About
A business will achieve higher cost efficiency with outsourcing the cleaning and maintenance work compared to having it done in-house. This is because in addition to the purchase of equipment and materials, the company will have to invest in the professional training of in-house staff. If additional workers are hired, the cost will climb further up. Given that the care for air vents and shafts is not a daily or even weekly task for the majority of businesses, it is simply not economical to go for the in-house option.
Google