Name of the Subsidiary

State or Other Jurisdiction of Incorporation or Organization

Advanced GeoServices Corp.

Pennsylvania

Analytical Environmental Services

California

CTEH Government Services, LLC

Arkansas

CTEH IT Services, LLC

Arkansas

CTEH Leasing, L.L.C.

Arkansas

CTEH Properties, L.L.C.

Arkansas

Emerging Compounds Treatment Technologies, Inc.

Massachusetts

Enthalpy Analytical, LLC

Delaware

Environmental Alliance, Inc.

Delaware

Environmental Intelligence, LLC

California

Environmental Planning Specialists, Inc.

Georgia

Environmental Standards, Inc.

Pennsylvania

Epic Environmental Pty Ltd

Australia

ES Engineering Services, LLC

Delaware

FRS Environmental Remediation, Inc.

Florida

Horizon Water and Environment, LLC

California

Huco Consulting, Inc.

Texas

Leymaster Environmental Consulting, LLC

California

Montrose Air Quality Services, LLC

Delaware

Montrose Environmental Group AB

Sweden

Montrose Environmental Group GmbH

Germany

Montrose Environmental Group Ltd.

British Columbia

Montrose Environmental Group BV

Belgium

Montrose Environmental Group Denmark ApS

Denmark

Montrose Environmental Solutions Canada Inc.

Alberta

Montrose Environmental Solutions, Inc.

Delaware

Montrose Foreign Holdings, Inc.

Delaware

Montrose Government Solutions, Inc.

Delaware

Montrose Measurements and Analytics, LLC

Delaware

Montrose Planning & Permitting, LLC

Delaware

Montrose Services, LLC

Delaware

Montrose Waste-To-Resources, LLC

Delaware

Montrose Water and Sustainability Services, Inc.

Delaware

MSE Group, LLC

Texas

PARS Environmental, Inc.

New Jersey

SensibleIOT, LLC

California

Spirit Environmental, LLC

Texas

Sustainable Treatment Solutions, Inc.

New York

The Center for Toxicology and Environmental Health, L.L.C.

Arkansas

TriAD Environmental Consultants, Inc.

Tennessee

Two Dot Consulting, LLC

Colorado