6.1 Challenges and Successes

DEC has successfully transitioned to a fleet of QuantAQ Modulair^TM pods and developed constructive working relationships with the QuantAQ tech support team. Consequently, the volume of data produced by the sensor network has increased substantially, leading DEC to develop efficient quality control (QC) techniques to process, verify, and visualize the greater data throughput.

The DEC team has encountered various several technical, mechanical, and logistical challenges over the reporting period, including:

• The PM₁₀ sensor’s susceptibility to hygroscopic interference; DEC employs automatic data flagging within the AirVision database to nullify erroneously elevated particulate matter readings.

• Various gaseous sensor abnormalities, including ozone (O₃) negative bias, nitric oxide (NO) and nitrogen dioxide (NO₂) low concentration aberrant functions, and O₃ and NO₂sensors reporting mirrored data trends. DEC is working with QuantAQ’s tech support team on these issues.

• Sub-zero wintertime conditions often cause the pods’ data quality to degrade or the pod to shut off. Operating specifications for the QuantAQ Modulair^TM is down to -20°C (-4°F ).

• DEC is still in the process of analyzing collocation data to develop correction factors for the QuantAQ Modulair^TM data, though this is very time consuming and there is limited guidance available from the manufacturer or other sources.

• Mechanical and logistical issues including SD card reader failures, repairing wiring and outlets destroyed by water damage, replacing wiring and power block components that have been stolen or vandalized, or finding a site more representative of community air quality.

• The QuantAQ Modulair^TM pods transmit data over the AT&T and T-Mobile cellular networks. Many rural communities, and much of the interior of the state, do not have compatible cellular coverage or no cellular coverage at all; DEC has had to find alternative communities where QuantAQ Modulair^TM pods can connect to the cellular network.

• Due to the vast size of Alaska and road-system limitations, troubleshooting sensors in rural communities can take much longer than troubleshooting sensors on the road-system. The community contacts often wear many hats and are busy with their day-to-day duties and may not be able to assist with troubleshooting activities.

While the issues discussed above have appeared in one or more pods during the course of network expansion, most of the pods in the network have not experienced any issues. DEC still believes that the QuantAQ Modulair^TM is currently the best suited pod for DEC’s network and provides valuable air quality trend information.

Sensor technology is rapidly evolving with new methods, new devices, and new analytical approaches emerging regularly. DEC conducted a sensor pod comparison study in the winter of ‘22/23 and found that the QuantAQ Modulair^TM performed the best and met many of DEC’s needs, including ease of set-up, responsive communication with the manufacturer, and robust suite of pollutants monitored. DEC is currently researching pods that use different methods of data transmission, such as Wi-Fi or satellite communications. Efforts to identify and purchase alternative air monitoring pods are ongoing, but face limited market options for pods that meet the following criteria: (1) being Wi-Fi or satellite internet compatible; (2) ability to detect at least a majority of the EPA’s designated criteria Pollutantss including PM_2.5 to a sufficient degree of accuracy equivalent or superior to the QuantAQ Modulair^TM; (3) a market price that can reasonably be considered ‘low cost’; and (4) a physical design enabling easy installation, cold weather tolerance, and simple maintenance.

6.2 Data Findings

For data analysis, communities in the sensor network are organized according to general ecoregion. These include the Interior, Western, Southwestern, Southeastern or Panhandle, and Southcentral ecoregions. By grouping sensors into ecoregions, DEC can identify weather and pollution trends affecting one or several ecoregions. Due to the vast size of Alaska, ecoregions may be subdivided into distinct geographic areas; for example, the Southcentral ecoregion can be divided geographically into the Mat-Su Valley area (which includes Anchorage), the Copper River and Chugach Mountain area, and the Kenai Peninsula.

Sensor data can be presented chronologically, to illustrate changes in pollutant concentration over the course of an hour, day, week, month, and year. Time-wise data can be cross-referenced with geographic data to estimate the geospatial movement of air pollution over time and potentially aid in identifying emissions sources. DEC currently uses diurnal and calendar plots to display data in a time-wise manner.

Diurnal plots are useful for comparing changes in pollutant concentration over time in multiple ecoregion (or area within an ecoregion) communities. This facilitates the identification of area- or ecoregion-wide trends in air quality, as well as daily, weekly, or seasonal variation in air quality trends between proximal communities. For example, if pods in an ecoregion show similar PM_2.5 patterns over a given time period, that may indicate a single major emission source, such as a large wildland fire. In contrast, differences in PM_2.5 patterns among ecoregion communities may indicate multiple distinct, localized emission sources.

Calendar plots are useful diagrams for tracking air quality patterns over long periods of time. Each day is represented by a calendar square; daily average PM_2.5 concentrations are calculated and assigned a color code based on the AQI category, where the colors green, yellow, orange, red, purple, and maroon respectively represent “Good”, “Moderate”, “Poor” or “Unhealthy for Sensitive Groups”, “Unhealthy”, “Very Unhealthy”, and “Hazardous” air quality; See Table 3 for a visual representation of the AQI categories. Uncolored calendar squares represent days with <75% data capture. Other incidents may disrupt the sensor’s operation or invalidate its data for one or more days, such as a power outage or a technical issue. By tracking AQI color coding on the calendar plots, DEC can visualize patterns or changes in air quality in specific communities over days, weeks, or months.

Bethel and Napaskiak are two southwestern ecoregion communities each previously outfitted with a QuantAQ Modulair^TM pod. Unfortunately, cellular network compatibility issues emerged in March 2024 and both pods lost connection; both pods regained connection at the end of April 2025. As a result, there is no data to display for the Bethel and Napaskiak communities during the reporting period covered in this document.

The following graphs and figures are all generated with QuantAQ Modulair^TM data.

Figure 1 depicts the time series and diurnal graphs of PM_2.5 concentrations in the Denali NP area and two communities west of Fairbanks, Galena and Nenana, during the reporting period. All communities enjoyed average baseline PM_2.5 levels around 5 µg/m³ for most of the week except for Thursdays, where Galena, and to a lesser degree Denali National Park (NP), saw a spike in PM_2.5. Denali NP and Galena both experienced an increase in PM_2.5 levels during the middle of an average day, whereas Nenana experienced higher PM_2.5 levels in the mornings and evenings, and lower PM_2.5 levels during the middle of the day.

On October 31, 2024, the National Park Service conducted prescribed burning of slash piles near the park headquarters which caused hourly PM_2.5 levels to exceed 150 µg/m³. As this was an intentional event and not indicative of usual background air quality, data from October 31^st was removed from Figure 1.

Galena experienced an increase in its average monthly PM_2.5 level in January, due to a strong inversion at the end of the month. By January 30, temperatures had approached -50°F in Galena, the hourly average PM_2.5 level lingered above 100 µg/m³ for most of the day, with a mid-morning peak of 340 µg/m³. This inversion event substantially increased the early morning hours, Thursday, and January PM_2.5 averages compared to the other weekdays and winter months, which generally had very low PM_2.5 levels.

Figure 2 depicts the time series and diurnal graphs of PM_2.5 concentrations in several eastern Interior region communities proximal to Fairbanks; Goldstream to the northwest, and Delta Junction and Tok to the southeast. For the most part, Delta Junction and Goldstream experienced ‘Good’ (AQI) air quality, with levels typically staying below 3 µg/m³. Tok experienced a higher baseline average PM_2.5 level closer to 5 µg/m³, as well as significantly higher PM_2.5 levels on Fridays and Saturdays. All communities experienced a relative increase in PM_2.5 level in January, potentially to cold weather inversions that trapped emissions from vehicles and buildings at ground level. A particularly extreme cold spell at the start of the year created inversion events across the Interior on January 2-3, with temperatures exceeding -30°F in Delta Junction and -40°F in Tok. During the inversions, Delta Junction reached a peak hourly PM_2.5 average of 120 µg/m³, and Tok reached a peak hourly PM_2.5 average exceeding 300 µg/m³.

Tok’s elevated wintertime PM_2.5 levels are likely due to the local geography. The Tok community is located in the middle of a valley adjacent to the eastern foothills of the Alaska Range. Cold air moving down from the snow-capped mountains moderates the temperature in the valley, making Tok somewhat cooler than other Interior communities like Delta Junction or Fairbanks. In the winter, this contributes to the frequent formation of ice fog and inversion events, which trap emissions at the ground level.

Figure 3 depicts the time series and diurnal graphs of PM_2.5 concentrations for Kotzebue and Nome, two communities in the Western ecoregion. Over the course of an average day, both communities see PM_2.5 levels spike during morning and afternoon hours. Over the course of the week, both communities exhibit elevated PM_2.5 levels during the first half of the work week, with concentration levels falling down to below 3 µg/m³ for the second half of the work week and the weekend. PM_2.5 levels were generally low in the autumn and early winter months but spiked in January as temperatures dropped and home heating activities increased.

On January 18^th, the Anchorage-based telecommunications service provider Quintillion Global announced that one of their undersea cables servicing the north slope and northwest communities had been severed by sea ice. Due to the cable damage, cellular service in the area was affected and the QuantAQ Modulair^TM pod in Kotzebue lost contact with both DEC and QuantAQ servers. At the time of this report, the cable has not been repaired and cellular service has not been restored.

Figure 4 depicts the time series and diurnal graphs of PM_2.5 concentrations for Chickaloon, Palmer, and Wasilla in the eastern Mat-Su Valley area and Glennallen in the Copper River Valley area. Generally, these communities have ‘Good’ (AQI) air quality and relatively little diurnal variation over an average day and week. Notable features of historical PM_2.5 levels include concentration spikes on Friday and Saturday mornings in Glennallen, spikes on Wednesday and Sunday evenings in Wasilla, and spikes on Friday afternoon in Chickaloon and Palmer. Over the course of the reporting period, all communities maintained low average PM_2.5 levels.

Figure 5 depicts the time series and diurnal graphs of PM_2.5 concentrations for several southcentral communities in the western Mat-Su Valley area: Big Lake, Campbell Creek Science Center (CCSC ) in Anchorage, Talkeetna, and Willow. Generally, these communities have ‘Good’ (AQI) air quality. For all communities, there was little variation in PM_2.5 levels over the course of an average week; moderate rises in PM_2.5 were seen on the weekends, but overall variation was minimal. Over the interim reporting period, these communities experienced an initial rise in PM_2.5 levels, potentially corresponding to colder temperatures and increasing use of home heating devices in the early winter.

Figure 6 depicts the time series and diurnal graphs of PM_2.5 concentrations for communities on the Kenai Peninsula. With the exception of Ninilchik, these communities show similar weekly trends in PM_2.5 concentration, characterized by relatively steady levels for the first half of the week, which slowly decrease over the latter half of the week. In Homer, PM_2.5 levels are consistently at their lowest on Sundays. Daily PM_2.5 concentration shows more variation, with Homer, Seward, and Soldotna experiencing a typical pattern of higher levels in the mornings and evenings and lower levels during midday. Ninilchik experienced a muted daily and weekly pattern, with PM_2.5 levels showing gradual increases in the evenings, and slightly higher average levels on Mondays, Tuesdays and Saturdays. Overall, PM_2.5 levels in Ninilchik remained quite low, with hourly and daily averages never exceeding 2 µg/m³. All communities on the Kenai Peninsula recorded very low PM_2.5 concentrations over the reporting period.

The Soldotna data for the month of February is not representative, as the pod’s PM_2.5 sensor went offline from February 5-14^th.

Figure 7 depicts the time series and diurnal graphs of PM_2.5 concentrations for the southern gulf coast communities of Cordova and Kodiak. Both communities generally have ‘Good’ (AQI) air quality. Kodiak exhibits relatively low diurnal variation in PM_2.5 levels across an average day and week, whereas Cordova demonstrates more variability, including PM_2.5 spikes during the morning and afternoon hours, as well as a distinct rise in PM_2.5 on Mondays and later in the work week. Kodiak saw an increase in PM_2.5 levels over the course of the interim reporting period, though both communities maintained very low mean PM_2.5 concentration levels over the reporting period.

Due to a roof leak and reconstruction at the host building, the Kodiak pod was taken offline on March 6, 2025, and moved to a secure location. The pod was not reconnected until April 8, after the end of the interim reporting period. As a result, the apparent increase in PM_2.5 levels in March is not an accurate representation of the community air quality. The re-installed Kodiak pod was only active for the first week of March and detected elevated PM_2.5 over two of those nights which produced a skewed monthly average.

Due to technical and performance issues, the original Cordova pod was taken down and replaced with a new pod on January 23, 2025.

Figure 8 depicts the time series and diurnal graphs of PM_2.5 concentrations for Haines and Skagway. Daily PM_2.5 concentrations are generally similar in both communities, with baseline levels staying below 3 µg/m³, although the daily patterns appear to be different. Skagway exhibits a typical pattern of PM_2.5 spikes at the start and end of the workday, and an increase in PM_2.5 on Fridays and Saturdays. Haines appears to follow a similar but more pronounced pattern; PM_2.5 levels rise in the morning hours but stay elevated during midday and spike higher in the evening before dropping down at night. Skagway observed decreasing PM_2.5 levels over the reporting period, whereas Haines experienced an increase in average PM_2.5 levels later in the reporting period, likely due to two days with moderately elevated midday PM_2.5 in mid-February. Both communities experienced very low mean PM_2.5 concentrations over the reporting period.

On October 5^th, a structure fire occurred about 580 meters from the Haines sensor. Hourly PM_2.5 averages approached 300 µg/m³. This event significantly skewed Haines’ PM_2.5 data over the interim period so data from October 5^th and 6^th have been removed from Fig. 8 to show more representative ambient air quality in Haines during the reporting period.

Figure 9 depicts the time series and diurnal graphs of PM_2.5 concentrations for Hoonah, Juneau, and Sitka, three communities in the northern part of the Southeast ecoregion. Hoonah and Sitka exhibit similar patterns of PM_2.5 concentration across different temporal scales, while Juneau maintains both a low concentration and low diurnal variation of PM_2.5. Juneau experiences small increases in PM_2.5 concentration during the morning and evening hours during the first half of the week, but only evening surges in the latter half of the week. Overall levels in Juneau were remarkably low, with hourly PM_2.5 averages typically below 2.5 µg/m³. PM_2.5 variation across the week is minimal, with Sitka seeing an average increase on Thursdays, while Hoonah reaches a PM_2.5 concentration low on Saturdays. Both communities experienced increasing PM_2.5 levels as the winter progressed, with Sitka experiencing a monthly average peak in January, and Hoonah in February.

Figure 10 depicts the time series and diurnal graphs of PM_2.5 concentrations for Ketchikan and Wrangell, two communities near the southern tip of the Southeast ecoregion. Both communities demonstrate similar patterns in PM_2.5 concentration trends, with spikes seen in the morning and evening. Ketchikan has slightly higher (0.5-1.0 µg/m³) average PM_2.5 levels over the week, and experienced higher peak PM_2.5 levels, particularly in the evenings. Both communities demonstrate a trend of higher PM_2.5 levels on Sunday and Monday than most weekdays. PM_2.5 levels in Ketchikan were elevated in February, potentially due to increased home heating emissions due to the cold weather.

Figure 11 and Figure 12 depict calendar plots for the Badger Road area during the reporting period. For much of the period, air quality in the Badger Road area remained in the ‘Good’ AQI range. However, the Badger Road area experienced poorer air quality on several occasions, potentially due to extreme cold temperatures throughout the winter that created inversion conditions that trapped particulates at the ground level, leading to daily averages that reached the ‘Moderate’ AQI range. The most severe cold weather incidents occurred at the end of November going into December, and again at the end of December going into January, where AQI levels reached ‘Unhealthy for Sensitive Groups’.

Figure 13 and Figure 14 depict calendar plots for the community of Delta Junction during the reporting period. For much of the reporting period, air quality in Delta Junction remained in the ‘Good’ AQI range. Across the reporting period, only four days reached the ‘Moderate’ AQI level; each incident corresponds to extreme cold weather events and inversion conditions in Delta Junction, where emissions from vehicles and home heating equipment cannot easily disperse in the atmosphere and instead accumulate in the community air space at ground level. The multi-day outage in late January was due to strong winds that may have knocked over trees, leading to power outages in the region.

Figure 15 and Figure 16 depict calendar plots for the Denali NP pod during the reporting period. Denali NP enjoyed air quality in the ‘Good’ AQI range for nearly the entire reporting period, with only a single day at the ‘Moderate’ AQI level. On October 31^st, 2024, the Denali NP Fire Crew executed a study on slash pile burn techniques. This involved burning multiple large piles of plant debris at several locations near the Denali NP Headquarters and the air sensor. The pod detected a temporary spike in PM_2.5 levels above 600 µg/m³, which raised the daily average into the ‘Moderate’ AQI range. The slash pile burn study was an isolated event; it is not regularly occurring and does not have seasonal or recurrent effects on air quality in Denali NP.

Figure 17 and Figure 18 depict calendar plots for the Goldstream area during the reporting period. For much of the period, air quality in Goldstream remained in the ‘Good’ AQI range. The air monitor is installed at a recreational sports store, which sometimes has large crowds and idling vehicles in its parking lot for athletic events or equipment sales. On October 2^nd-3^rd, the sports store hosted the bib pick-up for a popular community race; heavy vehicle and pedestrian traffic kicked up a lot of dust, leading to daily averages in the ‘Moderate’ AQI range. The Goldstream pod experiences occasional outages due to the air monitor sharing a popular electrical outlet. During the occasional outages, DEC reached out to contacts at the sports store to request a power cycle or outlet reset, which was typically sufficient to get the pod back online.

Figure 19 and Figure 20 depict calendar plots for the community of Tok during the reporting period. For much of the period, air quality in Tok remained in the ‘Good’ AQI range, although the community’s geographic location makes it susceptible to inversion events. A period of extremely cold weather at the end of December and beginning of January lead to a strong inversion event, which trapped air pollution at ground level resulting in drastically elevated PM_2.5 levels in Tok for four days. The event peaked on January 3^rd when PM_2.5 levels reached the Very Unhealthy’ AQI range. January 4^th reported ‘Unhealthy’ AQI levels, and air quality had returned to ‘Normal’ AQI by January 5^th. The single-day outage in late January was due to strong winds that may have knocked over trees, leading to power outages in the region. On February 26^th, the pod experienced operational issues and failed to generate sufficient data to calculate a daily PM_2.5 average.

Due to performance issues, the original pod at Tok (MOD 444) was replaced (by MOD 653) on December 2^nd, 2024; the replacement pod came online quickly, so the pod swap did not significantly disrupt data collection.

Figure 21 and Figure 22 depict calendar plots for the community of Nenana during the reporting period. Nenana generally has air quality in the ‘Good’ AQI range. December 15^th and January 1^st and 15^th saw very cold temperatures leading to increases in PM_2.5 levels into the ‘Moderate’ AQI range. On March 1^st, Nenana hosted the Tripod Days event, which is a special event celebrating warming temperatures and the onset of spring. This event involved an influx of visitors to Nenana, several outdoor community activities, and increased vehicle and pedestrian traffic, which contributed to pushing local air quality into the ‘Moderate’ AQI range. On November 4^th, the pod experienced operational issues and failed to generate sufficient data to calculate a daily PM_2.5 average.

Figure 23 and Figure 24 depict calendar plots for the community of Galena during the reporting period. Generally, Galena experiences good air quality with daily averages in the ‘Good’ AQI range. In January, Galena experienced several days with air quality in the ‘Moderate’ AQI range, and a day with average air quality in the ‘Unhealthy’ AQI range. On each of these dates, Galena was experiencing very cold weather and inversion conditions, which trapped pollutants at ground level and raised local PM_2.5 levels. January 30^th saw the most extreme cold temperatures, the strongest inversion conditions, and the highest PM_2.5 levels of any day in the month. On December 13^th, the pod experienced operational issues and failed to generate sufficient data to calculate a daily PM_2.5 average.

Figure 25 and Figure 26 depict calendar plots for the community of Kotzebue during the reporting period. On August 14^th, near the end of the previous interim reporting period, the QuantAQ Modulair^TM pod was taken down and reinstalled in a new location due to construction activities. The pod was re-activated on October 11^th and generated enough data to begin calculating daily averages on October 12^th. The pod experienced an outage from November 17^th-25^th due to a large blizzard in the area that disrupted power lines. The pod experienced another outage from December 22^nd-30^th, likely due to the power cable being accidentally unplugged. The second week of January saw a drop in temperature which was simultaneous with an increase in PM_2.5 levels that peaked on January 14^th in the ‘Unhealthy’ AQI range.

The pod suddenly went offline on the morning of January 17^th due to a severed subsea cable off the western coast of Alaska. Quintillion’s network hosts several internet and cellular providers, including AT&T (which the QuantAQ Modulair^TM pods use to transmit data), which all saw disruptions to their service due to the cable break. At the time of this report, the cable has not been repaired and cellular service has not been restored.

Figure 27 and Figure 28 depict calendar plots for the community of Nome during the reporting period. For the most part, Nome enjoyed air quality in the ‘Good’ AQI range. In late January, Nome experienced a multi-day cold spell with inversion conditions that peaked on January 29^th before returning to normal, which was paired with a simultaneous increase in PM_2.5 levels into the ‘Moderate’ AQI range.

Figure 29 and Figure 30 depict calendar plots for the island-based community of Kodiak during the reporting period. Kodiak generally enjoys air quality in the ‘Good’ AQI range, although several days had air quality in the ‘Moderate’ AQI range.

Due to a roof leak and construction at the host building, the Kodiak pod was taken offline on March 6^th, 2025, and moved to a secure location. The pod was not reconnected until April 8^th, after the end of the interim reporting period.

Figure 31 and Figure 32 depict calendar plots for the community of Big Lake during the reporting period. Big Lake enjoyed ‘Good’ (AQI) air quality for most of the reporting period, although there were several days and multi-day periods with air quality in the ‘Moderate’ AQI range. In November, December, and February, all the ‘Moderate’ AQI days occurred during below-freezing temperatures and were characterized by thick mist and ice fog. A community contact reported that ice fog in November was so thick, it impaired visibility and posed safety risks for drivers and pedestrians. On February 15^th-16^th, the pod experienced operational issues and failed to generate sufficient data to calculate daily PM_2.5 averages.

Figure 33 and Figure 34 depict calendar plots for the Campbell Creek Science Center located in east Anchorage during the reporting period. The Campbell Creek Science Center pod experienced air quality in the ‘Good’ AQI range for almost the entire reporting period, except for December 16^th, where the air quality reached the ‘Moderate’ AQI range.

Figure 35 and Figure 36 depict calendar plots for the community of Chickaloon/Sutton-Alpine during the reporting period. The air sensor is located closer to the community of Sutton-Alpine but is located at a building whose mailing address corresponds to the community of Chickaloon. Chickaloon/Sutton-Alpine enjoyed air quality in the ‘Good’ AQI range for almost the entire reporting period, except for a single day in October. In the autumn before snowfall, communities in the region were affected by widespread wind-blown dust which worsened local air quality. On October 18^th, this wind-blown dust degraded Chickaloon/Sutton-Alpine’s air quality into the ‘Moderate’ AQI range.

Figure 37 and Figure 38 depict calendar plots for the community of Talkeetna during the reporting period. The Talkeetna pod measured air quality in the ‘Good’ AQI range for the entire duration of the reporting period.

Figure 39 and Figure 40 depict calendar plots for the community of Palmer during the reporting period. Palmer generally had air quality in the ‘Good’ AQI range for almost the entirety of the reporting period, except for a single day each in November and January that had ‘Moderate’ (AQI) air quality.

Figure 41 and Figure 42 depict calendar plots for the community of Wasilla during the reporting period. In the autumn before snowfall, communities in the region were affected by widespread wind-blown dust which worsened local air quality. On October 18^th, this wind-blown dust degraded Wasilla’s air quality into the ‘Moderate’ AQI range. Wasilla enjoyed ‘Good’ (AQI) air quality for the rest of the reporting period.

Figure 43 and Figure 44 depict calendar plots for the community of Willow during the reporting period. Willow generally enjoyed ‘Good’ (AQI) air quality through the reporting period, with occasional days in the ‘Moderate’ AQI range. November 12^th was a cool day heading into a cold spell, characterized by mist and freezing fog. PM_2.5 levels peaked at midday, raising the daily average to ‘Moderate’, but air quality was otherwise in the ‘Good’ AQI range. Over several days before and after New Year’s Eve, Willow experienced a cold spell that brought more mist and freezing fog. Elevated PM_2.5 levels were likely due to increased home heating during the cold snap.

On January 12^th, the pod experienced three power outages that interrupted data collection for slightly over half the day, meaning a daily average could not be calculated.

Figure 45 and Figure 46 depict calendar plots for the community of Tyonek during the reporting period. The pod was installed on November 20^th and began calculating daily averages by the 21^st. Tyonek generally has ‘Good’ (AQI) air quality, with occasional escalations into the ‘Moderate’ AQI range, particularly during cold weather. The installation took place in the middle of a cold spell; the first three days after installation had ‘Moderate’ (AQI) air quality. After a warm weekend, another cold spell hit at the end of the month, producing ‘Moderate’ (AQI) air quality on November 29^th. In December and January, relative increases in PM_2.5 levels corresponded to dips in temperature. These temperature-related spikes in PM_2.5 were likely due to increased home heating use in response to the cold. After the last cold day with ‘Moderate’ (AQI) air quality in February, the pod measured ‘Good’ (AQI) air quality for the remainder of the reporting period.

The outage in mid-January was due to a power disruption, when the pod’s power cord was unplugged by a community resident performing snow clearing. The pod was offline from January 12^th to January 16^th.

Figure 47 and Figure 48 depict calendar plots for the community of Yakutat during the reporting period. The pod was installed on October 24^th and began calculating daily averages by the 25^th. Yakutat enjoyed air quality in the ‘Good’ AQI range the entire time the pod was operational in 2024.

The outage on January 16^th and 17^th may have been caused by trees falling on power lines, as there were strong winds in the area around this time, and many regional power outages were reported.

Figure 49 and Figure 50 depicts a calendar plot for the community of Cordova during the reporting period. The initial pod installation site did not have a reliable power supply; the pod was connected to an outlet regulated by a power switch that was often turned off, leading to frequent disruptions to pod operation. DEC worked with the community contact to find a more reliable power supply option, and the pod was reconnected at the start of 2025. Unfortunately, the pod experienced recurrent issues with its SD card and port that required it to be taken down and replaced (by MOD 667) on January 23^rd. The original pod, MOD 664, was subsequently sent back to the manufacturer for repairs. There was a prolonged cold spell in late January and early February that brought mist, snow and hail, and corresponded with higher levels of PM_2.5, pushing air quality into the ‘Moderate’ AQI range for several days potentially due to increased home heating activities. Cordova enjoyed ‘Good’ (AQI) air quality for the remainder of the reporting period.

Figure 51 and Figure 52 depict calendar plots for the community of Glennallen during the reporting period. Near the end of 2025 and beginning of 2025, Glennallen experienced multiple extreme cold spells that exceeded -30 F and occasionally created inversion conditions. November 30^th and January 3^rd were both extremely cold days characterized by a morning surge in PM_2.5 levels. The morning PM_2.5 surge quickly subsided and PM_2.5 levels returned to baseline by midday, but the surge pushed the daily average into the ‘Moderate’ AQI range. The pod’s PM_2.5 and PM₁₀ sensors experienced technical difficulties in mid-January during a bout of warmer weather; as a result, the pod was unable to calculate daily averages on January 12^th, 25^th, and 26^th.

Figure 53 and Figure 54 depict calendar plots for the community of Homer during the reporting period. Homer experienced air quality in the ‘Good’ AQI range for the entire duration of the reporting period.

The pod’s power outlet shut off for an unknown reason on January 16, and was not turned back on until February 10, when the pod re-connected and resumed normal operation.

Figure 55 and Figure 56 depict calendar plots for the community of Ninilchik during the reporting period. The Ninilchik pod measured ‘Good’ (AQI) air quality and experienced no major outages or significant disruptions to data collection for the entire duration of the reporting period.

Figure 57 and Figure 58 depict calendar plots for the community of Kenai during the reporting period. The pod was installed November 19^th and began calculating daily averages on the 20^th. For almost the entirety of the 2024-2025 wintertime reporting period, Kenai enjoyed air quality in the ‘Good’ AQI range, except for a few days in January with ‘Moderate’ (AQI) air quality. The increase in PM_2.5 levels observed on January 30^th and 31^st occurred during a cold spell. PM_2.5 spikes occurred throughout the day on the 30^th, leading to a large spike early on the morning of the 31^st that skewed the daily average into the ‘Moderate’ AQI range. These spikes could potentially be attributed to an increase in home heating use during the cold spell.

Figure 59 and Figure 60 depict calendar plots for the community of Seward during the reporting period. Seward enjoyed ‘Good’ (AQI) air quality for almost the entirety of the reporting period, except for several ‘Moderate’ AQI days in January. Each ‘Moderate’ AQI day appears to have been affected by a nighttime surge in hourly PM_2.5 levels that gradually returned to baseline.

Figure 61 and Figure 62 depict calendar plots for the community of Soldotna during the reporting period. For the most part, Soldotna enjoyed ‘Good’ (AQI) air quality throughout the entirety of the reporting period. There was a 10-day outage in mid-February, caused by technical issues with the PM_2.5 and PM₁₀ sensors. Gaseous sensors remained online and operational during the PM sensor outage. Due to the PM sensor technical issues precluding data collection, daily averages for February 5^th through the 14^th could not be calculated.

Figure 63 and Figure 64 depict calendar plots for the community of Haines during the reporting period. For most of the reporting period, Haines had ‘Good’ (AQI) air quality. Several days near the beginning of the reporting period had air quality in the ‘Moderate’ AQI range. In the last four hours of October 5^th, there was a simultaneous surge in CO, PM_2.5 and PM₁₀ levels caused by a large building fire in downtown Haines. In mid-November, Haines experienced a prolonged bout of wind-blown dust. This raised PM_2.5 and PM₁₀ levels across multiple days, with November 18^th and 19^th reaching the ‘Moderate’ AQI range.

Figure 65 and Figure 66 depict calendar plots for the community of Skagway during the reporting period. Skagway is a very busy tourist destination in the summer but sees little activity in the winter. The Skagway pod measured air quality in the ‘Good’ AQI range for the entire duration of the reporting period.

Figure 67 and Figure 68 depict calendar plots for the 5^th Street site pod in Juneau during the reporting period. The pod in Juneau at 5^th Street measured air quality in the ‘Good’ AQI range for the entire duration of the reporting period.

Figure 69 and Figure 70 depict calendar plots for the State Museum site pod in Juneau during the reporting period. The pod in Juneau at the State Museum measured air quality in the ‘Good’ AQI range for the entire duration of the reporting period.

Figure 71 and Figure 72 depict calendar plots for the community of Hoonah during the reporting period. Most days enjoyed air quality in the ‘Good’ AQI range, although air quality frequently entered the ‘Moderate’ AQI range. A community contact reported that on days with little to no wind, they frequently observe smoke, fog, and exhaust fumes lingering in the area. The frequency of ‘Moderate’ AQI days may be partially a consequence of the Hoonah sensor being installed near the chimneys and heating exhaust ports of nearby homes; when home heating activities increase, Hoonah typically sees a rise in PM_2.5 levels.

Figure 73 and Figure 74 depict calendar plots for the community of Sitka during the reporting period. For most of the reporting period, Sitka had ‘Good’ (AQI) air quality, with the occasional day in the ‘Moderate’ AQI range. The first two weeks of February had below-freezing temperatures and an increase in home heating use, leading to increased PM_2.5 levels and ‘Moderate’ (AQI) air quality.

Figure 75 and Figure 76 depict calendar plots for the community of Ketchikan during the reporting period. For most of the reporting period, Ketchikan had ‘Good’ (AQI) air quality with the exception of several days in February. The first half of the month saw consistent below-freezing temperatures and increased PM_2.5 levels likely caused by an increase in home heating use. Near the end of the month, Ketchikan enjoyed warmer temperatures and lower PM_2.5 levels. February 23^rd saw a very brief PM_2.5 spike around 9 PM which pushed the daily average into the ‘Moderate’ AQI range, despite PM_2.5 levels staying below 7 µg/m³ for most of the day.

Figure 77 and Figure 78 depict calendar plots for the community of Wrangell during the reporting period. For most of the reporting period, Wrangell had ‘Good’ (AQI) air quality. Wrangell experienced a cold spell near the end of November which was linked with spikes in both PM_2.5 and PM₁₀. The increase in PM could potentially be attributed to an increase in home heating use.

On November 12^th, the pod experienced technical issues with the PM_2.5 and PM₁₀ sensors which prevented the calculation of a daily average. Gaseous sensors remained online and operational during the PM sensor outage.