Millions of people with health problems and the elderly have been warned that the UK will continue to be plagued by record levels of air pollution.
The warning came yesterday as a storm of dust from the Sahara, mixed with pollution from Europe and the UK, caused air quality to plummet.
The smog-like conditions are not expected to clear for some regions until Friday, according to experts.
While the Province largely escaped the worst of it yesterday, there are indications it will increase today, especially in the east.
High levels of pollution are forecast today for East Anglia, the Midlands, Lincolnshire, eastern parts of Wales, through the Wirral and the north coast of Wales.
It is expected this will move north towards Northern Ireland.
In addition, the Met Office was listing a Yellow Weather Warning for Northern Ireland, with heavy rain due to hit the east of the Province.
The warning is set to stay in place until midnight tonight.
Those with lung and heart conditions across the UK have been told to continue to avoid strenuous activity outdoors while people suffering symptoms of pollution – including sore eyes, coughs and sore throats – should cut down the amount they do outside, health experts said.
Asthmatics have been warned of the need to use their blue reliever inhalers more often as they could be prone to attacks over the next few days.
The advice, from Public Health England (PHE), Asthma UK and the Department for Environment, Food and Rural Affairs (Defra), comes after a warning that parts of England are experiencing the highest level of air pollution ever recorded by Defra.
Defra ranks air pollution from one to 10, with one being the lowest and 10 the highest.
Across most of England, moderate-to-high air pollution levels have been forecast, with level 10 – “very high” – forecast in parts of East Anglia and the East Midlands.
Sotiris Vardoulakis, head of air pollution at PHE’s centre for radiation, chemical and environmental hazards, said most people will not be affected by short-term peaks in air pollution.
However some groups, such as those with existing heart or lung conditions, may experience increased symptoms.
Paul Cosford, director of health protection at PHE, told BBC Radio 4’s Today programme that the air pollution was a “serious issue” but should be kept in perspective.
“It’s a small number of days of very high air pollution levels,” he said.
“The pollution will go down towards the end of the week.”
Dr Helen Dacre, a meteorologist at the University of Reading, said conditions had conspired to create a “perfect storm” for air pollution.
“British car drivers and heavy industry create bad enough smog on their own, but the weather is also importing pollution from the industrialised urban parts of Europe, which is blowing across Britain.
“Saharan dust gets blown over to Britain several times a year – the current episode has been whipped up by a large wind storm in North Africa. This has all combined to create high concentrations of pollutants in the air.”