Air pollution is linked to increased risk of developing an irregular heartbeat and blood clots in the lung, research suggests.
The impact of air pollution on the risk of heart attack and stroke is less clear, say UK experts.
Analysis of data from England and Wales shows air pollution is particularly harmful in the elderly.
Further research is needed on pollution and cardiovascular health, says the British Heart Foundation.
A team at the London School of Hygiene & Tropical Medicine analysed data collected in England and Wales between 2003 and 2009 on links between cardiovascular problems and short-term air pollution.
They found short-term air pollution was linked to arrhythmia (abnormal heart rhythm) and blood clots in the lung.
The strongest link was in the over-75s and in women, lead researcher Dr Ai Milojevic told BBC News.
Who would have thought that breathing air you can’t see through would have negative side effects? More importantly, why is pollution discriminating against the elderly?
Just thinking about this makes my heart race.