How to Improve the Disinfection Effect of Air Conditioning Filter Screens in Operating Rooms？

The air conditioner in an operating room is a source of air pollution, and it is necessary to regularly clean or disinfect the air conditioner filters to control the air pollution source. In the past, the air conditioner filters in our hospital's operating rooms were mostly cleaned using the method of flowing water scrubbing, which could not effectively control the bacterial count, resulting in a low hygiene qualification rate. To improve the cleaning and disinfection effectiveness of air conditioner filters, we adopted a method of scrubbing followed by disinfectant spray using a long-chain quaternary ammonium salt, and achieved good results. The disinfectant used contained 1000 mg/L of long-chain quaternary ammonium salt, and its actual disinfection effect was tested. The results are reported as follows:

1. Method:
Sixty air conditioner filters were selected and divided into an experimental group and a control group, with 30 filters in each group. Before cleaning and disinfection, sterile cotton swabs were used to sample the area of 5cm×5cm on the air conditioner filters by uniformly wiping back and forth 5 times with sampling fluid. This served as the positive control before disinfection. In the experimental group, the air conditioner filters were first cleaned with flowing water, and then dried with sterile wipes. On this basis, the filters were then sprayed with a disinfectant containing 1000 mg/L of long-chain quaternary ammonium salt for 3-5 minutes before sampling. In the control group, the filters were cleaned with flowing water, dried with sterile wipes, and immediately sampled after cleaning. The sampling method was the same as the pre-disinfection sampling. The sterile cotton swab heads used for sampling were cut into test tubes containing 10 ml of sterile elution solution with the corresponding neutralizer, thoroughly shaken for elution, and the elution solution was used for viable bacterial count culture to calculate the total number of viable bacteria.

The evaluation criteria for the results were based on the standard GB15982-1995 "Hygienic Standard for Hospital Disinfection." Qualified results were defined as having a total bacterial count of no more than 5 colonies/cm2 on the surface of objects in Class II areas, and the absence of pathogenic bacteria.

2. Results:
The results of the tests showed that after the filters in the experimental group were cleaned with flowing water and then sprayed with the disinfectant containing 1000 mg/L of benzalkonium chloride and chlorhexidine, the total bacterial count on the surface of the air conditioner filters was reduced to <1.0 cfu/cm2 after a 5-minute action time. The disinfection qualification rate was 100%. In the control group, although cleaning the air conditioner filters with water alone reduced the number of contaminated bacteria to some extent, the hygiene qualification rate was only 30%.

Comparison of two methods for cleaning and disinfecting air conditioning filter screens:

Therefore, we believe that the approach of regular cleaning followed by disinfectant spray using long-chain quaternary ammonium salt can meet the hygiene quality requirements for air conditioner filters in operating rooms. It is recommended to clean and disinfect them once a week and enhance the cleanliness and hygiene management during the use of the air conditioner to prevent an elevation of indoor microbial counts.