Exhibit 99.1 MONTROSE ENVIRONMENTAL GROUP ANNOUNCES FIRST QUARTER 2024 RESULTS - Record First Quarter Revenue of $155.3 Million, up 18% Year-Over-Year - - Net Loss of $13.4 million; Basic and Diluted Net Loss Per Share of $0.53 - - Record First Quarter Consolidated Adjusted EBITDA1 of $16.9 Million - - Executed Three Highly Accretive Acquisitions and Expanded Patent Portfolio - - Reiterates Recently Raised 2024 Revenue and Consolidated Adjusted EBITDA1 Guidance - Little Rock, Arkansas (May 7, 2024) – Montro ...