# 2021 NEI Modeling Platform: Could the generated 2021 emissions be affected by the lockdown policy in 2020?

**URL:** <https://forum.cmascenter.org/t/2021-nei-modeling-platform-could-the-generated-2021-emissions-be-affected-by-the-lockdown-policy-in-2020/5694>\
**Category:** NEI Modeling Platform\
**Tags:** smoke, emissions\
**Created:** [March 28, 2025, 3:39pm UTC](https://forum.cmascenter.org/t/2021-nei-modeling-platform-could-the-generated-2021-emissions-be-affected-by-the-lockdown-policy-in-2020/5694 "2025-03-28T15:39:54Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Huazhen](https://avatars.discourse-cdn.com/v4/letter/h/59ef9b/32.png) [@Huazhen](https://forum.cmascenter.org/u/Huazhen)\
**Post date:** [March 28, 2025, 3:39pm UTC](https://forum.cmascenter.org/t/2021-nei-modeling-platform-could-the-generated-2021-emissions-be-affected-by-the-lockdown-policy-in-2020/5694/1 "2025-03-28T15:39:54Z")

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Hi all,

The 2021 emissions are generated based on 2020 NEI. Some sectors’ emissions are projected or interpolated from 2020 NEI. However, there was lockdown policy in 2020 due to COVID19. I’m wondering if the generated emissions in some sectors in 2021 may be lower than the real emissions.

Thanks,  
Huazhen

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**Author:** ![eyth.alison](https://avatars.discourse-cdn.com/v4/letter/e/7ab992/32.png) [@eyth.alison](https://forum.cmascenter.org/u/eyth.alison)\
**Post date:** [March 31, 2025, 12:10pm UTC](https://forum.cmascenter.org/t/2021-nei-modeling-platform-could-the-generated-2021-emissions-be-affected-by-the-lockdown-policy-in-2020/5694/2 "2025-03-31T12:10:35Z")

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We computed the 2021 onroad activity data using available data from that year, so those emissions should not be underestimated.

Nonpoint sectors used activity inputs that were not impacted by COVID.

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**Author:** ![Huazhen](https://avatars.discourse-cdn.com/v4/letter/h/59ef9b/32.png) [@Huazhen](https://forum.cmascenter.org/u/Huazhen)\
**Post date:** [March 31, 2025, 1:50pm UTC](https://forum.cmascenter.org/t/2021-nei-modeling-platform-could-the-generated-2021-emissions-be-affected-by-the-lockdown-policy-in-2020/5694/3 "2025-03-31T13:50:43Z")

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Thanks a lot for the clarification.

Huazhen