London air pollution warning works by issuing a warning across the city when air pollution levels reach a certain threshold. However, the specific details of how this warning system operates are not provided in the given evidence. The evidence only mentions that a toxic air pollution warning is issued across foggy London, but it does not explain the criteria for issuing this warning or the procedures in place to alert the public.
The warning is mentioned in the context of a news article, suggesting that the warning is issued by a relevant authority, such as the London government or a local health agency. However, the evidence does not provide any further information about the warning system, including who is responsible for issuing the warnings, how they are communicated to the public, or what actions are taken in response to the warning.
The lack of detail in the evidence makes it difficult to provide a comprehensive explanation of how the London air pollution warning system works.