Days when pollutant levels across the UK were in the top half of the annual range saw an extra 124 cardiac arrests, according to new research* from King's College London.
Researchers say sudden spikes in air pollution trigger hundreds more heart attacks, strokes and acute asthma attacks on those days. They said the effects were most acute in London where high-pollution days caused an extra 87 cardiac arrests on average, an extra 144 strokes, and 74 children and 33 adults ending up in hospital with asthma-related issues.
Birmingham saw 12 more out-of-hospital cardiac arrests, 27 additional admissions for stroke and 26 more for asthma.
Bristol, Liverpool, Manchester, Nottingham, Oxford and Southampton saw between two and six more out-of-hospital heart attacks and up to 14 extra hospital admissions for both stroke and asthma on high-pollution days. Only in Derby was there no apparent increase.
Reacting to the figures NHS England chief executive Simon Stevens said: “It's clear that the climate emergency is in fact also a health emergency.
"Since these avoidable deaths are happening now - not in 2025 or 2050 - together we need to act now."
The figures were published ahead of Wednesday's International Clean Air Summit hosted by Mayor of London Sadiq Khan and the UK100 network of local government leaders.
The figures were based on ambulance call data and do not count heart attacks suffered by patients already in hospital. Researchers point to significant short-term health risks caused by air pollution, on top of contributing to almost 500,000 premature deaths in Europe every year.
On days with high pollution levels, across the nine cities in total, there was an average of 231 additional hospital admissions for stroke, with an extra 193 children and adults taken to hospital for asthma treatment.
Dr Heather Walton, of King's College London's Environmental Research Group, said air pollution reduction policies concentrated in the main on effects connected to life expectancy.
"However, health studies show clear links with a much wider range of health effects," she added.
Among the long-term risks associated with high pollution levels are stunted lung growth and low birth weight.
The King's College research also suggests cutting air pollution by a fifth would decrease incidents of lung cancer by between 5% and 7% across the nine cities surveyed.
UK100 director Polly Billington said: "Local government needs additional powers and resources to address this public health crisis." She called for the government’s environment bill, which was set out in the Queen’s Speech last week, to include World Health Organisation air pollution standards, as they are seen as the gold standard, with a legally binding timetable to meet them.
The Department for Environment, Food and Rural Affairs said it was "taking urgent action to improve air quality and tackle pollution" and that new legislation will "increase local powers to address key sources of air pollution".
"We are already working hard to reduce transport emissions and are investing £3.5 billion to clean up our air."
*Personalising the Health Impacts of Air Pollution: Interim Statistics Summary for a Selection of Statements. A report prepared by the Environmental Research Group, King’s College London, October 2019.