High pressure and very few winds is causing pollution from Europe to hang over Wirral today.
The Met Office has said the area is expected to expereince medium or high levels of pollution due to smog being blown in from Europe.
A Met Office spokeswoman said: “Winds bringing in pollution from the continent, combined with locally generated pollution and still weather conditions has led to some high pollution measurements across the UK.
She added: “Levels are expected to return to low by Friday.”
A Defra spokesman has said: “The elderly, young and those with heart and lung conditions should avoid strenuous activity, especially outdoors, adding that those with asthma may also experience increased breathing problems.”
Kay Boycott, chief executive of Asthma UK, said: “Two thirds of people with asthma find that air pollution makes their asthma worse, putting them at an increased risk of a potentially fatal asthma attack.
“When air pollution is high it’s vital people with respiratory conditions including asthma check air pollution forecasts, carry their reliever inhaler with them at all times, and ensure that they are taking their preventer inhaler every day because this will help build resilience to asthma triggers like air pollution.
Each level has associated health information and advice for the general public as well as those that may be more sensitive to air pollution, so please check the Defra website here for more information.
Air quality will improve as the day progresses.