Passive samplers are devices used to collect environmental samples without the need for active pumping or mechanical systems. They rely on the natural movement of air or water to capture pollutants or chemicals over time. This method is often used in monitoring air quality, water quality, and soil contamination. These samplers are typically simple to deploy and can provide valuable data on the concentration of specific substances. They are particularly useful for long-term studies, as they can continuously collect samples without requiring constant attention or power sources, making them cost-effective and efficient for environmental assessments.