The percentage of residuals (unrecoverable recyclable or non-program materials) from a properly operated clean MRF supported by an effective public outreach and education program should not exceed 10% by weight of the total delivered stream and in many cases it can be significantly below 5%. A dirty MRF recovers between 5% and 45% of the incoming material as recyclables, then the remainder is landfilled or otherwise disposed. A dirty MRF can be capable of higher recovery rates than a clean MRF, since it ensures that 100% of the waste stream is subjected to the sorting process, and can target a greater number of materials for recovery than can usually be accommodated by sorting at the source. However, the dirty MRF process results in greater contamination of recyclables, especially of paper. Furthermore, a facility that accepts mixed solid waste is usually more challenging and more expensive to site. Operational costs can be higher because it is more labor-intensive.