A new study has found that more than half of nonsmokers in Brooklyn have dangerous residue from secondhand smoke in their bloodstream.

The NYC Department of Health study found that high doses of cotinine were found in the bloodstream of nonsmokers. Officials say the residue is not itself harmful, but puts some at a greater risk for heart disease and cancer.

Some smokers in Brooklyn shrug off the study, saying they're not convinced cigarettes pose a greater risk than other types of air pollution.