Answer: Carbon dioxide (CO₂) would be most of the tons reduced from the lack of motor vehicles in the park during the park shutdown because of the pandemic.  Carbon monoxide (CO), nitrogen oxides (NO_x),  volatile organic compounds (VOCs), and particulate matter are other emissions that were lower, but to a much lesser extent.  

HP: During what time frame?

A: It was based on when the primary park roads were closed, for about a six-week period from March 24 through May 9 (2020) 

HP: Was this based on data collected at the Look Rock air-quality monitoring station or monitoring sites throughout the park? 

A: No, it was estimated reductions in air emissions (tons) from using the park's emissions inventory for criteria air pollutants and greenhouse gases coupled with the reduction in park visitation data for the period of the park shutdown.

HP: Was this a result of reduced auto travel in the park? 

A: Yes. 

HP: A lot of emissions, of course, come from outside of the park. Was the improvement in air quality also a function of reduced pollutants coming from outside the park? 

A: The documented reduction was with emissions, not air quality. Air quality analysis is still under way to look at changes in air pollutants. 

HP: What do you think the primary reasons for the air quality improvements were?  

A: If there were reductions in air pollutants (and that is still being analyzed by EPA and NPS Air Resources Division), it was due primarily to the reduction in motor vehicle emissions in and near the park (and regionally).

HP: Did you purposefully set out to quantify the pandemic’s effect on air quality, or was this an “accidental” discovery? 

A: We did not purposefully set out to quantify the pandemic's effect on air quality. Monitoring efforts continued during the pandemic and provided a unique and unexpected opportunity to characterize the differences in air emissions (from park closures and limited motor vehicle emissions) and air pollutants (which will take longer to look at laboratory analysis after quality assured analysis).

HP: How is this a positive for the Smokies and park visitors?

A: It allows us to look at the changes in emissions and air quality from the reduction in visitation and motor vehicle emissions. 

HP: Have you ever seen a period of such drastic reduced pollutants in the park?   

A: No. There have been times when the park is closed due to inclement weather, but that usually only lasts a few days at most. The park closure was about six weeks. 

HP: Was this a truly unique period for research, and how can that baseline be used moving forward?  

A: I think we look at differences in emissions and air quality during this same time period in other years that didn't experience a pandemic and compare those to look at key differences, both in the monitoring and the modeling of air quality.

HP: Visitation was very high when the park reopened. Were those air quality gains quickly reversed, or did the park enjoy better air quality through the past year?  

A: Air quality continues to improve here at GRSM over the past 20 years. Much of the recent monitoring data that was collected during 2020 is still going through QA/QC procedures in the labs before it is ready to share.  So, too early to tell.

HP: What are the air quality trends over the past 10 years? Improvements or backsliding? 

A: Air quality has continued to improve over the past 10 years for ozone, particulate matter, acid deposition, and regional haze.

HP: What are the main reasons for air quality improvements during that period?  

A: Continued emission reductions of sulfur dioxide (improves visibility, acid deposition and particulate matter) from power plants and lower nitrogen oxides (improves ground level ozone, acid deposition, particulate matter, and regional haze) from power plants and motor vehicles.

HP: Have you yet better parsed the data to get a fuller look at how the 2020 improvements might affect “downstream” natural attributes of the park such as acid deposition or mercury contamination? 

A: No. Final QA/QC'd data is not available for much of the 2020 air quality data.  

HP: Will this period of reduced emissions have a positive effect on other park resources?  

A: Most of the emission reductions were short-term reductions during the shutdown period. Once the full and final data is available, it will be easier to evaluate the changes in seasonal and annual air pollutants.

HP: What is your projection for park air quality over the next 10 years? 

A: I know from some of the regional haze forecasted modeling projecting out to the year 2028, conducted by the states under the Regional Haze Rule, there will be additional emission reductions of SO₂ and NO_x, resulting in less regional haze, improved visibility, and lower acid deposition.

HP: What needs to be done to ensure improvements occur, or continue? Are there any new threats, or is it the same list of usual pollutant suspects from over the years? 

A: The NPS continues to work with states, EPA and the public to monitor air pollutants in order to maintain air quality standards and protect ecosystems. Acid deposition, regional haze, ozone, particulate matter, and mercury bioaccumulation are still air pollution concerns here at the park.