Regulatory Compliance Matrix¶

pyaermod configurations vs. common regulatory guidance. Use this as a checklist when building a modeling protocol — the profile API (pyaermod.regulatory) automates most of these.

EPA Appendix W (40 CFR 51, 2017 revision)¶

Requirement	pyaermod setting
DFAULT option in MODELOPT	`ControlPathway.regulatory_default=True`
Elevated terrain	`ControlPathway.terrain_type = TerrainType.ELEVATED`
Rural/urban dispersion	`ControlPathway.urban_option` per source if urban
LOWWIND	only `LOWWIND3` is currently accepted with documentation
NO2 chemistry	OLM or PVMRM (set via `ChemistryOptions`) — GRSM and PVMRM2 remain BETA through 2023
Stack-tip downwash	on by default; don't set `no_stack_tip_downwash`
BETA / experimental options	not permitted under DFAULT

Apply with:

from pyaermod import EPA_APPENDIX_W_2017
changes = EPA_APPENDIX_W_2017.apply(project)
warnings = EPA_APPENDIX_W_2017.check(project)

EPA Appendix W (2023 updates)¶

Same base constraints as 2017. Two new NO2 chemistry methods (PVMRM2, GRSM) are available in AERMOD v23132/v24142 but remain BETA — they require case-by-case EPA concurrence before use in a regulatory submittal. EPA_APPENDIX_W_2023 therefore keeps only OLM and PVMRM in its allow_chemistry_methods tuple; the BETA set is listed separately in EPA_APPENDIX_W_2023_BETA_METHODS for users with explicit approval.

Other 2023 updates:

ADJ_U* friction-velocity adjustment is permitted for stable conditions with agency review.

Use EPA_APPENDIX_W_2023 for this profile.

Screening-level analyses¶

For scoping runs before a full regulatory submittal:

from pyaermod import SCREENING_PROFILE
SCREENING_PROFILE.apply(project)

Screening profile forbids all non-default options, including LOWWIND3. Tighten to a formal profile before submittal.

Per-state/agency notes¶

pyaermod doesn't currently ship state-specific profiles. Build your own by subclassing RegulatoryProfile:

from pyaermod import RegulatoryProfile

CARB_DRAFT_2024 = RegulatoryProfile(
    name="CARB-Draft-2024",
    description="California draft 2024 modeling guidance",
    regulatory_default=True,
    terrain_type="ELEVATED",
    allowed_low_wind=("LOWWIND3",),
    allow_chemistry_methods=("OLM", "PVMRM", "PVMRM2", "GRSM"),  # BETA incl.
    forbid_nondefault_flags=(
        "flat_terrain", "no_stack_tip_downwash",
        "use_lowwind1", "use_lowwind2",
    ),
)

Non-regulatory uses¶

For research or sensitivity work where DFAULT is not required, set regulatory_default=False explicitly — advanced_validate will then allow non-default options without flagging them.

What pyaermod does NOT verify¶

Site representativeness of met data. No automated check for distance, land cover similarity, or seasonal coverage.
Receptor placement relative to property boundaries / ambient air definitions.
Emission rates vs. permit limits. Presence is checked; values are not.
Background concentration source selection. Required set but not validated against monitor data.

These are policy / protocol questions your agency contact — not a Python library — has to answer.