What are the main types of air pollution caused by transport?

The main pollutants of concern are nitrogen dioxide (NO₂) and particulate matter (PM). Carbon dioxide (CO₂) is a major greenhouse gas which causes climate change. Road transport is responsible for around 80% of the NO₂ measured at the roadside.

What creates more nitrogen dioxide – diesel or petrol engines?

Transport-related nitrogen dioxide is primarily emitted by diesel engines, although petrol vehicles produce a small amount. Electric vehicles produce none. HGVs, LGVs and buses make up around half the emissions, with private cars and taxis the remainder. Newer diesels produce much less NO₂ than older diesels.

What is particulate matter?

The term particulate matter refers to small particles of pollution in the air. The primary transport-related source is from vehicle exhausts, particularly diesel engines. Dust from brakes and tyre wear are also sources of particulate matter in all vehicle types, including electric vehicles.

Are there any other sources of air pollution?

Other significant sources of pollution include domestic solid fuel, aviation and shipping, and agriculture and industry in and beyond Wales, along with natural sources.

What is the impact of air pollution on health?

Short-term effects of air pollution include exacerbating existing heart and lung conditions, such as asthma and bronchitis. Most people will not experience short-term ill-health effects from exposure to the concentrations of air pollution typically measured in Cardiff, but susceptible individuals and population groups may be affected on occasions when air pollution is elevated. More vulnerable population groups include those with existing lung or heart conditions; and children and older people.

What about the long-term health effects?

Long-term effects of air pollution include increased rates of lung disease and cardiovascular disease (including heart disease and stroke) and cancer, and an association with type 2 diabetes. Polluted air is estimated to cause an equivalent of around 40,000 deaths each year across the UK, with average life expectancy estimated to be reduced by 7-8 months due to air pollution.

Is there any safe level of pollution?

There is no known safe level of exposure to particulate matter air pollution, or for short term exposure to NO₂. The effects of exposure increase the longer someone is exposed.

Is Cardiff the only city with this problem?

Cardiff is not the only place with this problem. 

In the UK, 28 cities have been identified with air pollution issues, including Cardiff, and we are all looking at how best to protect people’s health and clean up our air. A number of different approaches are being taken, but in both Wales and England there are overarching Government frameworks setting out some of the things we need to consider as solutions.

This is an issue in many countries around the world; in some developing countries the concentrations of pollution are orders of magnitude higher and hence significantly more dangerous; and there are many other countries in Europe facing challenges similar to us.

Why are we hearing more about air pollution now?

Air pollution concentrations in the UK have not been falling as fast as expected, or as required by law. In addition, the evidence linking long-term exposure to air pollution and health issues has been getting stronger over the last few years.

What can we do to reduce air pollution?

One of the main actions we need to take is to reduce the number of journeys taken in polluting vehicles in and around Cardiff.   Action also continues to be taken through existing regulatory frameworks to ensure other sources of air pollution are also controlled.

How can we reduce the number of journeys taken in polluting vehicles? 

There are a number of different ways to do this, which Cardiff Council and partners are currently reviewing. These include encouraging more people to walk, cycle and take public transport, especially for shorter journeys, and encouraging take up of electric vehicles.

What will be the impact on health of reducing air pollution?

By reducing air pollution the long-term health risks described above will get smaller for everyone living and working in Cardiff.  By shifting how we get around there are some additional benefits too, not just related to air quality.

What are the additional health benefits?

If you walk, cycle or take public transport you do more physical activity than getting straight into your car from your house. Levels of overweight, obesity and type 2 diabetes have been increasing over the past few years and store up long-term health issues. By supporting people to walk, cycle or take public transport we can help address this.  Healthier individuals are also better able to adapt to air pollution exposure, so they become less susceptible to the effects. Being physically active also reduces the risk of a host of other illnesses including cardiovascular disease, respiratory disease and dementia, and employees experience fewer sick days each year.

Being physically active can help with mental health too – you are less likely to experience stress and low mood if you are regularly active. Combining exercise with your daily commute is a great way to build it into your life.

Are there any other benefits?

Injury and death from collisions with cars may also reduce. The most common cause of death for children aged 5-14 is being hit by a car. 

Finally Wales, like the UK and most of the rest of the World, have committed to the Paris Agreement to reduce CO₂ emissions to help prevent global warming. Encouraging walking, cycling and public transport will help us reduce carbon emissions, leaving the world in a better place for us and future generations.

Where can I find out more about air pollution?

See Welsh Government’s plan, Tackling roadside NO₂ concentrations in Wales