Air pollution warning in effect for Mon Valley

MON VALLEY (KDKA) -- The Allegheny County Health Department has issued an air pollution warning for the Mon Valley area. 

The warning started late this morning and continues through tomorrow. 

Health officials warn that individuals with health conditions such as asthma, bronchitis and emphysema should be careful during this time. 

The department also stated that "companies most significantly contributing to particulate pollution ... are required to temporarily reduce particulate emissions."