Senate Bill No. 356, introduced by Senator Duplessis, aims to enhance air quality monitoring by requiring certain facilities that emit toxic air pollutants to install and operate air monitoring systems along their perimeters. The bill defines "facility" as those classified under the North American Industry Classification Code System as petroleum refineries or chemical manufacturing facilities with annual emissions exceeding 50 pounds of any of the specified toxic air pollutants. It establishes definitions for "toxic air pollutant" and "acute exposure thresholds" for various airborne chemicals, and mandates that facilities monitor these pollutants and alert interested parties when concentrations exceed set thresholds.

The proposed law outlines specific requirements for the air monitoring systems, including planning, design, equipment, installation, data collection, public notification, and reporting. Facility owners are responsible for all costs associated with the air monitoring systems, and they must submit an "air monitoring system plan" to the Department of Environmental Quality (DEQ) prior to installation. This plan must include an inventory of equipment, quality control protocols, and maintenance schedules. Additionally, facilities are required to maintain real-time and historical data on pollutant measurements and provide quarterly reports to the DEQ. The bill also authorizes the DEQ to adopt necessary rules for implementation, with an effective date of August 1, 2026.