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Measurement at home

Pollution monitor

How clean is the air near you?

  • This task measures dust and dirt and not greenhouse gases
  • How much does air cleanliness change with location?
  • How long does it take before you can detect dirt from the air?
  • How much pollution can you see, and how much is invisible?

Estimated time: can take up to a week before you see a result.
No prior knowledge needed.

Download the worksheet

Equipment required​

  • White plastic sheet/container or strong white card
  • Scissors and holepunch if using card
  • Pencil or pen to label card/plastic
  • Petroleum jelly (Vaseline)
  • Optional paintbrush
  • String or duct tape to hang sensors.


  • Choose locations that are easy for you to access and will not get in the way of, or be disturbed by people
  • Take care if using scissors not to cut yourself
  • Wash hands after touching petroleum jelly (so you don’t get it on anything else)
  • Take care not to damage the surfaces you stick monitors to

Step by step

Watch the video, then follow the instructions.

  1. Decide where you will place your pollution monitors. Find places where
    people won’t touch them, but where you can reach them easily.
  2. Make your monitors from either white/transparent plastic or thick white
    card. We used plastic lids from paper cups. If card, take care using
    scissors to cut 5 cm squares and add a hole if you plan to hang up using
    string. On each monitor write the location.
  3. Smear some petroleum jelly (like Vaseline) using your finger, or a paint
    brush, on the labelled side of monitors.
  4. Attach your monitors in location. Sellotape is probably not strong enough
    so use string or duct tape. Take care not to damage the surfaces you stick
    monitors to.
  5. Check the monitors closely daily. In time you will start to see dark specks.
  6. After 7-10 days carefully check all monitors for your report below...

Thoughts, tips and information

SI measurement units​

  • Second (s) for time (day = 86400 seconds)
  • Candela (cd) for light intensity to see and describe colour of pollution
  • Metre (m) for describing size of particles.

Challenge topics​

Climate measurement, measurement science, science observation, pollution

NPL is involved in measuring many types of pollution - including greenhouse gases your monitors cannot show.

Enter your results

Please enter your results in the table below. You may enter as many results as you like THOUGH PLEASE REFRESH THIS PAGE BEFORE EACH NEW ENTRY. Each time you Submit, you will send us the information written in the cells below.

* These are optional – the name is so we could mention you in the end of week report and the postcode is to see where people are taking part. We won’t use this information for anything else.