America’s most polluted city?
Fairbanks, Alaska has made it into the news several times for being one of the US’ highest polluted cities in winter. But what about the remote areas, far out of Fairbanks? Is there an escape from air pollution?
Air quality in remote areas
Most of the villages in Interior Alaska are located in valleys. In these valleys, inversions frequently form due to radiative cooling. This means that during clear nights more energy is lost to space than is gained during the day from the sun. The air close to the soil cools faster than the air above. Thus, after sunset the air on the slopes cools faster than the air at same height over the valley. Cold air is heavier than warm air at same moisture and pressure. Consequently, the cold air flows down the slopes into the valley. This process leads to cold air under warm air. The result is opposite to the normal behavior of temperature in the lower 5 to 6 miles (about 8-10 km) of the atmosphere, and is known as an inversion. Typically, temperature decreases with height, while during inversions it increases with height.
Unfortunately, when heavy air lays under light air mixing and exchange of air from aloft are suppressed. Consequently, any emissions into the inversion stay there. During winter under high pressure conditions, wintertime inversions in Interior Alaska may exist for multiple days. Then the pollutants can accumulate to unhealthy concentrations.
Space heating by wood is very common
In Interior Alaska, wood and/or coal is used for heating in the villages in winter. Power is produced typically by diesel generators. Some villages have a small wind turbine, but one needs wind to produce wind energy, i.e. backup is from fossil fuel. Trash is usually burned locally. In villages off the Alaska road network, traffic emissions only stem from air-crafts, cars and equipment within the village plus snow machines in winter, and motor-boots in summer. For villages on the road network add vehicle emissions from traffic to and from the village for shopping and by tourists. So far to the anthropogenic emissions.
Wildfires lead to poor air quality in summer
In summer, smoke may occur from the wildfires that are a natural component of the taiga ecosystem of Interior Alaska. If the wildfire is very close and/or large to where you stay, canoe or hike, air pollution may be very large for natural reasons! However, far away from the wildfires and in years with weak fire seasons remote Interior Alaska has very pristine air, and is vacation for the lungs.
Take-home message: Wildfires are natural events that may pollute the otherwise pristine air of remote Interior Alaska. The settlements and cities may be local pollution hot spots in winter and/or under inversion conditions.
Learn about Fairbanks air quality problem at the link.
Look of the day
I wore the outfit shown in the photos above to a work diner the other day. I centered the outfit around the brown and orange hues of the scarf that was a thrift-store find for $20 some years ago. The belt breaks the upper part of the outfit in two and serves to create a waist on my boyish body. Highlighting the waist is needed as the boot toppers visually shorten the legs. Together the proportions look just right.
The photos in the middle and at the end of the post show some interesting, hardly visible details of the tights, and details of the scarf and belt. Can you believe that I found this silk Gucci scarf for $20 in a consignment store?
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Photos: G. Kramm
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