From the CDC:
“Secondhand Smoke Harms Children and Adults
There is no risk-free level of secondhand smoke exposure; even brief exposure can be harmful to health.1,2,6
Since 1964, approximately 2,500,000 nonsmokers have died from health problems caused by exposure to secondhand smoke.
Health Effects in Children
In children, secondhand smoke causes the following:1,2,3
Ear infections
More frequent and severe asthma attacks
Respiratory symptoms (for example, coughing, sneezing, and shortness of breath)
Respiratory infections (bronchitis and pneumonia)
A greater risk for sudden infant death syndrome (SIDS)
Health Effects in Adults
In adults who have never smoked, secondhand smoke can cause:
Heart disease
For nonsmokers, breathing secondhand smoke has immediate harmful effects on the heart and blood vessels.1,3
It is estimated that secondhand smoke caused nearly 34,000 heart disease deaths each year during 2005–2009 among adult nonsmokers in the United States.1
Lung cancer1,7
Secondhand smoke exposure caused more than 7,300 lung cancer deaths each year during 2005–2009 among adult nonsmokers in the United States.1
Stroke”