The government has issued warnings that many areas in the South East will experience high levels of pollution at the beginning of this week.
The high levels are thought to be caused by foggy conditions and low levels of wind.
People with respiratory conditions such as asthma and heart problems should avoid strenuous activity, all other people should look to reducing strenuous activity outside.
Last year Southampton, Oxford and Eastbourne were among the UK’s most polluted cities.
The UK government has been consistently in breach of European limits and last year the High Court ruled that the government had to present a new plan to tackle it and comply with European levels.
Catherine Bearder, long-term campaigner on air pollution and lead Liberal negotiator on the EU National Emissions Ceiling legislation said:
“Air pollution causes 29,000 deaths every year – when will this government wake up and realise that?
“EU legislation is there to protect people but the government’s refusal to comply means the second we get some bad weather we experience dangerously high levels of pollution.
“With public health clearly not figuring on this government’s agenda I am becoming increasingly concerned about their plans for Brexit.”