Programs & Planning
Air Quality

David Wallace
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ACHD is aware of the significant factor vehicles and vehicular activities play in the quality of Ada County's air quality. Ada County follows federal and state regulations and meets or exceeds requirements to keep the air quality at its best possible level. ACHD complies with new standards as they are implemented.

ACHD Commuteride also helps improve air quality by promoting alternatives to driving alone.    Click here for details.

Two types of air quality pollutants are currently of concern in Ada County: Carbon Monoxide and Particulate Matter. These are discussed below and ACHD's air quality management strategies are briefly summarized (a third type, ozone, is currently being monitored by the Idaho Department of Environmental Quality).

Click here for today's air quality report!


Carbon Monoxide

Carbon monoxide is a colorless, odorless gas. It interferes with the ability of blood to transport oxygen to organs and tissue throughout the body. This can cause slower reflexes, confusion, and drowsiness. It can also reduce visual perception and coordination, and decrease the ability to learn.

Carbon monoxide is produced by burning fossil fuels such as gasoline, diesel, natural gas, fuel oil, or coal, especially when combustion is incomplete. Wood burning, agricultural burning, industrial combustion and forest fires also produce carbon monoxide. Carbon monoxide levels are generally highest in areas with traffic congestion and poor air circulation (like a busy downtown street with tall buildings during rush hour).

ACHD is aware that higher levels of carbon monoxide are emitted from automobiles as they are idle at stop lights throughout the county. With this in mind, ACHD's Traffic Management Center actively works to make the wait time at traffic signals as short as possible. By moving traffic along in a coordinated and efficient manner throughout the county, carbon monoxide levels are reduced.


Particulate Matter

Particulate matter is made up of small particles suspended in air. The human body's respiratory system can not filter out particles smaller than 10 microns. These particles (PM10) can reach deep into lung tissue, causing increased respiratory disease, lung damage, and possibly premature death. They can aggravate existing respiratory or cardiovascular disease and impair the body's defense system, causing greater susceptibility to disease. Some types of particles are carcinogenic. There is also a strong correlation between PM10 levels and infant mortality.

A subset of particulate matter is PM2.5, particles of 2.5 microns or less. While PM10 has serious health implications, the particles that make up this smaller size range have been found to be most damaging.

In 1997, the EPA slightly relaxed the PM10 standards and began the process to add new, stringent PM2.5 standards to reflect new health studies.

Particulate matter is composed of several substances. The largest portion consists of soil or dust that becomes airborne due to vehicles, wind, construction or agricultural activities. It also comes from burning fossil fuels (e.g., gasoline, diesel, natural gas, fuel oil, and coal), smoke or ash from wood burning, agricultural burning, or forest fires. Ammonium nitrate and ammonium sulfate are extremely fine particles that result from chemical reactions in the air. These particles are made up of ammonia from livestock operations and oxides of nitrogen and sulfur from burning of fossil fuels.

Because vehicles that travel Ada County's roadways contribute directly to the particulates in the air, ACHD continuously works to help make the roads less traveled. There are numerous ways that this is accomplished. One such way is to route traffic along arterial and collector streets to get people from their point of origin to their destination via the shortest and quickest possible route. ACHD also actively sponsors and promotes its Commuteride program to physically reduce the number of vehicle using the county's roadways. The ACHD Maintenance & Operations Division also aggressively uses its Street Sweeping Program to reduce the amount of dirt and sand that is present on the county's streets.