Joanne Ward was 30 when she had her second son eight years ago. It was a straightforward birth and she was happy to go home soon thereafter. Four days later, she was back in hospital after a heart attack so severe that today she has a pacemaker for a heart that still does not pump properly.
She has learnt to cope with her coronary condition but one problem she did not anticipate was air pollution. “It’s bizarre,” she says, explaining that she never had so much as hay fever before her heart attack but now has days when she goes outside and “it’s like you have a thousand knives going into your chest”, especially on a busy city street.
Ms Ward’s concerns are not isolated. Researchers know smog raises the risk of heart problems but a study this week suggests it can also worsen the condition of people with existing heart disease.