Those with lung and heart diseases are being urged to be careful due to high levels of air pollution today.
The high level smog is down to a dust storm from the Sahara being blown over Europe combined with normal pollution levels.
People who suffer from lung conditions such as asthma are being told to take their inhalers more regularly if needed.
On Monday readers were confused as to why their cars were covered in dirt but it was later revealed it was down to the dust being blown over from the Sahara.
Pollution levels are as high as eight or nine today in Croydon but with showers expected tomorrow, the quality of air is set to improve.
Professor Frank Kelly of King's College London said tiny particles of pollution could cause problems for asthma sufferers – and contribute to longer-term problems for others.