Types of air pollution

According to the British Lung Foundation, the most abundant and harmful pollutants include :

Nitrogen dioxide (NO₂)

What is it?

Nitrogen dioxide is a gas and is a major component of urban air pollution episodes.

Where does it come from?

Man-made sources of nitrogen oxides, including nitrogen dioxide, are vehicles, power stations and heating. Diesel vehicles are major contributors in urban areas. Roadside levels are highest where traffic is busiest.

How does it affect your lungs?

High levels of NO₂ can irritate and inflame the lining of your airways, causing a flare-up of asthma or COPD and symptoms such as coughing and difficulty breathing.

Children and older people are also more affected and more likely to develop a respiratory infection, or react to an allergen (any substance that triggers an allergic reaction, such as pollen).

Ozone (O₃)

What is it?

Ozone is a gas composed of three atoms of oxygen. In the upper level of the Earth’s atmosphere, it absorbs harmful ultraviolet radiation.

Where does it come from?

Near the ground, ozone is made by a chemical reaction between the sun’s rays and organic gases and oxides of nitrogen emitted by cars, power plants, chemical plants and other sources.

Levels of ozone tend to be highest in the spring and summer and lowest in the winter. Ozone reaches its peak concentration during the afternoon. Levels are often higher in the country than in towns. Ozone is a major component of summer air pollution episodes.

How does it affect your lungs?

Ozone can irritate the airways of healthy people and people with lung conditions. High levels can cause you discomfort when you breathe, reduce your lung capacity (the amount of air your lungs can hold) and trigger asthma symptoms.

If you have a lung condition, high levels of ozone can cause you to have difficulty breathing, to wheeze and to cough. People with asthma may need to use their inhaler more.

When there are high levels of ozone, more people are admitted to hospital with asthma-related health problems and COPD symptoms, and there is a greater risk of illnesses like pneumonia and bronchitis.

Sulphur dioxide (SO₂)

What is it?

Sulphur dioxide is a colourless gas, with a pungent, suffocating smell. It’s produced by burning sulphur-containing fuels such as coal and oil. This includes, vehicles, power generation and heating.

Where does it come from?

Most sulphur dioxide comes from electric industries that burn fossil fuels, and also from petrol refineries and cement manufacturing. It can be transported over long distances and contributes to the formation of ozone.

How does it affect your lungs?

Sulphur dioxide can irritate the lining of your nose, throat and lungs. It can cause coughing and tightness of your chest, as well as a narrowing of your airway that will reduce the flow of air to your lungs. It inflames the airways, causing coughing and more mucus. It makes conditions like asthma and COPD worse. It makes people more prone to chest infections.

People with asthma are much more sensitive to sulphur dioxide than those who do not have asthma. They may find breathing more difficult and have flare-ups when concentrations of sulphur dioxide are high.