Approach/Scope

Develop an approach for screening near real-time surface and remote sensing monitoring data for potential exceptional event contributions to air quality problems in the LADCO states. The following workflow is being used by LADCO for screening air quality data.

  • Airnow Tech is the first tool to use for this triage analysis.
  • LADCO will identify the days where MDA8 O3 > 70 ppb at each monitor, and highlight the top days that are contributing to the design value
  • Analysis will focus on identifying if there could be smoke enhancements on the high days and DV days at the violating monitors
  • Discussion questions:
    • How to bring in PM2.5 and CO, other pollutants?
    • What are the next steps after potential days are identified

Methods

The LADCO Exceptional Event screening analysis focused on finding signals in standard surface monitoring data to identify when there is potential for smoke influences on surface air quality conditions during the ozone season (April 1 – October 31). We looked at associations between AQS observations of daily maximum 8-hour ozone (DM8h O3) and daily maximum 8-hour average CO (DM8h CO); and CASTNet daily average total PM2.5 (DA PM25).  Our hypothesis is that coincident peaks in all three of these pollutants may indicate smoke influence in a non-attainment area (NAA).

For each region of interest (e.g., 2015 O3 NAAQS NAA) we display three plots:

  • Average Standardized Log-transformed Timeseries – Plots show O3, CO, and PM2.5 concentration anomalies for the NAA during the 2018 ozone season. These plots summarize the ‘Monitor-specific Standardized Log-transformed Timeseries’ plots below and were created by averaging the standardized timeseries across all monitors within the NAA. Standardization (i.e., normalization) was done using the monthly mean and standard deviation of the log-transformed observed values at each site over the 2013-2017 period.
  • Monitor-specific Standardized Log-transformed Timeseries – Plots show O3, CO, and PM2.5 concentration anomalies at individual monitors in the NAA during the 2018 ozone season. Standardization (i.e., normalization) was done using the monthly mean and standard deviation of the log-transformed observed values at each site over the 2013-2017 period.
  • Concentration Residuals – Plots show O3, CO, and PM2.5 concentrations above the mean +1 standard deviation at individual monitors in the NAA.

All of the plots are overlaid with grey shading to indicate when the HMS smoke product qualitatively shows smoke plumes in the vicinity of the NAA. Click on a plot to expand to a full browser window.

We tested and validated this approach using monitoring and smoke data from 2016. The results for 2016 are shown below. In subsequent sections of this site, we present screening analysis for more recent years.

2016 EE Screening Results


Results

2024 Analysis and Call Notes

Objectives of the 2024 EE workgroup:

  1. Updated the LADCO O3-PM2.5-CO anomaly metric to use a 5-year rolling average rather than a fixed period average. Specifically, 2024 EE data was normalized by monthly mean and standard deviation recorded in 2019-2023 period (completed in May 2024).
  2. Conduct exploratory analysis for PM2.5 EE screening metrics for determining indicator variables and anomaly values for fire smoke influence on PM2.5 concentrations (ongoing)
  3. Develop a prototype integrating the 72-hour transport distance and direction at monitors to provide fire source location information for EE screening
  4. Conduct exploratory analysis for a potential use of visibility data for PM2.5 EE screening
  5. Prototype (and possibly deploy) an algorithm for identifying similar meteorological days as to contrast the smoke-influenced days using a Classification & Regression Analysis Tree (CART) and Self-organizing Map (SOM) analyses

2024 EE Screening Results (data retrieval on May 30, 2024)


2023 Analysis and Call Notes

Objectives of the 2023 EE workgroup:

  1. Updated the LADCO O3-PM2.5-CO anomaly metric to use a 5-year rolling average rather than a fixed period average. Specifically, 2023 EE data was normalized by monthly mean and standard deviation recorded in 2018-2022 period (completed in Apr 2023).
  2. Automated the process of integrating HMS smoke information and AirNow Tech data into the EE screening (completed in Sep 2023)
  3. Prototype (and possibly deploy) an integration of meteorological variables and air mass transform direction into the EE screening
  4. Prototype (and possibly deploy) an identification algorithm for similar meteorological days as to the smoke-influenced screened days using a Classification & Regression Analysis Tree (CART) analysis
  5. Conduct exploratory analysis for PM2.5 EE screening metric development: tracking daily total PM2.5 against the PM2.5 annual and 24-hour standards; determining indicator variables and anomaly values for identifying the potential smoke influence on PM2.5 concentration

2023 EE Screening Results (data retrieval on Sep 29, 2023)


2022 Analysis and Call Notes

Objectives of the 2022 EE workgroup:

  • Update the LADCO O3-PM2.5-CO anomaly metric to use a 5-year rolling average rather than a fixed period average. For example, 2021 EE data was normalized by monthly mean and standard deviation recorded in 2017-2021 period.
  • Prototype (and possibly deploy) a machine learning algorithm for smoke impact screening

2022 EE Screening Results (as of Sep 29, 2022)


2021 Analysis and Call Notes

Objectives of the 2021 EE workgroup:

  • Integrate metrics developed during the 2020 Chicago/W Michigan/Cincinnati EE project for identifying smoke impacts into our suite of EE screening products
  • Update the LADCO O3-PM2.5-CO anomaly metric to use a 5-year rolling average rather than a fixed period average. For example, 2021 EE data was normalized by monthly mean and standard deviation recorded in 2016-2020 period.
  • Prototype (and possibly deploy) a machine learning algorithm for smoke impact screening
  • Catalog all data that we’re using for EE screening and that are useful in an EE demonstration and come up with a plan to download and archive ephemeral data during potential smoke events before they’re deleted
  • Connect state air quality forecasters in the region with the EE workgroup such that we get notifications when there are smoke events impacting the region

2021 EE Screening Results (as of Oct 27, 2021)

2021 Call Notes


2020 Analysis and Call Notes

Objectives of the 2020 EE workgroup:

  • Identify potential EEs for ozone and PM2.5 in 2020
  • Review the 2018-19 records and find potential for regulatory significant EE events
  • Learn how to integrate other data, including satellite data into EE screening
  • Build a conceptual model for a regional EE demo

2020 EE Screening Results (as of Nov 20, 2020)

These plots will be updated through the season in advance of the monthly calls.  Note that ozone doesn’t appear on these plots until one of the monitors in the screening area violates the 2015 NAAQS (>70 ppb).

2020 Call Notes

Click to expand/collapse the call notes below


2019 Analysis and Call Notes

Objectives of the 2019 EE workgroup:

  • Identify potential EEs for ozone and PM2.5
  • Refine the screening metric
  • Learn how to integrate other data, including satellite data into EE screening
  • Learn from other areas/states that have conducted EE demonstrations

2019 EE Screening Results (as of October 3, 2019)

These plots will be updated through the season in advance of the monthly calls.  Note that ozone doesn’t appear on these plots until one of the monitors in the screening area violates the 2015 NAAQS (>70 ppb).

2019 Call Notes

Click to expand/collapse the call notes below


2018 Analysis and Call Notes

Summary: LADCO, the LADCO member states, and EPA R5 held monthly calls starting in August 2018 to review air quality data in the context of identifying potential exceptional events for ozone in the region.  Over the course of the ozone season, LADCO, in consultation with the regional EE workgroup, developed a screening metric using readily available monitoring data to identify EE potential in the region.  The final 2018 screening results, call notes, and presentations are included below.

2018 EE Screening Results

2018 Call Notes

Click to expand/collapse the call notes below