What is one way to identify a lead hazard in plumbing systems?

Identifying a lead hazard in plumbing systems through visual inspection of pipes is effective because it allows operators to directly observe the materials used in the plumbing. Many older plumbing systems were installed with lead pipes, lead solder on joints, or other lead-containing fixtures. By visually inspecting the plumbing, operators can identify these materials and determine if a lead hazard is present.

In contrast, the other methods listed are less effective for identifying lead hazards specifically within plumbing systems. For instance, a standard thermometer is used to measure temperature, which does not provide any information regarding the materials present in the pipes. Conducting physical examinations typically refers to assessing health issues rather than inspecting materials in plumbing. Monitoring air quality may indicate the presence of lead in the air, but it does not directly assess the plumbing system itself for lead hazards. Thus, visual inspection remains the most straightforward and effective method for identifying lead in plumbing systems.