Last week, a Maryland circuit court ruled that the state must regulate and limit ammonia pollution from industrial poultry operations. This landmark decision takes an important step toward protecting the environment and public health in the Old Line State and could spur similar action in other states.

It is certainly needed in Maryland. The state's Lower Eastern Shore is home to a large number of industrial poultry operations; three Lower Eastern Shore counties house close to 44 million chickens at any given time — roughly 241 times greater than the number of people in the region.

Every year, these operations release millions of pounds of ammonia — a form of nitrogen — into the environment, polluting our land, water, and air. Ammonia is a colorless compound formed when nitrogen in chicken manure breaks down. It enters the air as a gas and can land on the ground, polluting groundwater and nearby waterways.

Exposure to airborne ammonia contributes to poor health in nearby communities. Ammonia is water soluble and, when inhaled, quickly dissolves in the upper respiratory tract, irritating the eyes, nose, and throat. It also has a strong, unpleasant odor. In residential communities near industrial livestock operations, airborne ammonia concentrations are positively correlated …