This worrying picture shows the toxic smog cloud hanging over Portsmouth.
The pollution that blew across to the UK from the continent - caught clearly on camera from Portsdown Hill by photographer Shaun Roster - has led to health concerns and renewed calls for EU limits to combat air pollution.
Government officials issued a health alert, warning those with existing heart or lung conditions, young children and the elderly to refrain from strenuous exercise, especially outside.
High levels of pollution which were recorded in Paris on Wednesday, combined with home-grown smog, resulted in moderate to high levels across parts of England and Wales.
Portsmouth Euro MP, Catherine Bearder, has been a long-term campaigner on air pollution levels and is the EU Parliament’s Liberal group lead negotiator on air quality law.
Mrs Bearder said: ‘Deadly smog in Paris has led to dangerous levels of pollution in Portsmouth.
‘This is a reminder that air pollution doesn’t respect national borders, and neither should our efforts to tackle it.
‘We urgently need to put in place strict limits across Europe that will force governments to take action and improve air quality. The longer we wait, the longer people will continue to suffer from the health impacts of air pollution.’
Hampshire experienced moderate to high pollution levels which were expected to return to normal today as changes in the weather help to disperse the smog.
Dr Andrew Whittamore is a Portsmouth GP, primary care lead for Wessex respiratory team and clinical advisor to Asthma UK.
‘The smog issue is a worry generally but people with lung conditions are going to struggle more,’ he said.
‘The people who struggle most are people who breathe faster than others, so children and athletes are particularly at risk.
‘People at risk should stay inside and keep the windows closed and make sure that they know what to do when their asthma is uncontrolled.’
Dr Whittamore also supports efforts to limit pollution in Europe.
A 12mph (20kph) speed limit on Paris motorways was imposed by police on Wednesday after a rise in air pollution.
The resulting smog cloud which blew across the Channel also affected other regions in England and Wales.