The resulting smoke exposure causes an estimated two million premature deaths annually, with women and young children the most affected.

The Surgeon General reported there was no safe level of smoke exposure at all.

Second-hand smoke exposure is associated with hearing loss in non-smoking adults.

For the study, researchers monitored secondhand smoke exposure over a year for 220 children, slightly more than half of them black, who lived with smokers.

Before the surgery, the patients' families were given general health surveys, which included questions about smoke exposure.

Firefighters are at the greatest risk for acute and chronic health effects resulting from wildfire smoke exposure.

Here are a few statistics on the effects of secondhand smoke exposure:

About 3,000 deaths from lung disease in nonsmokers each year are caused by secondhand smoke exposure.

The researchers said this was probably because most efforts to curtail smoke exposure had occurred in workplaces and public spaces, not the home.

Al-Delaimy was looking for a way to evaluate secondhand smoke exposure.