Company lists · Data refreshed September 2026

Top 25 Air quality engineering firms based in the United States

Name: Air quality engineering firms based in the United States
Creator: RevenueBase
License: https://creativecommons.org/licenses/by/4.0/

Compiled by the RevenueBase Data Team Data refreshed Sep 30, 2026 1,962 companies tracked

RevenueBase identified 1,962 air quality engineering firms headquartered in the United States as of September 2026 and tracks 36,764 professional contacts across them, including 17,243 with verified work emails. Houston is the largest hub.

This list covers air quality engineering firms headquartered in the United States, matched on what each company actually does as described in its own words. Ranked by team size, largest first. Every row shows the company's own description, its RevenueBase Smart Search rating, and when it was last checked. Data refreshed September 30, 2026.

Published by RevenueBase, a B2B data infrastructure company. This list was built with RevenueBase Smart Search, the natural-language company search RevenueBase customers use to build their own targeted lists and unlock verified emails and direct dials at the companies on them. How these lists are built and judged.

How to read this list HQ checked on every row RevenueBase Smart Search rating on every row Refreshed Sep 30, 2026 86% judged on-target in blind review

1,962Companies

36,764Contacts tracked

17,243Verified emails

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The 25 largest air quality engineering firms based in the United States

Ranked by team size

Top 25 of 1,962 air quality engineering firms based in the United States, ranked by team size, largest first. Data refreshed Sep 30, 2026. RevenueBase Smart Search rates how each company's information relates to air quality engineering firms: strong evidence (its own description names it), partial (names part of it), indirect (matched on the rest of its profile rather than the description shown). Click a contact count to view that company's people.
#	Company	RevenueBase Smart Search	Headquarters	Employees	Contacts
1	Civil & Environmental Consultants, INC	Indirect evidence	Moon Township, PA, United StatesHQ checked Sep 30, 2026	1,001-5,000	2,145 contacts →
	Indirect evidence “Civil & Environmental Consultants, Inc.(CEC) provides comprehensive market-oriented consulting services that advance the strategic business objectives of its clients.” Source: RevenueBase Database · checked Sep 30, 2026
2	Swca Environmental Consultants	Indirect evidence	Phoenix, AZ, United StatesHQ checked Sep 30, 2026	1,001-5,000	1,629 contacts →
	Indirect evidence “Founded on a commitment to sound science and creative solutions, SWCA is a leader in environmental and management consulting services.” Source: RevenueBase Database · checked Sep 30, 2026
3	Barr Engineering CO	Partial evidence	Minneapolis, MN, United StatesHQ checked Sep 30, 2026	1,001-5,000	1,088 contacts →
	Partial evidence “Barr provides engineering and environmental consulting services to clients across the Midwest, throughout the Americas, and around the world.” Source: RevenueBase Database · checked Sep 30, 2026
4	Trinity Consultants	Indirect evidence	Dallas, TX, United StatesHQ checked Sep 30, 2026	1,001-5,000	961 contacts →
	Indirect evidence “Trinity Consultants is a global team of experts helping organizations solve complex challenges in environmental compliance, ecological protection, infrastructure performance, and…” Source: RevenueBase Database · checked Sep 30, 2026
5	Alliance Technical Group	Indirect evidence	Decatur, AL, United StatesHQ checked Sep 30, 2026	1,001-5,000	956 contacts →
	Indirect evidence “Alliance is a new kind of environmental services company-powered by innovation, focused on service, and committed to client success.” Source: RevenueBase Database · checked Sep 30, 2026
6	ATC Group Services LLC	Indirect evidence	Lafayette, LA, United StatesHQ checked Sep 30, 2026	1,001-5,000	865 contacts →
	Indirect evidence “ATC Group Services LLC is now Atlas.” Source: RevenueBase Database · checked Sep 30, 2026
7	AAF International American AIR Filter	Partial evidence	Louisville, KY, United StatesHQ checked Sep 30, 2026	1,001-5,000	806 contacts →
	Partial evidence “AAF International clean air products and systems offer the most comprehensive clean air solutions available in the world.” Source: RevenueBase Database · checked Sep 30, 2026
8	Antea Group USA	Partial evidence	St. Paul, MN, United StatesHQ checked Sep 30, 2026	1,001-5,000	658 contacts →
	Partial evidence “Antea Group is an international engineering and environmental consulting firm specializing in full-service solutions in the fields of environment, health and safety, and…” Source: RevenueBase Database · checked Sep 30, 2026
9	Trihydro Corporation	Strong evidence	Laramie, WY, United StatesHQ checked Sep 30, 2026	501-1,000	577 contacts →
	Strong evidence “Headquartered in Laramie, Wyoming, Trihydro provides environmental consulting, engineering and surveying, air quality and process management, information technology, and water and…” Source: RevenueBase Database · checked Sep 30, 2026
10	Rincon Consultants	Strong evidence	Ventura, CA, United StatesHQ checked Sep 30, 2026	501-1,000	479 contacts →
	Strong evidence “Rincon Consultants is a multi-disciplinary environmental sciences, planning, and engineering consulting firm that provides quality professional services to government and industry.” Source: RevenueBase Database · checked Sep 30, 2026
11	Groundwater & Environmental Services, INC	Indirect evidence	Wall Township, NJ, United StatesHQ checked Sep 30, 2026	201-500	447 contacts →
	Indirect evidence “We are Groundwater & Environmental Services, Inc, better known as GES.” Source: RevenueBase Database · checked Sep 30, 2026
12	ROUX	Indirect evidence	Islandia, NY, United StatesHQ checked Sep 30, 2026	201-500	433 contacts →
	Indirect evidence “Founded 40 years ago, Roux is recognized for being a highly effective, client-focused environmental consulting and management firm.” Source: RevenueBase Database · checked Sep 30, 2026
13	P2s	Partial evidence	Long Beach, CA, United StatesHQ checked Sep 30, 2026	201-500	375 contacts →
	Partial evidence “P2S has brought forward-thinking, sustainable engineering solutions to California, the Pacific Northwest, and beyond, for over 30 years.” Source: RevenueBase Database · checked Sep 30, 2026
14	All4	Indirect evidence	Kimberton, PA, United StatesHQ checked Sep 30, 2026	201-500	331 contacts →
	Indirect evidence “ALL4 is a global consulting firm committed to shaping a sustainable future through innovative environmental, health, and safety (EHS) and digital solutions.” Source: RevenueBase Database · checked Sep 30, 2026
15	Ecology And Environment, INC	Indirect evidence	Lancaster, NY, United StatesHQ checked Sep 30, 2026	5,001-10,000	278 contacts →
	Indirect evidence “E&E is now WSP USA.” Source: RevenueBase Database · checked Sep 30, 2026
16	GSI Environmental INC	Partial evidence	Houston, TX, United StatesHQ checked Sep 30, 2026	201-500	259 contacts →
	Partial evidence “GSI Environmental, Inc.(GSI), is an environmental engineering and science consulting firm committed to measuring, analyzing, and solving complex environmental problems around the…” Source: RevenueBase Database · checked Sep 30, 2026
17	Hyde Engineering Consulting	Partial evidence	Louisville, CO, United StatesHQ checked Sep 30, 2026	201-500	253 contacts →
	Partial evidence “Hyde E+C is an international engineering consulting firm that helps companies operate more efficiently, get products to market more quickly, meet regulatory requirements more…” Source: RevenueBase Database · checked Sep 30, 2026
18	Environmental Works, INC	Indirect evidence	Springfield, MO, United StatesHQ checked Sep 30, 2026	201-500	238 contacts →
	Indirect evidence “Environmental Works, Inc.(EWI) offers truly comprehensive environmental solutions for a variety of industries, businesses, and municipalities.” Source: RevenueBase Database · checked Sep 30, 2026
19	Hillmann Consulting, LLC	Indirect evidence	Union, NJ, United StatesHQ checked Sep 30, 2026	201-500	209 contacts →
	Indirect evidence “Hillmann has been a well-recognized leader in the Environmental Health & Safety, Due Diligence & Remediation Management, and Construction Services industries since 1985.” Source: RevenueBase Database · checked Sep 30, 2026
20	Normandeau Associates, INC	Indirect evidence	Bedford, NH, United StatesHQ checked Sep 30, 2026	201-500	189 contacts →
	Indirect evidence Source: RevenueBase Database · checked Sep 30, 2026
21	Thielsch Engineering	Indirect evidence	Cranston, RI, United StatesHQ checked Sep 30, 2026	501-1,000	175 contacts →
	Indirect evidence “Thielsch, Inc.” Source: RevenueBase Database · checked Sep 30, 2026
22	Forensic Analytical Consulting Services, INC	Indirect evidence	Hayward, CA, United StatesHQ checked Sep 30, 2026	51-200	172 contacts →
	Indirect evidence “With a staff of over 150 employees in the San Francisco, Sacramento, Los Angeles, San Diego, Modesto, Bakersfield, Fresno, Portland, Chicago, and Grand Rapids offices, Forensic…” Source: RevenueBase Database · checked Sep 30, 2026
23	Terraphase Engineering INC	Partial evidence	Oakland, CA, United StatesHQ checked Sep 30, 2026	201-500	166 contacts →
	Partial evidence “Terraphase offers cost-effective solutions to complex environmental and engineering challenges.” Source: RevenueBase Database · checked Sep 30, 2026
24	Ecorp Consulting, INC	Indirect evidence	Rocklin, CA, United StatesHQ checked Sep 30, 2026	51-200	166 contacts →
	Indirect evidence Source: RevenueBase Database · checked Sep 30, 2026
25	TASC	Indirect evidence	Seabrook, TX, United StatesHQ checked Sep 30, 2026	201-500	161 contacts →
	Indirect evidence “Automation and Technology Group: Specializing in Analyzer System Integration.” Source: RevenueBase Database · checked Sep 30, 2026

RevenueBase Smart Search

RevenueBase Smart Search assesses information from a company’s LinkedIn profile, information supplied directly by the company, its website, and other publicly available sources. It uses that information to rate how closely the company relates to this list’s category: air quality engineering firms. Every row carries its rating and the description the rating was read from, so each one can be checked rather than taken on trust.

Strong evidence: The company's own public description of its business names air quality engineering firms.
Partial evidence: Its own public description names part of air quality engineering firms, so it works in or next to the category without describing itself that way.
Indirect evidence: The description shown does not name air quality engineering firms. The match rests on the rest of the company's public profile rather than the one sentence quoted here, so this is the rating to check first.

RevenueBase Smart Search is how these lists are built: RevenueBase's data engine and AI assemble the companies that match a category defined in a user's own words, so a list can be about what companies actually do rather than about whichever industry code they were filed under.

Showing 25 of 1,962 air quality engineering firms based in the United States

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Air quality engineering firms based in the United States at a glance

As of Sep 30, 2026

46.9%Verified-email coverage

18.7Average contacts per company

1-10Median size (employees)

2.4%Largest-city concentration · Houston

Sep 30, 2026Page data refreshed

Companies by employee count

1-10

1,035

11-50

693

51-200

182

201-500

501-1,000

1,001-5,000

5,001-10,000

10001+

Email recency for this list is measured worldwide rather than for United States, so it is reported there. Company counts and contact totals on this page are exact for United States, over 1,962 companies.

How this list was built

Company categories are rarely black and white. RevenueBase reads each company's own description of its business to decide whether it belongs among air quality engineering firms, so some rows will be adjacent to the category rather than pure plays. The description and RevenueBase Smart Search rating on every row are there so you can check each match yourself.

Source: The RevenueBase company graph: 60 million companies and 398.9 million professional contacts resolved from primary sources, queried with RevenueBase Smart Search, the natural-language company search available to every RevenueBase user.
What qualifies: Companies headquartered in the United States whose own description of what they do matches “air quality engineering firms”. Matching reads each company's description, not its industry code or its name.
RevenueBase Smart Search: RevenueBase Smart Search is how this list is assembled and how each row is rated. RevenueBase's data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to a category defined in a user's own words. Each row is rated strong evidence (its own description names air quality engineering firms), partial evidence (it names part of the category) or indirect evidence (the description shown names none of it and the match rests on the rest of the company's profile). The description supporting each rating is quoted on the row.
What we exclude: Companies whose own description does not clearly place them among air quality engineering firms, and records with no verified work email. Companies headquartered outside United States are excluded even when they keep an office there.
Match quality: In blind human judging of this matching method, 86% of matched companies were on target. Expect roughly 1 in 7 rows to be adjacent to the category rather than a pure play. Every row shows the company's own description and its RevenueBase Smart Search rating so you can judge each match yourself. Read the full methodology: how the lists are built, how the judging worked, and what the figure means.
Ranking: Team size, largest first: companies are ordered by the number of professionals RevenueBase tracks at each one. Employee ranges shown are reported bands, for context.
Verification: Every listed company carries at least one verified work email, 17,243 across the full list. Contacts re-verify on a rolling cadence, and each contact's own verification date is shown inside RevenueBase.
Refresh: This page's figures were pulled from the company graph on September 30, 2026. Lists refresh periodically as the graph is re-checked.
Corrections: Wrong category, wrong headquarters, or a company that has closed? Use “Report an issue” on any row. Reports go to the RevenueBase Data Team and feed back into the company graph.

Air quality engineering firms by metro

Frequently asked

What is RevenueBase Smart Search?

RevenueBase Smart Search is how RevenueBase decides which companies belong on this list and how strongly each one fits. Its data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to the category the list is about. Each row is rated strong evidence when the company's own description names air quality engineering firms, partial evidence when it names part of the category, and indirect evidence when the description shown names none of it and the match rests on the rest of the company's profile.

How many air quality engineering firms are there based in the United States?

RevenueBase identified 1,962 air quality engineering firms headquartered in the United States as of September 2026, matched on each company's own description of what it does rather than its industry code.

What is the largest company on this list?

Civil & Environmental Consultants, INC, headquartered in Moon Township, tops this list with the largest team on record.

Which city has the most air quality engineering firms?

Houston leads with 48 headquartered companies, followed by New York (26) and Tampa (20).

How do I get contact information for these companies?

A free RevenueBase account lets you run this exact search and work the top results, verified emails and direct dials included. Upgrading unlocks all 17,243 verified decision-maker contacts tracked across these 1,962 companies.

How current is this list?

The list refreshes periodically as the company graph is re-checked. This page's figures were pulled on September 30, 2026.

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About this data

RevenueBase is a B2B data infrastructure company. Its company graph covers 60 million companies and 398.9 million professional contacts, with emails verified on a rolling cadence rather than scraped once and left to decay. These company lists are generated directly from that graph with RevenueBase Smart Search, the same natural-language company search every RevenueBase user has: describe a market in plain words, get the companies that match, and add verified emails and direct dials for the people at them. It is the same data that powers RevenueBase's B2B data products, and a free account includes 500 credits to start. How these lists are built and judged.