UK, Indian scientists investigate air-pollution causes

British and Indian scientists are working to understand the sources, causes and effects of pollution after fireworks during Diwali and Guy Fawkes' night sharply reduced visibility in the two countries.
Scientists at the University of Birmingham and their partners in Delhi have co-organised a workshop in Delhi next month to investigate air pollution in the two countries.
The worshop will be attended by Francis Pope and Mukesh Khare of the Indian Institute of Technology. It is sponsored by the British Council and follows work at Birmingham which discovered that there is a sharp reduction in visibility caused by fireworks during Diwali and Guy Fawkes' night.

Birmingham scientists found that visibility was further decreased when the relative humidity was high.
Pope, from the University's School of Geography, Earth and Environmental Sciences, said: "Events such as Diwali celebrations and Guy Fawkes' Night are attended and much enjoyed by many people in India and the UK. Unfortunately, these events can affect short term air quality and lead to significant reductions in visibility.
"We hope that our Delhi workshop will help us to better understand the causes, sources and effects of pollution in India and the UK and how they differ between the two countries.

"If forecasts suggest that planned displays will coincide with conditions likely to exacerbate poor visibility, then organisers and local authorities should be prepared to issue poor visibility warnings in advance. This precautionary measure could help to prevent unnecessary accidents."

Guy Fawkes Night, or Bonfire Night, is an annual event marking the foiling of a plot by Catholic conspirators to blow up Protestant king James I and the Houses of Parliament with 36 barrels of gunpowder on November 5, 1605.
Pope's research used data taken over 13 years between 2000 and 2012 from 34 meteorological stations throughout the UK the scientists noted an average 25 per cent reduction in visibility caused by atmospheric particulate matter from fireworks and bonfires.
If the conditions are unfavourable then the visibility reduction can be much more severe; for example, visibility reductions of 64 per cent were seen in Nottingham.

Fireworks celebrations usually involve both bonfires and ground and air detonating fireworks.
The particulate matter that is scattered after detonation is hygroscopic - its water content is dependent on the local relative humidity.
As the humidity increases so does the water content of the particulate matter, changing the average size and composition of each particle, which leads to the particle being able to scatter light more effectively and hence reduce visibility.
The effects, which were especially pronounced when humidity was high, raise concerns regarding motorist and pedestrian safety.
The visibility reducing effect of the extra particulate matter loading in the atmosphere can last up to two days after the fireworks event.