Particulate matter

This is made up of lots of different sorts of things, including vehicle exhausts, smoke or soot from fires, bits of metal from engines, bits worn from brakes and tyres and dust and waste from the road. Particles can also be formed from chemical reactions in the air.

Particulate matter causes the most damage to health. When we breathe in, the larger particles stick in our throat and windpipe. The smallest particles go deep down into our lungs and can pass into our blood. Once in the blood, they can be transported around the body and they can be found in different organs.

Most of the particulate matter in the city, especially close to roads, comes from traffic. Burning wood and coal in domestic fires can also produce high levels of particulates. Particles can also be emitted to the air from industry and agriculture.

Nitrogen dioxide

The gas, nitrogen dioxide, is another type of air pollutant that can affect our health. This is released into the atmosphere when fuels are burned and diesel cars and vans are the largest source. 

Transport is one of the largest sources of air pollution and contributes on average to approximately 80% of Nitrogen Oxides (NOX) emissions in areas where the UK is exceeding NO2 limits near roadsides

How does air pollution affect our health?

Poor air quality affects everyone. The diagrams below show how air pollution can affect our bodies. It is linked to heart disease and worsens breathing problems. Between 28,000 – 36,000 deaths per year have been attributed to long-term exposure to poor air quality in the UK

Air pollution has the greatest impact on children, the elderly and people with existing heart and lung conditions. It can increase the risk of needing to be admitted to hospital with heart and lung conditions and contributes to people dying young – before their time.

Children are particularly vulnerable as their lungs are still developing. For their size, they breathe more air per minute than an adult – and buggies and prams put them at the level of car exhausts! Air pollution can stunt lung development, and can affect children for life.

Air pollution is the largest environmental public health risk in the UK and is directly linked to:

  • Cancer
  • Obesity
  • Respiratory diseases (pneumonia, asthma, chronic bronchitis)
  • Cardiovascular diseases (chronic heart disease (CHD), strokes)

According to Public Health England, between 2017 and 2019 mortality rates for those under 75 years of age directly attributed to respiratory disease were:

  • 34.2 per 100,000 for England
  • 65.5 per 100,000 for Liverpool

Estimates suggest that approximately 230 deaths per year are linked to man-made air pollution in Liverpool

Diagram showing main sources of pollution including transport and industry

Sources of Air Pollutants

Air pollution is primarily caused by:


  • The combustion of fossil fuels in road vehicles
  • Industrial processes
  • Domestic heating
  • Power generation


These can give rise to several pollutants including:


  • Nitrogen Oxide (NO) & Nitrogen Dioxide (NO2) (collectively known as NOx)
  • Sulphur Dioxide (SO2)
  • Particulate Matter (PM)