1. Smog Atmospheric pollution in urban areas Poor air quality affects 50% of the world’s urban population - 1.6 billion people. In the USA it is estimated that costs related to air pollution are about $40 billion each year.

2. Smog around the world  Italian cities fight smog A blanket of smog across northern Italy forces city authorities to ban cars, as old and young are warned to stay indoors. Italian cities fight smog Italian cities fight smog  Moscow 'suffocated' by smog Asthma sufferers and pregnant women are advised to leave Moscow as smog caused by forest fires blankets the city. Moscow 'suffocated' by smog Moscow 'suffocated' by smog  Minister claims Mexico smog breakthrough Mexico City's Environment Minister Claudia Sheinbaum claims that the city's notorious smog problem is improving. Minister claims Mexico smog breakthrough Minister claims Mexico smog breakthrough  Indonesian fires cast smog cloud Smog caused by forest fires in Kalimantan and Sumatra has caused a health alert and severely reduced visibility across the region. Indonesian fires cast smog cloud Indonesian fires cast smog cloud  Smog crisis in Santiago The authorities in the Chilean capital, Santiago, introduce tough measures to combat dangerously high pollution levels. Smog crisis in Santiago Smog crisis in Santiago  Smog smothers Malaysia A cloud of haze shrouds half of Malaysia, sparking fears of a re-run of the smog chaos in the region three years ago. Smog smothers Malaysia Smog smothers Malaysia

3. Smog kills  Each year several hundred thousand people die due to poor air quality and many more are seriously affected.  In Europe ¾ of cities with populations > 500,000 have poor air quality.  20% of the population in the developed world are at risk from health related problems to air pollution.  The death rate for asthma has increased 46-60% in recent decades and is one of the most common causes of hospital admissions for children. (1 in 7 children in the UK now suffer from asthma).

4. Why is the problem increasing? Increases in population growth in urban areas Industrial development Increases in numbers of vehicles world wide

5. Major Pollutants and their Dangers MajorAtmospheric pollutants of urban areas Photochemical oxidants (ozone) cause vegetation damage, headaches, eye irritation, chest pains Carbon monoxide causes heart problems, headaches, fatigue Sulphur dioxide causes haze, acid rain, respiratory problems Particulates from power stations, vehicle exhausts cause respiratory problems, soiling of buildings and are carcinogens Oxides of nitrogen cause weathering, acid rain, respiratory problems

6. Under what climatic conditions is air pollution most hazardous?  Air pollution varies with the time of year and air pressure conditions.  Concentrations of pollutants may increase 5-6 times in winter because of temperature inversions trapping them over the city.

7.  Temperature inversions are associated with clear skies  Calm conditions typically found under an anticyclone.  Light winds allow the pollutants to remain in the area and not to be dispersed.  Because anticyclonic conditions are stable, poor air quality can persist for many days.  Fog developing under these conditions mixes with the pollutants and a SMOG is formed.

8.  This was a common occurrence in the cities of Western Europe in the nineteenth century brought about by the high incidence of coal burning.  Britain suffered particularly badly many of the smogs being so thick that the term ‘pea-soup’ was applied to them. In 1952, a smog lasted several days and claimed 4000 deaths. This led to the British government taking action to legislate to control coal burning.