Property listings will include traffic light-style pollution warnings in the near future, experts have predicted as they said poor air quality can knock up to 15 per cent off house prices.

Pollution has become a top concern among potential buyers, who are snubbing “unhealthy homes” and have started using sophisticated pollution websites to track air quality.

The trend has prompted calls for new rules which force estate agents to publish traffic light style pollution warnings alongside energy efficiency ratings in property adverts.

A toxic air alert was issued for the first time in London over “very high” pollution levels, sparking major public concern over the health impacts of living in congested areas.

Nearly 9,500 people died early in a single year as a result of long-term exposure to air pollution in London, a Kings College London report claimed.

Concerned buyers have started actively researching granular data through websites which let them track air quality at individual postcodes, they said.

Henry Pryor, a professional home buyer and property agent, said:

“Home buyers used to have a blaze attitude to air pollution but now this has completely changed. People are very concerned and they are suddenly discovering that they can look at two homes at different ends of a street, and one will be more polluted than another.

“I get asked about pollution levels so regularly that I now check it as standard before suggesting a property to clients. If a house is in a highly polluted area, such as near a train line, it might go for a 15 per cent less than a similar property in a less polluted zone.”

Read more: The Telegraph