According to the new map - produced by the non-profit group the Central Office of Public Interest (Copi) and Imperial College London – more than a third of Portsmouth homes endure the highest pollution levels.
The city’s pollution levels match the highest rates recorded outside of Slough and London.
Nationally, more than 97 per cent of addresses exceed WHO limits for at least one of three key pollutants, while 70 per cent of addresses breach limits for all three.
The MP said: ‘Air pollution is an invisible killer but Lib Dems running the council and Tories in Government have shown shocking complacency as the climate crisis deepens.
‘Our densely populated city is now exposed to dangerous levels of dirty air because those in power haven’t done enough, as this independent report reveals.
‘It was Labour that called the climate emergency in our city back in 2019. It’s well beyond time that further action is taken to tackle dirty air in Portsmouth. I will continue to campaign vocally to clean up our air, in our city and across the country. It’s what our communities deserve.’
Mr Morgan has repeatedly called for amendments to the Environment Bill that would have set air quality targets in line with WHO recommendations.