WATERLOO - The National Weather Service in Des Moines has issued an air stagnation advisory for northern Iowa, including Waterloo, Waverly, Eldora, Grundy Center and Allison, among other cities.

The advisory will remain in effect until midnight.

The advisory is at the request of the Iowa Department of Natural Resources. Fine particulate levels near EPA health standards were present over the northern half of Iowa this morning. Elevated levels are expected to persist through midnight today.

The DNR recommends that Iowans with respiratory or heart disease, the elderly and children limit prolonged outdoor exertion until air quality conditions improve.

An air stagnation advisory indicates that due to limited movement of an airmass across the advisory area, pollution will increase to dangerous levels. Persons with respiratory illness should follow their physician's advice for dealing with high levels of air pollution.