Clean Harbors Names Andrea Robertson to Board of Directors.

Business Editors

BRAINTREE, Mass.--(BUSINESS WIRE)--June 15, 2004

Company Reaffirms Second-Quarter 2004 Financial Guidance;

Expects to Achieve Middle to Upper Levels of EBITDA Range

Clean Harbors, Inc. ("Clean Harbors") (Nasdaq: CLHB), the leading provider of hazardous waste and environmental management services throughout North America, today named Andrea Robertson, 47, as a new member on its Board of Directors. With the appointment, the Company now has nine directors, eight of whom are independent. Robertson will serve on the Board's Audit Committee.

"I am pleased to welcome Andrea to the Board," said Alan S. McKim, chairman and chief executive officer. "Her background in finance as a Certified Public Accountant and practical experience as both an auditor and financial executive with several multi-billion-dollar corporations will be invaluable to Clean Harbors going forward."

Ms. Robertson is currently Senior Vice President, Treasurer of MasterCard International. Prior to joining MasterCard, she held financial management positions with RR Donnelley and IBM, and served as an auditor with Coopers & Lybrand. Ms. Robertson received her B.S. in Accounting from Merrimack College and an MBA in Finance/Management Information Systems from the University of Chicago.

Guidance Update

Clean Harbors also announced that it is updating its EBITDA (Earnings Before Interest, Taxes, Depreciation and Amortization) guidance of $16 million to $19 million for the second quarter ending June 30, 2004. The Company now expects to be in the middle to top half of this range. The Company reaffirmed its second-quarter revenue guidance and continues to anticipate a sequential increase of between seven and 12 percent from the first quarter of 2004.

"At this point in the second quarter, we are clearly seeing the seasonal strength we cited as a key potential catalyst for growth," said McKim. "We expect this growth, along with continued execution of our cost reduction initiatives, to favorably influence Clean Harbors' EBITDA during the quarter."

Clean Harbors reports EBITDA results, which are non-GAAP, as a complement to results provided in accordance with accounting principles generally accepted in the United States (GAAP), and believes that such information provides investors with an additional tool for measuring the Company's performance. Clean Harbors defines EBITDA in accordance with its outstanding loan agreements.

About Clean Harbors, Inc.

Clean Harbors, Inc. through its subsidiaries provides a wide range of environmental and waste management services to a diversified customer base including a majority of the Fortune 500 companies, thousands of smaller private entities and numerous governmental agencies. Within its international footprint, Clean Harbors has service and sales offices located in 36 states, six Canadian provinces, Mexico, and Puerto Rico, and operates 52 waste management facilities strategically located throughout North America. For more information, visit our Web site at www.cleanharbors.com.

Safe Harbor Statement

Any statements contained herein that are not historical facts are forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, and involve risks and uncertainties. These forward-looking statements are generally identifiable by use of the words "believes," "expects," "intends," "anticipates," "plans to," "estimates," "projects," or similar expressions. These forward-looking statements are subject to certain risks and uncertainties that could cause actual results to differ materially from those reflected in these forward-looking statements. Readers are cautioned not to place undue reliance on these forward-looking statements, which reflect management's opinions only as of the date hereof. The Company undertakes no obligation to revise or publicly release the results of any revision to these forward-looking statements.

A variety of factors beyond the control of the Company affect the Company's performance, including, but not limited to:

-- The effects of general economic conditions in the United

States, Canada and other territories and countries where the

Company does business;

-- The effect of economic forces and competition in specific

marketplaces where the Company competes;

-- The possible impact of new regulations or laws pertaining to

all activities of the Company's operations;

-- The outcome of litigation or threatened litigation or

regulatory actions;

-- The effect of commodity pricing on overall revenues and

profitability;

-- The effects of the embedded derivative of the Company's

preferred stock on earnings per share;

-- Possible fluctuations in quarterly or annual results or

adverse impacts on the Company's results caused by the

adoption of new accounting standards or interpretations or

regulatory rules and regulations;

-- The effect of weather conditions or other aspects of the

forces of nature on field or facility operations;

-- The effects of industry trends in the environmental services

and waste handling marketplace;

-- The effects of conditions in the financial services industry

on the availability of capital and financing;

-- The Company's ability to successfully complete the integration

of the CSD acquisition which became effective in September

2002 and to manage the significant environmental liabilities

which it assumed in connection with that acquisition;

-- The availability and costs of liability insurance and

financial assurances required by governmental entities

relating to our facilities.

Any of the above factors and numerous others not listed nor foreseen may adversely impact the Company's financial performance. Additional information on the potential factors that could affect the Company's actual results of operations is included in its filings with the Securities and Exchange Commission, including but not limited to its Annual Report on Form 10-K, in its entirety and specifically Item 7, for the fiscal year ended December 31, 2003, and its Form 10-Q for the quarter ended March 31, 2004.