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DEC Releases 2019 Juneau air quality monitoring results

  • For immediate release — June 10, 2020
  • Contact: Barbara Trost, 907-269-6249

Juneau, AK — The air quality in downtown Juneau was generally good during the summer 2019 cruise ship season according to a study by the Alaska Department of Environmental Conservation (DEC). While there were some short, observable periods in the data that appear to tie to cruise ship emissions, generally cruise ships did not increase air pollution to levels of concern.

"There are a lot of factors that can contribute to downtown Juneau’s air quality in the summer because it’s a busy area," said Alice Edwards, Air Quality Division Director. "These include food carts, busses, taxis, and local traffic, as well as the cruise ships. There were also open burns and summer road construction last summer. While all of these sources contribute to air pollution, the data show that they didn’t create an overall atmosphere of poor air quality downtown."

DEC conducted the air quality study using a tightly-spaced grid of low-cost, non-regulatory PurpleAir PA-II monitors, which measure fine particulate matter (PM2.5), throughout downtown Juneau and "the flats" (the neighborhood between 9th and 12th streets). PM2.5 is considered a good indicator of cruise ship emissions, and the study was designed to identify areas of high, medium, and low impact. Air quality was characterized using EPA Air Quality Index (AQI) classifications, which range from "Good" to "Hazardous" based on the measurable pollution in the air.

Only a few full days had air quality ratings of "Moderate" to "Unhealthy for Sensitive Groups" during the season, and these were attributed to smoke from wildfires in British Columbia. There were periods of one or two hours observed at times throughout the summer when air quality fell below the "Good" category. Staff looked at meteorological data and web cam footage and found that these periods often aligned with cruise ships maneuvering in and out of the port, which requires heavier engine use than when they are tied up.

Early in the 2019 cruise season, cruise line companies worked together to reduce their impacts on Juneau air quality by implementing changes aimed at reducing emissions. These changes included reducing idle times in the harbor and switching to a low sulfur marine fuel while in port.

"It is difficult to compare Juneau’s 2019 air quality to that of previous years because we didn’t have monitoring equipment in place before last summer," said Edwards. "However, DEC received fewer complaints from Juneau residents during the 2019 season than in the previous two years."

With minimal cruise ship activity in 2020 as a result of the Covid-19 pandemic, DEC has a rare opportunity to establish a baseline for air quality impacts from all of the sources that support the summer cruise season in downtown Juneau. This summer DEC will deploy survey grade sensor pods, which are expected to produce more accurate and precise PM2.5 data, as well as SO2 data at one hour resolution in order to detect short term air impacts. Like PM2.5, SO2 is also a good indicator of emissions from cruise ships and other vehicles.

Juneau Air Quality Monitoring Project web page

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