Air pollution levels could reach a high level in Reading , Wokingham and Bracknell on Friday.
Stronger winds are set to sweep in by the end of week which means it’s bad news for hayfever sufferers.
And those who suffer from lung or heart problems are being urged to reduce any strenuous physical activity, and people with asthma may need to use their inhaler more often.
Anyone experiencing discomfort such as sore eyes, a cough or sore throat should consider reducing activity, particularly outdoors.
Air levels should return to normal on Saturday.