High air pollution levels were recorded in London and the south of England yesterday (1 December), with alerts displayed across the capital.
Cold and stagnant weather resulted in poor dispersal of traffic pollutants, particularly fine particulate matter (PM2.5) and gas nitrogen dioxide (NO2), which is largely created by diesel cars, lorries and buses.
In London, air quality alerts were issued at a number of bus stops, tube stations and at the roadside.
The Mayor of London, Sadiq Khan, announced the introduction of the air pollution alerts in August, so that people can take action to protect their health (see AirQualityNews.com story).
The Department for Environment, Food and Rural Affairs (Defra) advised anyone experiencing discomfort such as sore eyes, a cough or sore throat to avoid strenuous physical exercise, particularly outdoors. People with asthma were warned they may need to use their reliever inhaler more often than usual.
Commenting on the pollution episode, Sadiq Khan said: â€œLondoners need to know when the city is suffering from high-pollution levels so they can take any necessary appropriate measures to protect themselves from poor air quality.â€
He added: â€œThis is particularly crucial for Londoners who are vulnerable, such as asthma sufferers.â€
According to the London Air Quality Network, which is managed by the Environmental Research Group (ERG) at King’s College London, winter â€˜smogâ€™ is formed when pollutants are trapped at ground level because of a temperature inversion. This usually lasts until there is a change in the weather.
Particles smaller than 10 micrometers (PM10) and smaller than 2.5 micrometres (PM2.5) can settle in the airways and lungs and cause health problems.
Dr Ben Williams, research associate at the UWEâ€™s Bristolâ€™s Air Quality Management Resource Centre, said that in terms of pollution build-up â€œa lot of it was down to cold stagnant air, with people sitting in traffic and pumping out pollutants which canâ€™t get away.â€
He added that Bristol has a particular problem around vehicle emissions: â€œThereâ€™s a lot of congestion in and around Bristol, which is clearly not good for air quality.â€
As for alerting the public, Dr Williams said: â€œThe only way that [high air pollution] is really being conveyed in a meaningful way is through the media. It doesnâ€™t feel like a really well-known issue, it should be much higher up the agenda.â€
Dr Williams added that the alerts in London â€œare a positive way of communicating a very difficult message and I think Bristol would benefit from similar approaches.â€