About Us

CHESTER LabNet (CLN) is a small laboratory that specializes in inorganic air quality analysis. Our staff is dedicated to the satisfaction of our clients, and responsive to the unique needs of the air quality industry. CLN has a great depth of knowledge of inorganic air quality methods and their nuances.

CLN was originally founded in 1977 as NEA, Inc. In 1991, the laboratory was sold to Chester Environmental and became part of the Chester LabNet laboratory network. CLN was later purchased by private investors and has been independent since 1994.

Key Personnel

Paul Duda

Paul Duda – President, Laboratory Director, Client Services Technical Director, Lead Project Manager

Email: pduda@chesterlab.net

Hire Date: December 1989

Education: B.S. Engineering Management, University of Portland

Background: Gravimetric lab technician, XRF analyst, project manager, and LIMS administrator; promoted to President in 2001. Currently a member of the Air and Waste Management Association (A&WMA) and Source Evaluation Society (SES). Received PNWIS-A&WMA Lab Coat Award in 2012


Lisa Ball

Lisa Ball – Project Manager, Sample Custodian

Email: lball@chesterlab.net

Hire Date: October 1997

Education: B.S. Integrated Science, Portland State University

Background: Environmental analyses of air, soil and water samples; project manager and sample custodian.


Mike May

Mike May – QA Officer, Conventional Chemistry Technical Director, Lead Analyst

Email: mmay@chesterlab.net

Hire Date: August 2008 – November 2011, November 2017 – Present

Education: B.S., Biology, Portland State University

Background:  Analysis of environmental and production samples.  Quality Control/Quality Assurance including EPA CLP and NELAP. Currently a member of The NELAC Institute (TNI).


Richard Sarver

Richard Sarver – XRF Technical Director

Email: rsarver@chesterlab.net

Hire Date: November 1986

Education: A.A.S. Chemical Technology, Chemeketa Community College

Background: Source Sampling, XRF analyst.


Ted Perry – Gravimetric Laboratory Technical Director, XRF Analyst

Email: tperry@chesterlab.net

Hire Date: September 2015

B.S., Chemistry (Environmental Chemistry option), Oregon State University

Background: Environmental analyses of air, soil and water samples; Gravimetric Laboratory Technical Director.


Employee Hall of Fame

Sheri Heldstab

Sheri Heldstab – retired QA Officer and Conventional Chemistry Technical Director

Email: SheriLHeldstab@gmail.com

Retired: April 2022

Education: B.S. Biology, University of Oregon

Career Highlights:  Sheri worked for CLN for 28 years where she ran the conventional chemistry lab and served as QA Officer. One of her biggest accomplishments was co-authoring the ASTM method (D7614-20) for hexavalent chromium in ambient air. Towards the end of her tenure at CLN, she was the Chair of the TNI SSAS Expert Committee and was the Editor of The Platform, the Source Evaluation Society’s quarterly newsletter. Sheri may not be working with us anymore but her legacy will will be felt for years to come.

Publications and Presentations:

ASTM D7614-20

Cr VI Paper presented at NEMC

PowerPoint for Cr VI presentation

PowerPoint for Source Emission Uncertainty presentation

The Laboratory: A Peek Inside the Black Box presentation

CARB 436: A Cautionary Tale of Methods, Math and Miscalculations


Photography: Human Nature Art