As the images from Beijing continue to show smog researchers have new data about the effects of pollution on the heart.
Experts from the American College of Cardiology reviewed the latest research on air pollution, and found evidence that exposure to ultrafine particles can damage heart and blood vessels.
They say when pollutants are inhaled a series of negative reactions occur including some that activate molecules that can hurt the heart.
Other studies show on high pollution days there's a spike in hospital admissions for heart attack and chest pain.
The elderly and patients already diagnosed with heart disease or diabetes may be especially vulnerable.

And in other medical news…
A new study reports relapse rates for breast cancer are lower than most women think they are.
Researchers at MD Anderson Cancer Center studied nearly three thousand women diagnosed with breast cancer from stages one through three. They found nearly 90 percent of women remained relapse-free ten years after their diagnosis, 80 percent had not had a recurrence fifteen years after they learned they had the disease.
The risk for relapse increased with the stage they were diagnosed at. Women with stage three cancer had a higher risk than those with stage one.
The study also found women with ER positive breast cancer had a greater risk for relapse.