Air pollution alerts straight to you

When you sign up to receive pollution alerts from airTEXT, you select a zone that you'd like to receive the alerts for. Twice every day at about 7am and 7pm, computers at CERC's forecasting office make a prediction of the air pollution on every street in London for the rest of today or all of tomorrow.

When air pollution levels are predicted to reach MODERATE or higher levels over more than one tenth of your zone, we will send you an SMS message, a voice mail or an email, to warn you that pollution may be elevated. You can then take the advice offered in the alert, check the Health Advice section on the airTEXT website, and read this leaflet (PDF file).

The forecasts are performed using CERC's airTEXT air pollution forecasting and alert system. It works like this. The system combines information from weather forecasts, European wide pollution forecasts and very detailed local pollution source data in a complex mathematical model based on an advanced quasi-gaussian solution to the advection diffusion equations modified for convection.

Put simply, this means that the model doesn't account for the detailed effects of individual buildings or chaotic flows from strong winds, but it does include such effects as pollution building up along major roads with tall buildings - "street canyons" - and the diluting effect of rising warm air.

In total, the airTEXT system for London models the effects of about 30,000 pollution sources around the city.