Introduction to the programme
This module is one of three modules within this Air Quality Literacy Training Programme. You are required to complete all three modules.
Introduction to Air Quality
- Common air pollutants
- Health impacts
- Air pollution and inequality
Air quality at a regional and local level
- Regulations and standards
- What is happening locally
- Monitoring
- Air quality and net zero
How we can improve air quality and the benefits of clean air
- Air quality planning and policy
- Community engagement and communications
- Case studies
Once you have completed all three modules, you will be required to take an assessment on the topics covered.
Learning outcomes
By the time you complete this module, you should have a good understanding of:
- Common air pollutants, how they are categorised and the impact they have on people’s health and the environment.
- The main causes of pollutants and how this affects pollution concentration levels.
- Air pollution and the impact on inequalities.
Introduction to Air Quality
According to Defra…
Air quality is the term we use to describe how polluted the air we breathe is. When air quality is poor, pollutants in the air may be hazardous to people, particularly those with lung or heart conditions.
Clean air is a basic requirement of a healthy environment for us all to live in, work, and bring up families.
Department for Environment, Food and Rural Affairs (Defra) 2019
“The West Midlands will have air quality that is safe for all people, no matter where you live in the region, resulting in significantly improved public health and environmental outcomes.”
Vision statement from the WMCA’s Air Quality Framework
An overview of air pollution
There are several different air pollutants that affect the West Midlands and have implications for public health. The sources of this pollution differ between outdoor and indoor sources.
The diagram is describing what pollutants are in the air. These include NOx, aeroallergens, particulate, group level ozone, CO2 and NO2. These pollutants cause health impacts due to poor air quality which include premature death, chest pain, allergy sensitivity, development of exacerbated asthma, acute respiratory illnesses or COPD and cardiovascular disease.
Climate change also influences air quality as longer allergy seasons due to increase in CO2 influences the release of pollen and Ragweed. Changes in weather patterns (humidity, precipitation and wind) as well as rising temperatures increase the presence of pollutants.
The concentrations of each pollutant at a given location vary depending on the source of the pollution, local geography and meteorology.
Section 1 | Common air pollutants
Types of pollutants and the sectors causing these pollutants
Types of pollutants
We will now look at various pollutants and the key information associated with each one including the short- and long-term impacts.
Nitrogen Dioxide
Key information
A gas which is a by-product of combustion.
Sources and formation
Burning of fuel (cars, HGVs, buses, power plants). Formed from the reaction between nitrogen oxides (NOx) and other chemicals in the air.
Short-term impacts
Short-term exposure can lead to irritation of airways, respiratory symptoms, such as coughing and difficulty breathing, particularly for people that have asthma.
Long-term impacts
Long-term exposure to high levels of NO₂ can lead to the development of asthma and other respiratory diseases, reduced lung function and reduced lung development in children.
Links with other pollutants
Ozone is created when heat and light cause a chemical reaction between nitrogen oxide and volatile organic compounds.
Particulate Matter (PM10)
Key information
Particles with less than 10µm in aerodynamic diameter.
Sources and formation
Combustion (industry and domestic), road transport. Can be directly emitted or formed in the atmosphere (secondary).
Short-term impacts
Short-term exposure can lead to irritation of the eyes, nose and airways, respiratory symptoms, such as coughing and difficulty breathing, particularly for people that have asthma.
Long-term impacts
Long-term exposure to high levels of PM10 is linked to respiratory and cardiovascular morbidity, increase of mortality from cardiovascular and respiratory diseases, and lung cancer.
Links with other pollutants
Ammonia/secondary aerosol formation.
Particulate Matter (PM2.5)
Key information
Particles with less than 2.5µm in aerodynamic diameter.
Sources and formation
Combustion (industry and domestic), road transport. Can be directly emitted or formed in the atmosphere (secondary).
Short-term impacts
Short-term exposure can lead to irritation of the eyes, nose and airways, respiratory symptoms, such as coughing and difficulty breathing, particularly for people that have asthma.
Long-term impacts
Long-term exposure to high levels of PM2.5 is linked to respiratory and cardiovascular morbidity, increase of mortality from cardiovascular and respiratory diseases, and lung cancer.
Links with other pollutants
Ammonia/secondary aerosol formation, VOCs, SO2 and NO2.
Ozone
Key information
A gas formed in the atmosphere.
Sources and formation
Secondary pollutant, created by chemical reactions between other pollutants. Formed through chemical reactions between nitrogen oxides and Volatile Organic Compounds (VOCs) in the presence of heat and sunlight.
Short-term impacts
Short-term exposure can cause respiratory symptoms, such as coughing, throat irritation, wheezing, shortness of breath and discomfort when taking deep breaths.
Long-term impacts
Long-term exposure to ozone can cause worsening of asthma and can cause asthma development.
Links with other pollutants
NOx/NO2.
Volatile Organic Compounds
Key information
Gases emitted from natural and human sources.
Sources and formation
Vegetation, paints, aerosol sprays, disinfectants, air fresheners, engines. Emitted from natural sources (vegetation) or human made.
Short-term impacts
This is dependent on the VOC, but short-term impacts include irritation to the eyes, skin and respiratory tract, headaches and dizziness.
Long-term impacts
This is dependent on the VOC, but long-term impacts can include neurological effects (changes in hearing, balance), liver and kidney damage.
Links with other pollutants
Ozone precursor, PM reactions.
Ammonia
Key information
A gas emitted from primarily agriculture, so a pollutant that is more prevalent in rural areas.
Sources and formation
Agriculture (spreading of manure, slurries and fertilisers), waste and to a lesser extent road transport. Can also be released from other sources, such as industrial processes and biomass.
Short-term impacts
Primarily a concern for ecological impacts, however, higher levels of ammonia may cause irritation to the eyes, nose and throat.
High levels of ammonia may cause burns and swelling in the airways, lung damage and can be fatal.
Links with other pollutants
PM/secondary aerosol formation.
Sulphur Dioxide
Key information
A colourless gas with a strong odour.
Sources and formation
Power generation, industry and domestic heating. Formed through burning of fuel (or material) containing sulphur.
Short-term impacts
Short-term exposure to SO2 can cause respiratory problems and difficulty breathing, particularly for people with asthma.
Long-term impacts
Long-term breathing problems can be caused by long-term inhalation exposure to SO2.
Where air pollution comes from
PM emissions
Primary PM emissions have a wide spread of sources, ranging from commercial and domestic combustion (domcom), industrial production (indproc) and road transport (roadtrans). Commercial and domestic combustion are the largest source, making up 41% of direct PM2.5 emissions.
Notice the various PM10 emission sources below.
- 26% from Combustion in commercial, industrial, residential & agriculture
- 11% from Industry Combustion
- 25% from Industrial production process
- 8% from Solvent Use
- 19% from Road Transport
- 8% from Other transport and mobile machinery
- 2% from Water treatment disposal
- 3% Agriculture, forestry and landuse change
- 1% from nature
Notice the various PM2.5 emission sources below.
- 41% from Combustion in commercial, industrial, residential & agriculture
- 14% from Industry Combustion
- 5% from Industrial production process
- 6% from Solvent Use
- 19% from Road Transport
- 9% from Other transport and mobile machinery
- 3% from Water treatment disposal
- 1% Agriculture, forestry and landuse change
- 2% from nature
NO₂ emissions
Conversely, the details below shows that emissions from Nitrogen Dioxide (NO2) still have a significant range of sources, but the main source is from road transport, making up ~80% of NO2 emissions. These toxic gases are mainly emitted by high-temperature combustion which is why road transport and other forms of transport are the highest emitters.
Notice the main pollutant sources of NO2 emissions below.
- 82% Road Transport
- 8% Combustion in Industry
- 8% Other transport and mobile machinery
- 2% Combustion in Commercial, industrial, residential & agriculture
Spatial distribution of pollutants
Let’s take a look at the predicted annual average concentrations of NO2 and PM2.5 levels.
Map details the predicted 2021 annual mean NO2 concentrations based on WM-Air modelling. The map shows that the highest concentrations are mainly concentrated around main roads, such as the M5 and M6. Hotspots found in Solihull as well as along main road links.
This map shows the predicted 2021 annual mean PM2.5 concentrations based on WM-Air modelling. This indicates that pollution spreads further across the region as concentrations are high across birmingham, sandwell, walsall with areas in Wolverhampton, Dudley and Coventry.
Outdoor sources of air pollution
In the UK, the main sources of outdoor, ambient air pollution are transport, industry, domestic emissions and agriculture.
Emissions, such as NO2 in the West Midlands, are dominated by road transport. Within this, in typical urban UK environments, emissions are dominated by older diesel vehicles.
Not all pollution that is experienced in the West Midlands is produced in the region, with some coming from elsewhere in the UK and overseas. This is known as transboundary pollution and reflects the need for wider efforts beyond the West Midlands itself.
Pollutant emissions are impacted by the weather. In cold periods, increased domestic combustion and increased use of cars can increase emission of particulates and NO2. This is worsened by inversion layers, caused by atmospheric pressures, which occur during winter and trap in the pollutants.
High temperature and stagnant air in heatwaves can lead to increased ozone and particulate concentrations.
WM-Air researchers estimate that annually in the West Midlands, up to 2,300 premature deaths in the region arise from long-term exposure to particulate matter.
Manufacturing, agriculture and construction are also sources of pollution.
As a broader environmental issue, if the cement industry were a country, it would rank as the world’s fourth largest Greenhouse Gas emitter, just behind China, the US and India.
On air quality, this industry is the third largest source of industrial air pollutants such as sulphur dioxide.
Indoor sources of air pollution
It is a common misconception that the main sources of air pollution are all outdoor ones.
Indoor air quality is the air quality within and around buildings and structures and is affected by both actions that happen indoors and by the quality of the air outdoors.
A house showing the different types of indoor air pollution you can experience in your home. These include, outdoor pollutants, mould, household products, furniture, cooking and combustion sources (such as gas boilers/ hobs and solid fuel appliances like log burners).
For example, there are 1.5 million wood burning stoves in the UK, meaning that they are used by only a small fraction of the population, yet this contributes three times more primary small fine particulate pollution directly emitted than all traffic on our roads combined.
Specifically, the UK Clean Air Strategy (2019) states that 38% of primary particulate emissions come from burning wood and coal in domestic open fires and solid fuel stoves. Remember, primary emissions are those that are directly emitted to the air.
Pollution by domestic combustion
In the West Midlands, the domestic combustion sector contributes a small amount to total NO2 emissions but is responsible for a large proportion of primary (41%) PM2.5 emissions, primarily through domestic solid fuel combustion.
Emissions are generally highest in population centres as these combustion sources are used primarily for home heating, but the impact on PM concentrations is felt across the region. Population centres also generally have higher emissions due to the greater prevalence of cars and industry.
The highest annual average PM2.5 concentrations in the West Midlands are modelled in central Birmingham, Coventry, Sandwell and Walsall.
Emissions from domestic combustion are highly seasonal with emissions highest in the winter months when domestic heating is most heavily used.
The majority of the population typically spend most of their time indoors, at home, at places of work or study, or commuting, which is why it is important to tackle indoor pollution as we have greater exposure to indoor than outdoor air.
Section 2 | Health impacts
Outdoor air quality health impacts
Outdoor, ambient air quality is the measure of the condition of the air outdoors and is determined by the presence of various pollutants.
As you will have learnt already, key pollutants within the West Midlands are particulate matter (PM10 and PM2.5), nitrogen dioxide (NO2) and, increasingly, ozone (O3).
These pollutants can originate from both natural and human-made sources, including industrial emissions, household emissions, vehicle exhausts, construction activities and agricultural practices.
Secondary pollutant contributions also occur, for example with agricultural activities producing ammonia as well.
In the UK, it is estimated that air pollution’s estimated effect is equivalent to 28,000-36,000 deaths each year. In the West Midlands, this is estimated to be 2,300 premature deaths a year.
Some of the ways that outdoor air quality can affect people include the following.
Reduced quality of life
Poor air quality can lead to a decrease in overall wellbeing and quality of life.
Impaired lung development
Children exposed to air pollution may experience impaired lung development.
This can have long-lasting effects on their respiratory health and lung function throughout their lives.
Respiratory issues
Air pollution can cause or worsen respiratory conditions, such as asthma, bronchitis and chronic obstructive pulmonary disease (COPD).
The pollutants irritate the respiratory system, leading to symptoms like coughing, wheezing and shortness of breath, and increased susceptibility to respiratory infections.
Cardiovascular problems
Long-term exposure to air pollution has been linked to an increased risk of cardiovascular diseases, including heart attacks, strokes and hypertension.
The pollutants can enter the bloodstream, causing inflammation, oxidative stress and damage to blood vessels.
Cardiovascular problems
Long-term exposure to high levels of air pollution has been associated with increased mortality rates, particularly due to respiratory and cardiovascular diseases.
The pollutants can contribute to the development of chronic illnesses and exacerbate existing health conditions.
There is increasing evidence that long-term exposure to pollution can lead to certain types of cancer.
PM2.5 is the major pollutant of concern for mortality, but the other significant pollutants can also have a damaging impact.
The severity of health effects depends on several factors, including the concentration and duration of exposure, individual susceptibility and the specific pollutants present in the air.
As we will explore later, vulnerable populations are more exposed to these risks and impacts.
Case study
Read the case study below to learn more about the severity of air pollution.
Ella Kissi-Debrah died, aged nine, after an acute asthma attack in South London on the 15 February 2013.
She had more than 25 emergency hospital admissions over 3 years and in a landmark coroner’s report in 2020, Ella is the first person in the world to have air pollution cited as her cause of death.
Ella’s mother, Rosamund Kissi-Debrah, is driving the proposed Ella’s Law in the UK parliament which is a Clean Air (Human Rights) Bill aiming to protect the public against air pollution. The Bill would establish a right to clean air and set up a commission to oversee government actions and progress.
The Bill would force the government to bring air quality in every community to meet the minimum World Health Organisation (WHO) standards. Current UK air pollution targets set in the Environment Act 2021 are more lenient than those set out in the WHO standards.
This legal case, where Ella’s death was attributed to air pollution, demonstrates the complexity of linking the damaging effects of air pollution to health and mortality and exemplifies the need for estimations based on epidemiological evidence to generate statistics.
Indoor air quality health impacts
Some of the ways that indoor air quality can affect people include the following.
Cognitive and neurological problems
Certain indoor air pollutants, such as lead and carbon monoxide, can affect cognitive function and cause neurological problems.
Eye and skin irritation
Exposure to certain indoor air pollutants, such as pet dander and cleaning chemicals, can cause eye and skin irritation.
Respiratory problems
Exposure to airborne pollutants, such as mould, PM2.5, dust mites and VOCs, can cause or worsen respiratory issues such as asthma, bronchitis and allergies.
Cardiovascular problems
Exposure to certain indoor air pollutants, such as PM2.5 and carbon monoxide can increase the risk of heart disease, stroke and other cardiovascular problems.
Cancer
Long-term exposure to certain indoor air pollutants, such as radon and formaldehyde, can increase the risk of cancer.
It is important to maintain good indoor air quality to protect human health and wellbeing.
This can be achieved through regular ventilation, using air filters, reducing indoor pollution sources and using non-toxic cleaning and building materials.
The health benefits of improving air quality
Given the extent of the damaging impact on health that both indoor and outdoor air pollution can cause, it is no surprise that improving air quality would have far-ranging and extensive health benefits in the region.
Indoor
- Cleaner indoor air can improve cognitive function and productivity.
- Improved air can reduce the spread of airborne diseases.
- Protection against outdoor air pollutants, such as smog and wildfire smoke.
- Enhanced air can decrease the number of environmental triggers for conditions like asthma and allergies.
Ourdoor
Reductions in air pollution have been associated with improvements in the average life expectancy.
Reduced environmental damage: Lower air pollution will reduce environmental damage to plants and animals.
Reducing air pollution can improve crop and timber yields making food more accessible.
Cleaner air means fewer air-pollution-related health problems leading to potential savings for the NHS and social care.
Overall, improving air quality can have significant positive impacts on both human health and the environment.
Section 3 | Air pollution and inequality
Air pollution and health inequalities
The government has declared poor air quality as the largest environmental risk to public health in the UK.
The impact of poor air quality within the West Midlands is unequal and therefore those who have pre-existing and long-term health conditions, are disproportionally affected.
Below are the health effects of air pollution throughout the different stages of life.
Pregnancy
Children
- Asthma
- Slower development of lung function
- Development problems
- More wheezing and coughs
- Start of atherosclerosis
Adults
- Asthma
- Coronary heart disease
- Stroke
- Lung cancer
- Chronic obstructive pulmonary disease
- Diabetes
Elderly
- Asthma
- Lung cancer
- Diabetes
- Dementia
- Accelerated decline in lung function
- Heart attack, heart failure and stroke
Vulnerable populations, such as the elderly, children, pregnant people and individuals with pre-existing health conditions, are generally more susceptible to the adverse effects of air pollution.
In the West Midlands, it is also the case that those who live in poorer, more deprived areas - where typically residents are less likely to own a car - are more exposed to air pollution.
In 2019, a study of more than 300,000 people in the UK concluded that lung problems from poor air quality was especially pronounced in people with lower income.
Research carried out in London revealed that those from racialised communities were disproportionately more exposed to poor air quality.
Children are more vulnerable to air pollution because:
- They are shorter than adults so closer to the level of vehicle exhaust pipes.
- Young children breathe faster, so they take in more air relative to their body weight.
- As their bodies are still developing, exposure can lead to stunted lung growth.
Air pollution is not evenly spread across the region
Do you think that air quality is better or worse in the least advantaged areas of the region?
In 2005, the World Health Organisation (WHO) set guidelines that PM2.5 levels should not exceed 10 m-3.
WM-Air provides air pollution estimates of pollution concentrations at 1km resolution. When averaged to ward level, this data show annual average PM2.5 levels in 72 of the 192 wards within the West Midlands exceed 10 μg m-3.
1.2m people or circa. 40% of the West Midlands’ population live in wards exceeding PM targets of 10 μg m-3.
The least advantaged areas (highest IMD score) tend to have the worst air quality.
Case study
Read the case study below to learn more about air pollution and inequalities.
Awaab Ishak died in December 2020 from a respiratory condition caused by extensive mould in a one-bedroom flat in Greater Manchester. He was two years old.
Young children are more vulnerable to air pollution as their organs are still developing and they breathe more rapidly and are closer to the ground, where pollutants are more highly concentrated.
This, combined with poor living conditions where he was exposed to mould daily, which was not addressed by the housing provider, led to his death.
Senior Coroner, Joanne Kearsley said:
“Awaab Ishak died as a result of a severe respiratory condition caused due to prolonged exposure to mould in his home environment. Action to treat and prevent the mould was not taken. His respiratory condition led to respiratory arrest.”
Public health impacts of air pollution in the West Midlands
The WMCA has a population of approximately 2.9 million people, but life expectancy varies across the region, impacted in part by environmental pollution and air quality.
WM-Air researchers have developed the Air Quality-Lifecourse Assessment Tool (AQ-LAT), which uses local population and health data to better understand how the impacts of poor air quality are patterned across the region. The ward-level tool also enables appraisal of regional policies to understand where, and to what extent, health and monetary gains will be achieved from a given reduction in air pollution.
Applying the AQ-LAT, researchers have estimated that air pollution in the WMCA area contributes up to 2,300 early deaths each year. Pollution also increases the risk of long-term health conditions, including over 2,000 new asthma diagnoses among adults and children.
Reducing pollution to within WHO 2021 Global Air Quality Guidelines would gain ~130,000 years of life for the WMCA population over the next 20 years; with most benefits experienced in Birmingham and Sandwell. These improvements would generate economic benefit exceeding £3.2bn over the next 20 years.
WM Air-researchers have developed the Air Quality-Lifecourse Assessment Tool (AQ-LAT), which used local population and health data to better understand how the impacts of poor air quality are patterned across the region by ward level. The tool shows that in all Birmingham wards we can see the following benefits if air quality was improved;
- £36,906,000 10 year NHS cost savings
- £13, 093,000 10 year indirect cost savings
- £31,260,000 10 year Social care cost savings
- 2086 deaths prevented over 10 years
- 8913 QALY gains over 10 years worth £178,263,718
- 4645 asthmas cases prevented over years
- 1356 Coronary Heart Disease cases prevented over 10 years
- 276 Lung cancers prevented over 10 years
- 1118 stroke prevented over 10 years
2021 annual attributable incident cases were;
- annual asthma cases 874
- annual Coronary Heart Disease 262
- Annual lung cancers 59
- Annual strokes 231
Distribution of NHS costs;
- £935,974 Primary care costs averted over 10 years
- £32,947,100 Secondary care costs averted over 10 years
- £3,000,481 prescription costs averted over 10 years
39,287 days off work averted over 10 years
£30,946,000 Discounted NHS cost savings averted over 10 years
7109 Discounted QALY gains over 10 years
Environmental impact of air quality
As well as an impact on people, there is also an environmental impact of poor air quality.
Acid rain
This is caused by sulphur dioxide and nitrogen oxides reacting with water, oxygen and other substances in the atmosphere. This creates sulphuric and nitric acid, which then falls to the ground as acid rain.
The consequences of acid rain are numerous, such as damage to wildlife, ecosystems, health costs to humans and damage to crops, in turn leading to reduced agricultural yields.
Ozone
The ozone layer acts as a natural filter, absorbing most of the sun's burning ultraviolet (UV) rays. Stratospheric ozone depletion leads to an increase in UVB that reaches the earth's surface, where it can disrupt biological processes and damage a number of materials.
UV radiation not only affects humans, but wildlife as well. Excessive UVB inhibits the growth processes of almost all green plants. There is concern that ozone depletion may lead to a loss of plant species and reduce global food supply.
Unlike the ozone layer in the upper atmosphere, ground level ozone, formed from reactions between nitrogen oxides and VOCs, can directly damage plants, harm ecosystems and reduce agricultural yields.
Any change in the balance of plant species can have serious effects. Plants form the basis of the food web, prevent soil erosion and water loss, and are the primary producers of oxygen and primary sink (store) for carbon dioxide.
Climate change
Climate change and its impacts is well documented and within the UK, all 10 of the warmest years have occurred since 2003. 2022 was the UK’s hottest year on record, with an average year-round temperature above 10°C seen for the first time.
Many of the same pollutants that impact our health are also categorised as greenhouse gases and are causing climate change.
Climate change is also worsening air quality, with impacts such as the increase in wildfires creating PM2.5 emissions. During the 2019 wildfires in Australia, hospital emissions due to breathing problems increased by 34% in one state.
Damage to ecosystems
Air quality also has an impact on wildlife, with nitrogen emissions posing a particular problem; nitrogen in air pollution (for example ammonia) acts as a fertiliser, making conditions too rich for many wild plants and fungi to survive.
This is bad for the plants and biodiversity more broadly, as animals, especially pollinating insects, depend on these plants for food, nutrients and shelter.
Additionally, nitrogen in the form of ammonia is directly toxic to wildlife and used commonly in agriculture and in everyday human life, such as in AdBlue for cars.
