Air pollution encompasses much more than just smog and smoke. When you think about air pollution, you may first consider smoke and smog and the chemicals they contain. 

However, there is also another danger lurking.

Particulate matter (PM) is the sum of all solid and liquid particles suspended in air, many of which are hazardous.

Oftentimes PM causes respiratory problems, such as asthma, bronchitis, and lung infections, but the smallest particles are especially dangerous and have been correlated to diseases other than respiratory conditions. Some are so small that they can enter your bloodstream. 

Stewart Lonky, MD, a toxin expert, joins Andrea and Lisa to explain what PM is, why it's dangerous, and ways you can limit your exposure.