Air pollution from both outdoor and indoor sources is the single largest environmental risk to health globally according to the World Health Organisation (WHO). An estimated 7 million people are killed each year by air pollution. Their new report shows that 92% of the world’s population live in places where air pollution levels exceed World Health Organisation limits. (1)
Most of the major cities in the world routinely exceed WHO air pollution guidelines. This chart looks at just one of the dangerous pollutants, PM2.5 particulates, and compares the average annual levels of this pollutant in 12 major cities, all of which exceed the guideline. (2)
But there are many other dangerous air pollutants as well as PM2.5. In the UK approximately 40,000 people die prematurely each year from respiratory, cardiovascular and other illnesses associated with pollutants such as NO2, particulate matter (PM) and ozone.
Within Europe, some 40 million people living in the 115 largest cities are exposed to air that exceeds what is considered safe.
Because of the severity of this global problem, The World Health Organisation is rolling out ‘BreatheLife’, a global communications campaign to increase public awareness of air pollution as a major health and climate risk. Watch the short video released to launch the campaign. You can also use the website to check out the air quality in some cities in the UK and around the world.
The ‘BreatheLife’ video rightly focuses on children. Unicef revealed recently that 300 million children live in areas with extreme air pollution – six times higher than international guidelines – and that almost 90% of the world’s children live in places where outdoor air pollution exceeds World Health Organization limits. A recent study showed that a quarter of schools in London are in areas with illegal levels of air pollution. Not only does it damage children’s health and kill them, it also harms their cognitive or mental development. (3)
So what is causing this dramatic deterioration in the healthiness of the air we breathe?
The Impact of Human Activity on Air Quality
Air Pollution resulting from human activity is not a new thing. In Europe, during the Middle Ages, the burning of coal resulted in increasing amounts of smoke and sulphur dioxide in towns.
In 1257, Queen Eleanor claimed she was driven out of Nottingham Castle by the terrible smoke and fumes from the coal fires in the city below.
Complaints about air quality in London led to the use of coal being prohibited in London in 1273. And in 1307, Edward 1 issued a Royal Proclamation forbidding lime-burners to use coal in parts of south London. Both measures had little effect. (4)
The Industrial Revolution, starting in the eighteenth century, made matters worse. As industrialisation grew throughout the following centuries, the quality of the air in towns and cities in Britain deteriorated rapidly.
The London Smog of 1952
However, it was the famous London Smog of 1952, which eventually alerted people to the considerable health dangers of air pollution. Smog was nothing new to London but conditions in December 1952 created a poisonous cocktail that had devastating consequences. Over 4,000 people died in one week. Within a month air pollution had killed 12,000 people. There were approximately 150,000 hospitalisations and thousands of undocumented animal deaths.
Watch the short video below about the 1952 London Smog. Despite the gung-ho tone of the narrator and the sexist references to nagging wives, which was typical of the newsreels of the period, it contains some interesting footage.
The 1952 ‘Great London Smog’ is still considered to be the worst air pollution event in European history. Yet the reason why it was so deadly has never been totally clear. Recently, a team of scientists attempted to re-create the fog conditions in a laboratory experiment. Their study revealed the likely cause was pollutants already present in the fog mixed with the nitrogen dioxide and sulphur dioxide from the domestic and industrial burning of fossil fuels to create a lethal sulphuric acid haze. (5)
The government of the time could not ignore the devastation of the ‘Great London Smog’ and in 1956 the first Clean Air Act was introduced. This and later legislation introduced Smoke Control Areas or smokeless zones in an effort to clean up cities. (6)
These measures led to a dramatic reduction of air pollution as:
- the use of solid fuels decreased
- the coal that was used was cleaner with a lower sulphur content
- electric and gas usage increased
- power stations were relocated to rural areas
- taller chimney stacks were built
- there was a continued decline in heavy industry
During the following decades, the air became visibly cleaner and the great smogs and clouds of pollution that had shrouded UK cities for so long, gradually cleared.
More recently, however, we are realising that even though we can’t always see the air pollution in our towns and cities, it is still there. Only now it’s become an invisible killer.
Air Pollution Today
So what is causing this resurgence in deadly air pollution? Today we know far more about the nature of air pollution than we did in 1952. Recent scientific studies show that there’s been a shift from the pollution problems caused by industry to ones associated with transport emissions, in particular, petrol and diesel motor vehicles which emit a wide variety of pollutants. Except for the worst-case situations, the impact on air quality from industrial and domestic pollution has tended to be steady or improving over time. However, traffic pollution problems are worsening worldwide.
Watch the video below where Professor Frank Kelly talks about the changing nature of air pollution today.
Published on 5 Nov 2014
Effects on Human Health of Air Pollution
A variety of air pollutants have known or suspected harmful effects on human health and the environment. In most areas of Europe, pollutants are mainly the products of combustion from heating, power generation and from motor vehicle traffic. Pollutants from these sources are not only a problem in the immediate area in which they arise but can travel long distances.
The tables below shows the types of health effects of the most common pollutants (7)
|Particulate Matter (PM10 & PM2.5)||Main UK sources||Potential Health Effects|
|PMs are ‘tiny particles’ present in the air in the form of dust, smoke and vapour.
PM particles vary in size. Most secondary particles are very small and are identified as fine particles. They are equivalent to 2.5 – 10 millionths of a meter – at least 10 times smaller than the width of a human hair.
|Primary particles are released directly into the atmosphere as a product of combustion, road transport and some natural activities such as Saharan dust and pollination.
In the UK, the biggest source is fuel combustion and transport, particularly diesel fumes.
Secondary particles are produced via chemical reactions with other pollutants such as nitrogen oxides, sulphur dioxide and ammonia in the atmosphere.
|Small particulate pollution has health impacts even at very low concentrations.
Fine particles can be carried deep into the lungs where they can cause inflammation and a worsening of heart and lung diseases
Both short-term and long-term exposure are associated with respiratory and cardiovascular illness and mortality.
PM2.5 is associated with a higher risk of mortality from lung cancer and other diseases, especially as a result of long-term exposure.
|Nitrogen Dioxide (NO2) & Nitric Oxide (NO)||Main UK sources||Potential Health Effects|
|All combustion processes in air produce oxides of nitrogen. Nitrogen dioxide is a harmful gas produced by burning fossil fuels.||Road transport is the main source of Nitrogen Dioxide and Nitric Oxide, in particular, diesel fumes.
Other sources include gas boilers used for heating and burning coal and gas in power stations to produce electricity.
However, most of the NO2 in urban areas is produced from vehicle exhausts (the major source in the UK)
London is the worst city for NO2 pollution
|The UK has the 2nd highest number of deaths due to NO2 pollution in Europe. High levels of these gases cause respiratory diseases and lung infections.
People who already have breathing problems are more susceptible and long-term exposure increases symptoms of bronchitis.
Children living near roads with heavy traffic have twice the risk of respiratory problems.
It has an adverse effect on plants and biodiversity.
Outdoor Air Pollution Deaths
The World Health Organisation has done a summary of the health risks of air pollution. Included in their assessment is a breakdown of deaths caused by outdoor air pollution. (8)
|Outdoor air pollution-caused deaths by disease|
|Coronary Heart Disease|
|Chronic Obstructive Pulmonary Disease|
|Acute Respiratory Infections in Children|
Estimates are based on WHO mortality data
Of course, air outside also gets indoors and that includes polluted air. In addition, there are other sources of air pollution from within buildings, and this includes our homes, schools and workplaces. So the air indoors can potentially be more dangerous than the air outside.
View this short video ‘Every breath we take’ where Professor Stephen Holgate from the University of Southampton, Faculty of Medicine talks about the problem of indoor air pollution.
As Professor Holgate suggests a growing body of scientific evidence indicates that the air within homes and other buildings can be more seriously polluted than the outdoor air in even the largest and most industrialised cities. In addition, it is estimated that people spend approximately 90 percent of their time indoors. Therefore for many of us, the risks to health may be greater from exposure to indoor air pollution than outdoor pollution.
So what are the additional pollutants found inside buildings?
The main sources of indoor air pollution are outlined below:
Gas cookers, wood stoves, solid fuel open fires and gas or paraffin heaters are potential sources of indoor air pollution. If an appliance is faulty, incomplete combustion may result in the release of carbon monoxide, a highly poisonous gas. Nitrogen dioxide is produced by gas cookers. Proper fitting and regular checking of appliances is vital. Ventilation is also key to reducing levels of indoor air pollutants. Poor ventilation generally can mean that harmful particles and gases build up in an indoor environment.
Houseplants are thought to have beneficial effects on indoor air. Research by NASA shows that plants and flowers can absorb harmful and toxic gases in our homes and workplaces. (See appendix for list of plants)
Toxic Chemical and Fibres
Toxic chemical sources include solvents which occur in paints, varnishes and glues and formaldehydes and preservatives which are used in wood products. Volatile organic compounds (VOCs) can be released during painting or paint stripping in enclosed spaces or laying of loft insulation. Newly built homes can have high levels of indoor air pollution from these sources.
Loft insulating fibres such as glass fibres may also be harmful to human health. Asbestos used to be commonly used for insulation but is now known to cause lung tissue scarring and cancer.
Other sources of toxic chemicals include cleaning products, fly sprays, air fresheners and deodorants which can also be harmful to health. As a general rule, spray products are more toxic than solid or liquid products.
Pollutants from cigarette smoking include carbon monoxide, nicotine, tar, formaldehyde, ammonia and nitrogen oxides. There are serious health effects relating to the breathing of air polluted by cigarette smoke, including eye and throat irritations, respiratory problems such as bronchitis and pneumonia, asthma, low birth weight in babies, heart attacks and lung cancer.
Dust mites are microscopic spider-like creatures which live in beds, carpets and other soft furnishings. They are a common source of indoor air pollution and can trigger asthma attacks, inflammation of the lining of the nose and eczema in sensitive people. A dust mite problem can be alleviated by ventilation, ensuring that carpets are kept clean and dry and keeping beds well aired. Regular dusting and vacuuming of soft furnishings will also reduce the incidence of dust mite.
Moulds are a type of fungus. Moulds spread by releasing millions of tiny spores into the air. They need moisture to grow and are usually found in damp, poorly ventilated areas of buildings such as kitchens or bathrooms. You cannot see the spores but you may be able to see moulds, grey, green or black in colour, growing on damp surfaces. Mould spores reduce the quality of indoor air and are associated with health problems such as asthma. Indoor air pollution related to damp and mould increases the risk of respiratory disease in children and adults by 50%.
Mould spores can be reduced by improving ventilation and by limiting sources of moisture and condensation.
Indoor air pollution in the workplace which is hazardous or toxic is controlled by legislation called The Control of Substances Hazardous to Health Regulations (2002). In the indoor home environment, the homeowner is responsible for controlling air pollution.
The main sources of nitrogen dioxide and carbon monoxide in the indoor environment are gas cookers and poorly maintained heating appliances. Formaldehyde sources include insulation materials, particleboard and chipboard, water-based paints, cigarette smoke and vehicle exhaust. Sources of volatile organic compounds include building materials, cleaning products, solvents, glues, furniture and tobacco smoke.
These pollutants have wide-ranging effects on human health depending on factors such as the concentration of the pollutant, the amount of ventilation, or the size of the enclosed space. The table below gives a breakdown of deaths caused by indoor pollution.
|Indoor air pollution-caused deaths by disease|
|Coronary Heart Disease|
|Chronic Obstructive Pulmonary Disease|
|Acute Respiratory Infections in Children|
Estimates are based on WHO mortality data (9)
Air pollution is a major environmental risk to health. The World Health Organisation (WHO) has declared it a public health emergency.
There are many factors that affect air quality and many sources of pollution, both indoor and outdoor which affect health. Air quality can be difficult to monitor as pollution levels vary over time. It can change throughout the day and differ during the seasons depending on weather conditions and emission sources.
Some pollutants are more heavily concentrated in different areas. For example, areas where solid fuel is used a lot for domestic heating are likely to have higher emissions of sulphur dioxide pollution. Transport can generate high levels of nitrogen dioxide, carbon monoxide and hydrocarbons in cities and towns. Particulate pollution may be high as a result of vehicle pollution, fuel burning, building work, industrial emissions, soil and road dust and quarrying.
Pollution emissions in other countries can also be transported across international borders to create high levels of pollutants such as ozone.
Dr Ben Barratt of the Environmental Research Group at King’s College London argues that we should be thinking about the quality of our air all the time. Watch the short video below.
Published on 27 Oct 2015
It is estimated that outdoor air pollution is linked to around 40,000 deaths in the UK each year, more deaths than obesity and alcohol. The figure is even higher if we add deaths related to exposure to indoor pollutants. As outlined in the sections above, it has been linked to cancer, asthma, stroke and heart disease, diabetes, obesity, dementia and Alzheimer’s disease. The health problems caused by exposure to air pollution not only have a high cost for individuals and families who are affected by them, they also incur costs to our health service and economy. According to the Royal College of Physicians, in the UK, these costs add up to more than £20 billion every year.(10)
By reducing air pollution levels, countries can reduce the burden of premature death and disease. The lower the levels of air pollution, the better the cardiovascular, respiratory and cognitive health of the population will be. The following Module Law and Government Policy will explore what is being done to tackle this public health emergency.
- Enviropedia: http://www.air-quality.org.uk/02.php
- (adapted from Department for Environment Food and Rural Affairs (Defra) pdf ‘What are the causes of air Pollution’)
- ‘Every breath we take: the lifelong implication of air pollution’ – Royal College of Physicians https://www.rcplondon.ac.uk/projects/outputs/every-breath-we-take-lifelong-impact-air-pollution
‘You can taste it in the air’: your stories of life in polluted cities. Readers from around the world share their experiences of living in cities affected by air pollution https://www.theguardian.com/cities/2017/feb/16/taste-air-pollution-smog-your-stories-life-polluted-cities
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