Which of the following is not a maintenance-related item contributing to dryer fires?

Air quality control is not a maintenance-related item contributing to dryer fires. While air quality is important in many aspects of safety and health in various environments, it does not directly relate to the maintenance of a dryer. In the context of dryer fires, key factors include the condition of the dryer drum, the need for regular and thorough maintenance and cleaning, and ensuring that components like drum wipers are not leaking or malfunctioning. These factors are critical in preventing lint buildup and ensuring that the dryer operates safely and efficiently, thereby reducing the risk of fire. The other choices focus explicitly on the physical condition and maintenance practices of the dryer, which are crucial for fire prevention.