The Clean Air Act, which was originally passed in 1970, and most recently updated in 1990, authorizes the Environmental Protection Agency (EPA) to set National Ambient Air Quality Standards (NAAQS) for pollutants considered harmful to public health and the environment. The standards currently cover six principle pollutants: carbon monoxide; airborne particulates; airborne lead; sulfur dioxide; ozone and nitrogen dioxide. Data for these pollutants have been collected in Anchorage since 1980.

Currently, Anchorage and the surrounding areas are considered well within the ambient air quality standards for sulfur dioxide, ground level ozone, and nitrogen dioxide. In addition, airborne lead levels in Anchorage dropped quickly once lead was removed from gasoline, with Anchorage falling well below the NAAQS by 1987. For each of these standards, EPA considers Anchorage to having reached “attainment” by having met their standards for all of these pollutants.

The two remaining pollutants that still bear some watching are particulate matter and carbon monoxide. Airborne particulates are composed of dust, ash, soot, and smoke. In addition, particles stirred up during construction activities, while driving on paved and unpaved roads, and from natural sources such as volcanoes and wind blown silt are also defined as particulates .

According to studies done locally, paved and unpaved roads account for over 90% of the particulates in Anchorage and Eagle River. Anchorage is considered in compliance for PM10. Due to violations caused by unpaved roads in the mid-1990’s. Roads were paved to eliminate the major sources of particulates, with Eagle River staying in compliance since these steps were taken. Locally, the only recent violations have occurred due to naturally occurring events such as the eruption of Mt Redoubt in 1989 and Mt. Spurr in 1992, as well as a storm in 2003 with gale force winds.

Particulates that have an aerodynamic diameter of less than 10 micons, called PM10, are of concern because they can be inhaled into the thoracic or lower regions of the respiratory tract where they can do harm. This is often an issue for those who suffer from asthma or upper respiratory illness. Recent studies show that Particulates at 2.5 microns or smaller may cause be even more severe effects then the larger particles, with additional regulatory action being considered by EPA.

Carbon monoxide is a colorless and odorless gas that is produced by incomplete burning of carbon in fuels. Ambient levels of carbon monoxide are mostly of concern to those people who suffer from cardiovascular disease. In 2004, Anchorage was reclassified a “maintenance” area after being considered a serious carbon monoxide “nonattainment” area for more than 25 years. Fortunately for us, due to a variety of efforts, carbon monoxide concentrations in Anchorage have dropped by approximately 60% since the peak levels experienced in the early to mid-1980’s. Anchorage has not violated the carbon monoxide standard since 1996, is now considered an “attainment area” for carbon monoxide, and has set a plan in place to remain in compliance until 2023.

The most interesting part about carbon monoxide is its source. According to the latest inventory completed for the Anchorage Bowl in 2004, 77% of winter season carbon monoxide pollutants comes from motor vehicle emissions. Cold starts and warm-up idling play a large role in carbon monoxide emissions from vehicles, with this portion of the drive cycle contributing significantly to our CO levels.

The data clearly shows that our driving patterns and transportation choices have a great impact on the level of carbon monoxide we’re exposed to during Alaska’s winter months. However, the good news is that studies show also show that if you park outdoors, plugging-in when its 20 degrees or colder will minimize engine wear, maximize fuel efficiency, and cut carbon monoxide emissions an average of 60% every time you start your automobile. In fact, research out of Canada shows that you improve fuel consumption by 25% by simply plugging-in for the minimum recommended time of two to three hours before driving.