In 1986, the National Dry Deposition Network (NDDN) was established to develop long term estimates of dry, acidic deposition nationwide. NDDN became part of the Clean Air Status and Trends Network (CASTNet) in 1990. Glacier National Park's dry deposition station is composed of sensors that continuously measure ozone and meteorological variables. Particulate sulfate, particulate nitrate, particulate ammonium, sulfur dioxide, and nitric acid are sampled weekly and the data are sent to Environmental Science and Engineering in Florida for analysis.

Ground level ozone is the primary ingredient in smog. This colorless gas, created when nitrogen oxides mix with hydrocarbons in the presence of sunlight, is a respiratory irritant to humans and a threat to vegetation.

Potential health effects of high concentration ozone include irritation, congestion, and swelling of the lung. Repeated exposure can cause permanent structural damage to the lungs and impairment to the body's immune system.

Some plants are affected by ozone. High ozone concentrations cause damage to leaves of plants and injury to hardwood and coniferous trees. It may also result in diminishing agricultural crop yields.

Ozone gas is released into the air through gasoline vapors, chemical solvents, fossil fuel combustion, and products such as glues, paints, and adhesives. Once these vapors are in the air, they react with sunlight to form ozone.

In Glacier National Park, ozone monitors collect continuous data, which are analyzed and stored electronically. Currently, the ozone level in Glacier National Park is significantly lower than the National Park Service average and the ozone trend has remained fairly constant since monitoring began.

The Glacier dry deposition program utilizes a RM Young Meteorological System which collects and records wind speeds, wind direction, temperature, relative humidity or dew point, solar radiation, and precipitation.

Regrowth on Apgar Mountain in the area burned by the 2003 Robert Fire. (photo taken in 2005)