Discovery zone

In this hub you can:

  • learn about air quality and how it affects climate change
  • see how we measure air quality and how bad air can harm people's health
  • find out what you can do to help clean up the air in Lewisham and reduce your impact on the climate

Types of pollution

In Lewisham, there are three types of pollution. Select each one to learn more.

  • O3

    Ozone

    State:

    Gas

    Where it comes from naturally:

    • upper air ozone made by chemical reactions with oxygen and sunlight

    Where it comes from humans:

    • cars
    • consumer products
    • paints evaporating

    What it is and its effects:

    Upper air ozone is made by chemical reactions with oxygen and sunlight. 

    Ozone is a gas found high up in the atmosphere, where it helps protect us by blocking the sun’s harmful ultraviolet rays. 

    At ground level, ozone can be harmful to breathe. It can irritate the lungs and make it harder to breathe, especially for people with asthma or other breathing conditions. 

    Ground‑level ozone forms when different types of air pollution mix and react in sunlight. Hot, sunny weather speeds this up, so ozone levels are usually higher on warm summer days. 

    Ozone also reacts with nitric oxide (NO), a gas commonly found near busy roads. Because NO breaks down ozone, levels of ozone can sometimes be higher in rural areas than in cities.
  • PM2.5

    Particulate matter

    State:

    tiny particles and liquid drops

    Where it comes from naturally:

    • volcanoes
    • desert dust
    • wildfires
    • pollen
    • sea salt

    Where it comes from humans:

    • cars
    • burning wood and other fuels at home

    What it is and its effects:

    Particulate matter is the name for tiny particles and liquid droplets that are in the air. They are so small we can't see them. Because they're so small, they stay in the air, and we can breathe them in through our noses and into our lungs.

    Different sizes of particles:

    • PM10: Particles smaller than 10 microns (less than a millimetre). Bigger particles get stuck in our noses or throats because of the tiny hairs in our noses.
    • PM2.5: Even smaller particles, less than 2.5 microns. These can go deep into our lungs and cause harm. People with heart or lung problems might feel worse because of this kind of pollution. These tiny particles can also get into our blood and affect other parts of our body.
  • NO2

    Nitrogen dioxide

    State:

    Gas

    Where it comes from naturally:

    • lightning
    • volcanoes
    • bacteria

    Where it comes from humans:

    • cars
    • heating systems like gas central heating in homes

    How it forms and its effects:

    Nitrogen dioxide is made when fuel is burned. It is harmful for people to breathe, especially those with heart or breathing problems, as it can worsen their condition.

    What it is:

    Nitrogen dioxide (NO₂) is part of a group of gases called nitrogen oxides. It contains two oxygen atoms, while nitrogen oxide (NO) contains just one. 

    Nitrogen oxide (NO) is harmless and invisible. But once it’s released into the air, it quickly reacts with oxygen and turns into nitrogen dioxide (NO₂). This is the form that can irritate our lungs and pose a health risk, especially for people with asthma or other breathing conditions. 

    So even though NO itself isn’t harmful, it changes rapidly into NO₂, which is the pollutant we need to reduce.

Where does this pollution come from?

Air pollution comes from both human activities and natural sources, such as wildfires or dust blown by the wind.

 

Some examples of man‑made activities that contribute to air pollution include:   

  • Road vehicles

    (cars and trucks)

  • Construction

    (building houses, offices)

  • Waste disposal

  • Agriculture

    (farming)

  • Burning of solid fuels

    Such as wood at home

  • Burning of fuels for industry

Health impacts of air pollution

Air pollution affects different people in different ways.

  • Irritations

    People who don't have health problems usually won't notice air pollution. But if the air pollution gets bad, even healthy people might get a sore or dry throat, sore eyes, and a tickly cough.

  • Stress on the body

    People who have heart or lung problems are more likely to feel sick or need treatment when the pollution levels are high. They should follow their doctor's advice.

  • Asthma

    Kids with asthma should always have their inhalers and other usual medicines with them, and make sure their teachers know about their asthma and what to do.

How do I know if air pollution is bad?

Air pollution is measured and monitored within the UK using a scale from 1 to 10.

Low
1
2
3
Mid
4
5
6
High
7
8
9
Very High
10

Measuring air pollution

There are a number of ways to measure what is in air. We will focus on three main techniques for measuring these pollutants.

  • Automatic monitoring

    How automatic monitoring works

    Automatic monitoring is the most advanced way to check air pollution, but it’s also the most expensive! There are 7 places in Lewisham that use this method. 

    What it does:

    • these sites work all day and night, measuring pollutants continuously.
    • they pull in air and measure how much pollution is in it.

    Different machines for different pollutants

    Each machine measures a different pollutant. For example, a site might have:

    • one machine for measuring nitrogen oxides (NOx)
    • one for measuring ozone
    • one for measuring particles like PM10

    How we get the data

    A computer collects the data from these sites, allowing us to monitor pollution levels almost in real time.

  • Passive monitoring (non-automatic)

    How passive monitoring works

    Passive monitoring is a simple and cheap way to measure gas using diffusion tubes. It doesn’t need electricity or pumps like automatic monitoring.

    What it looks like:

    • diffusion tubes are small plastic tubes with one cap on top. You might see them strapped to lampposts!
    • they usually monitor for 2-4 weeks at a time.
    • under the cap is a mesh disc with a chemical that absorbs NO2 (a type of pollution).

    How it works:

    • to start, the bottom cap is removed to let air flow inside the tube.
    • after 2-4 weeks, the tube is closed and sent to a lab to see how much NO2 it absorbed.
    • when gases pass over the mesh, the chemical inside the tube changes.

    Comparison to automatic monitoring:

    • passive monitoring is cheaper but less accurate than automatic monitoring.
    • it doesn’t show day-to-day pollution trends as well as automatic monitoring does.

  • Sensors

    How air quality sensors work

    Air quality sensors are small, simple devices that use very little power. They can give us data every minute.

    Why they’re useful:

    They help us quickly find places where air pollution is high.

    Checking the data:

    The data from these sensors needs to be compared with data from more advanced methods, like automatic monitoring sites, to make sure it's accurate.

Why is weather important?

  • Wintertime

    During the winter, the air pollution gets worse because of the weather. There is less sunlight and it's colder, so the pollutants in the air stay closer to the ground where people can breathe it in. Also, in winter, more people drive cars and use heaters, which makes the air even dirtier.

  • Summertime

    In the summer, when it's hot and sunny and there isn't much wind, a gas called ozone can form. This happens because the sunlight helps other chemicals in the air, like nitrogen dioxide, mix and create ozone.

Air quality overview

Breathing and oxygen

  • humans and other animals use lungs to breathe.
  • air is a mix of gases, with oxygen being crucial for survival.
  • without oxygen, we couldn’t survive, so clean air is really important.

Air pollution

  • poor air quality or air pollution, indicates dirty air.
  • dirty air has bad stuff that can harm our health and damage the environment.
  • polluted air can also hurt animals and plants.

Causes of air pollution

  • most air pollution is caused by human activities such as driving, construction and other various actions
  • pollution can be visible (smoke), invisible, smelly (car exhaust) or have no smell and is harmful for all living beings.

Helping the air

  • the good news is that our air is getting cleaner but there’s still more to do to make the air even better.