your home. It can tell you a lot about your home’s air quality, how quickly it loses heat and where from, and help identify issues with damp and mould. This information can help you make decisions about home improvements like draught-proofing, ventilation, insulation, and heating systems.

You can monitor lots of different things in your home including:

You can buy or borrow simple monitoring devices that measure some or all these things. They all look a little like this:

A black device with a screen showing a reading of 541 parts per million CO2, sitting on a wooden surface in front of a white wall.

Why check indoor air quality, temperature, or humidity?

Most people spend a significant part of their day indoors, so maintaining a comfortable temperature, healthy humidity levels and good air quality is important for your health and the health of your home.


A healthy and comfortable room temperature is between 18 and 21oC. Find out why keeping your home warm is important for your health.


Relative humidity means the percentage of water vapour in the air. You should aim for between 40 and 60%.

High levels of humidity in your home can cause condensation, damp, and mould which damages your home, furniture and health.

Humidity that is too high or low can also encourage the growth of bacteria, viruses and mites and make you more prone to respiratory infections, allergies, rhinitis and asthma.

Air quality

Poor indoor air quality is linked to a range of illnesses including asthma, pneumonia, lung cancer, chronic obstructive pulmonary disease and cardiovascular disease. Recent research has shown it has the potential to damage every organ in the body.

Around 3.8 million people die each year from exposure to indoor air pollution.

Indoor air pollution comes from many sources like:

It’s important to make sure your home is well ventilated so that these harmful pollutants can get out and be replaced by fresh air.

Using home monitors

There are different ways to monitor your home, depending on what you want to measure and your budget.

The types of monitor that you could use include:

Although specifically measuring air pollutants like HCHO and TVOCs can be useful, you can also get a good idea of air quality with simpler monitors that measure CO2 or humidity, as these show you how well ventilated your home is.

Most monitors don’t store information, so to take readings over a period, you’ll need to record them in a log. More sophisticated monitors can collect and store data remotely, and some can be operated remotely too.

Testing the air quality, temperature, and humidity of your home

It’s a good idea to take readings in various rooms in your home at different times such as:

We’ve created a table to help you record your readings. Download it here.

Understanding your results

Compare your readings to the following recommendations for a healthy home:

TemperatureFrom 18oC to 21oC
Humidity From 40% to 60%
CO2below 1,500ppm (800ppm for offices or non-domestic buildings)
TVOCsunder 0.25 ppm, or 500 µg/m3

If the temperature of your home changes a lot during the day, this indicates poor insulation. This means lots of heat is lost from your home, which can cause you to waste energy and cause bills to be high.

Don’t worry if the other readings listed above go up and down. There’s many reasons why these things might fluctuate, for example:

A well-ventilated home will regularly exchange the air inside with fresh air, so provided your readings quickly come back down to healthy levels, it’s nothing to worry about. If your readings are very different from the recommendations above, it’s a good idea to make some changes.

Taking action

The information you gain from monitoring your home can help you identify issues and make improvements. These will most likely involve changing how you heat or cool your home, increasing ventilation, and reducing sources of unwanted gases, chemicals, and particles.  

For example, if you’ve noticed that your home is regularly colder than recommended, or that the temperature fluctuates a lot, you might think about installing draught-proofing or insulation. If these problems happen in some rooms but not others, this tells you which rooms to prioritise.

If you see high levels of humidity in your kitchen or bathroom you might consider installing extractor fans or opening windows after cooking or washing.

If you see high levels of air pollution after cooking on a gas stove or using a log burner, you might think about switching to an electric or induction hob, using a different heating system, or improving your home’s ventilation.

These are just a few examples of actions you could take.

For more information on ventilation and home energy-efficiency, check out our energy advice pages.

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