Seeing through the fog: Air pollution facts

Key facts and figures on what’s in our air, where it comes from, and why we should worry.

Fight For Fair Air 10th April, 2019

Lorna Stephenson

Key facts and figures on what’s in our air, where it comes from, and why we should worry.

There’s a growing awareness that air pollution damages our health and that as a city we need to take action. But what’s the science behind this? What are the effects on our health? How bad is the problem in Bristol and which areas are worse affected? Get clued up on air pollution.

What are the key pollutants?

What is it?

A gas

Where does it come from?

Road vehicles, and also cooking, heating or power generation

Where does Bristol’s NO2 come from?

Over 80% comes from local traffic sources, over 96% of vehicle NO2 emissions come from diesel vehicles

To fix this, we need less traffic on the roads, but…

• The numbers of cars and vans on Bristol’s roads have tripled in the last 40 years

• Bristol is one of the most dangerous cities to cycle in, with nearly twice the average number of accidents recorded in 2017

• A 2017 study ranked Bristol as the worst city to travel within out of 33 cities

• Congestion can mean buses on certain routes have an average speed of just 6mph

• Only 1 in 11 people commuting in the West of England travel by bus

• Meanwhile, 2 in 3 commutes are by car, and of those, 2 in 5 commutes are less than 2km

What is it?

Small particles – ‘particulate matter’ – in the air, containing a variety of components

The numbers in PM10 and PM2.5 refer to the size of the particulate matter in micrometers. PM2.5, the smallest, is more damaging to human health as it can pass into the body, through the lungs to the bloodstream

Where does it come from?

Road traffic emissions, particularly from diesel vehicles. It is also emitted from industrial combustion plants and public power generation and commercial and residential fuel burning, such as the use of wood burning stoves

• New evidence shows domestic fuel burning, for example from woodburners, contributes 38% of PM2.5 emissions nationally

• Using a woodburning stove, even the most modern and ‘clean’, creates the same PM emissions per hour as 18 diesel cares or 6 lorries.

• There is no safe level of exposure to PM

What are the health impacts?

Research is frequently finding new evidence of air pollution’s impact on our health, such as recent reports on how air pollution may increase the risk of miscarriage or depression. Here are a few of the most common impacts.

Lung Function:
Children – Can stunt lung function growth
Adults – Can make lung function decline faster / Exacerbates respiratory conditions like COPD and bronchitis

Eyes, nose and throat:
Irritation and breathing problems

Neurodevelopment and cognition:
Evidence suggests links between exposure to air pollution and small cognitive deficits in childhood, and accelerated cognitive decline in adulthood

Asthma:
Air pollution can make asthma symptoms worse and can cause onset asthma in children and adults

Cardiovascular (heart):
Exacerbates heart disease, heart attacks, heart failure and strokes

Cancer:
Strong evidence shows that outdoor air pollution causes cancer

Diabetes:
New evidence suggests there is a link between air pollution and type-2 diabetes

Pregnancy:
Low birth weights

Who is most affected?

Percentage of deaths attributable to air pollution differ by ward. Air pollution impacts most on vulnerable groups – children and older people, and those with pre-existing conditions. Air quality is often worse in deprived and central areas – where rates of car ownership are low.

Air pollution impacts most on vulnerable groups – children and older people, and those with pre-existing conditions. Air quality is often worse in deprived and central areas – where rates of car ownership are low.

How does Bristol compare?

In Bristol, early death rates from respiratory disease are significantly higher than the national average. But it has the second lowest rate compared to the eight other ‘core cities’.

How bad is Bristol’s problem?

Thousands of people and dozens of schools reside in Bristol’s Air Quality Management Area, which is exposed to dangerous, and illegal, levels of NO2

Total impact

Sources: Environmental Protection UK, Bristol City Council 2018 Annual Air Quality Status Report, Royal College of Physicians,
2016. Evidence Review, ClairCity, Clean Air for Bristol, Health Impact of Air pollution in Bristol, Bristol City Council,
Travelwest Draft Joint Local Transport Plan 4, BCC Joint Strategic Needs Assessment 2018

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