Any waste management facility, including a composting site, has the potential to generate offensive odors or attract pests. However, experience at hundreds of composting facilities has shown that proper design and operational procedures can prevent or control these problems. Excessive or offensive odors are generally a sign that the composting process is not proceeding properly, usually because of inadequate aeration or excessive moisture. Close monitoring of these factors can usually help to minimize odors. Facilities can employ abatement systems, such as biofilters, to treat occasional odors. Preventing odors and ensuring that the site is kept clean will ensure that the site does not attract rodents or other pests.