Air pollution is “the new tobacco…”

Air pollution causes 1 in 9 deaths worldwide

Air pollution is “the new tobacco…” said Dr Tedros Adhanom Ghebreyesus, WHO’s Director-General

The World Health Organisation states that air pollution kills an estimated 7 million people worldwide every year. WHO data shows that 9 out of 10 people breathe air containing high levels of pollutants. Air pollution is an invisible killer that lurks all around us, slipping unnoticed past our body’s defenses, causing deaths from heart attack, strokes, lung disease and cancer.

The first WHO Global Conference on Air Pollution and Health took place in Geneva from 30th October to 1st November 2018. It was the first-ever global event to focus on both air pollution and health and concluded with a proposal to reduce the number of deaths from air pollution by two thirds by 2030.

Ambient (outdoor) air pollution

This is a major threat to health and climate, which according to WHO, accounts for an estimated 4.2 million deaths per year.

“Around 91% of the world’s population lives in places where air quality levels exceed WHO limits. While ambient air pollution affects developed and developing countries alike, low- and middle-income countries experience the highest burden, with the greatest toll in the WHO Western Pacific and South-East Asia regions.” – from WHO

You can also download the report “Evolution of WHO air quality guidelines: past, present and future (2017)”  This summarises key WHO publications in the field of air quality and health since the 1950s, which led to the development of the series of WHO air quality guidelines.

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An Air Quality Index

An air quality index (AQI) is a number used by government agencies to tell the public how polluted their air currently is or how polluted it is forecast to become. As the AQI increases, an increasingly large percentage of the population is likely to experience increasingly severe adverse health effects. Different countries have their own air quality indices, corresponding to different national air quality standards.

United Kingdom

The air quality index in the UK is the Daily Air Quality Index recommended by the Committee on Medical Effects of Air Pollutants. This index has ten points, which are further grouped into 4 bands: low, moderate, high and very high. Each of the bands comes with advice for at-risk groups and the general population.

Air pollution banding Value Health messages for At-risk individuals Health messages for General population
Low 1–3 Enjoy your usual outdoor activities. Enjoy your usual outdoor activities.
Moderate 4–6 Adults and children with lung problems, and adults with heart problems, who experience symptoms, should consider reducing strenuous physical activity, particularly outdoors. Enjoy your usual outdoor activities.
High 7–9 Adults and children with lung problems, and adults with heart problems, should reduce strenuous physical exertion, particularly outdoors, and particularly if they experience symptoms. People with asthma may find they need to use their reliever inhaler more often. Older people should also reduce physical exertion. Anyone experiencing discomfort such as sore eyes, cough or sore throat should consider reducing activity, particularly outdoors.
Very High 10 Adults and children with lung problems, adults with heart problems, and older people, should avoid strenuous physical activity. People with asthma may find they need to use their reliever inhaler more often. Reduce physical exertion, particularly outdoors, especially if you experience symptoms such as cough or sore throat.

United States

The United States Environmental Protection Agency (EPA) Air Quality Index is divided into six categories indicating increasing levels of health concern. An AQI value over 300 represents hazardous air quality and below 50 the air quality is good.

Air Quality Index (AQI) Values Levels of Health Concern Colors
0 to 50 Good Green
51 to 100 Moderate Yellow
101 to 150 Unhealthy for Sensitive Groups Orange
151 to 200 Unhealthy Red
201 to 300 Very Unhealthy Purple
301 to 500 Hazardous Maroon

Air Quality Index Color Code Guide

The United States Department of Agriculture Forest Service has produced a chart showing the weather conditions associated with the different levels of air quality, plus the possible health effects and their recommended actions. This chart shows the common weather conditions associated with the respective air quality levels.

World’s Air Pollution: Real-time Air Quality Index

A website allowing government agencies anywhere in the world to submit their real-time air monitoring data for display using a common definition of the air quality index is available at The World Air Quality Index project is a non-profit project started in 2007. Its mission is to promote Air Pollution awareness for citizens and provide a unified and world-wide Air Quality information.

photo of cityscape covered in fog
Photo by AJ Nakasone on

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