1. Hypochlorite Disinfectant (bleach)
2. Procedures and Safety Precautions in Diluting Hypochlorite Solution
3. Procedures for using Hypochlorite Solution
4. Disinfection of Filters in Ventilation System
5. Procedures for Cleaning and Disinfection of Computer Stations
6. Procedures for Disinfecting Offices and Office Equipment
7. Procedures for Disinfection of Hostel
8. Procedures for Cleaning and Disinfecting Rooms in Hostels
9. Procedures for Disinfection of Canteens
10. Procedures for Disinfection of Buses
11. Disinfection of Residence
12. Procedures for Disinfecting Lifts
13. Procedures for Disinfecting Garbage Collection Stations

  (1) Hypochlorite Disinfectant

Hypochlorite solution, commonly known as ‘bleaching solution’, is a very powerful disinfectant and are available at supermarkets.  Regular hypochlorite solution may contain up to 5.25% hypochlorite and concentrated solution has 6% of the active chemical.

As an alternate source, USEO has concentrated hypochlorite solution that can be provided to users for disinfection (contact no. 26097958). 

In areas with heavy human traffic, a working solution of 0.1% hypochlorite strength should be used for disinfection. 

For domestic uses, half of the above strength, that is, 0.05% hypochlorite solution should be adequate.

1. Remember:
1. Do not mix hypochlorite solution with acids or alkaline. 
2. Do not use hot water to dilute the chemical. 
3. Do not use hypochlorite in undiluted form.
4. Store concentrated hypochlorite solution in secure places and away from sunshine or source of heat.
5. Always ensure that the hypochlorite container has proper label.
6. Call USEO (phone no. 2609 7958) for advice if in doubt.
2. For your own protection:
1. Prepare hypochlorite solution in place with good ventilation.
2. Put on gloves, masks and eye protector.
3. Prepare only the volume of diluted solution you can handle for your work.
4. Wash with copious amount of water if your body has been in contact with hypochlorite solution
3. Select ventilated (such as under exhaust fans in bathrooms or kitchens) when diluting hypochlorite solutions
4. Put on gloves, masks and eye protector before handling hypochlorite solution.
5. Estimate the volume of working solution required and add the required volume of water into a plastic container.  One part of hypochlorite solution should be diluted with approximately 50 parts of water to result in working solution of 0.1% strength (for concentrated hypochlorite solution, the dilution should be approximately 1 part in 60 parts of water).  For example, if 5 liters of 0.1% hypochlorite solution is needed, pour 5 liters of water into the container and add in approximately 100 milliliter of 5.25% hypochlorite solution.
6. Wash with copious amount of water if the body is in contact with hypochlorite solution.

1. Use mops wetted with 0.1% hypochlorite solution to clean the floor.  All visible surfaces including furniture, window sills, doors and windows should be wiped with a cloth dampen with diluted hypochlorite solution.  After five to ten minutes, use another piece of cloth dampened with water to wipe the surfaces again.
2. Hypochlorite solution is for general cleaning/disinfection purpose.  Computers and electronic equipment should be cleaned using other agents (Section 5).
3. After cleaning, wait for the wet surfaces to dry completely before using the facilities again.

Filters in ventilation system should be cleaned at least once every week using disinfectants. 

Where hypochlorite solution is found not suitable for use with filters, tertiary ammonium compounds or other types of disinfectant should be used.

Keyboards and mouse of computer workstations, especially those intended for multiple users, should be cleaned and disinfected periodically.

1. Before cleaning, ensure that the computer and monitor are turned off.
2. Direct the suction nozzle of the vacuum cleaner across rows of keys on the keyboard to remove dirt/dust accumulated in between keys.  Hand brush may be used to assist in removing settled dirt/dust between punches.
3. Use cloth dampened with ethyl alcohol to wipe the keyboard and mouse. 
4. Wait till the alcohol has evaporated before returning the computer for normal usage.
5. Use 0.1% hypochlorite solution to wipe clean the surface of CPU and monitor casings.  Wait for 5 minutes and use another piece of cloth dampen with water to clean off residual hypochlorite.
6. The glass surface of video display terminals with cathode ray tubes may be cleaned and disinfected using diluted hypochlorite solution, and then with a cloth dampened with water.
7. The video display surface of LCD monitor should be wiped very gently using cloth dampened with water.  No chemical disinfectant should be used to clean the delicate surfaces of LCD monitors.

1. Floors with PVC floor tiles should be mopped using 0.1% hypochlorite solution. 
2. Floors with carpets should be vacuumed cleaned before carpet shampoo is used for further cleaning.
3. Work desks should be cleaned and disinfected using 0.1% hypochlorite solution and followed by cloth dampened with water.
4. Keyboards and mouse of the computer station should be cleaned periodically using ethyl alcohol while the CPU and monitor casing should be cleaned using 0.1% hypochlorite solution followed by water as described in Section 5(e) to 5(g) above.
5. Other office equipment such as photocopiers and laser printers should be cleaned following the procedures outlined in (6) (d).  

  (7)    Procedures for Disinfection of Hostel

1. Use 0.1% hypochlorite solution to mop the floor and a cloth dampened with disinfectant to clean surfaces in common areas such as corridors, pantry and bathrooms on a daily basis.
2. Resident’s room should be cleaned by the residents themselves using 0.05% hypochlorite solution.
3. Cooking utensils, cutlery and food containers should be washed and disinfected using hypochlorite solution and then rinsed with water.
4. All rubbish bins should be emptied daily and the contents properly disposed of.
5. Filters of window-mounted air conditioners should be taken out and washed to remove dust accumulated on it.  After washing, the filters should be dipped into 0.1% hypochlorite solution for 10 minutes, then rinse in water and dry. This should be done weekly
6. Prepare approximately 10 litres of 0.1% hypochlorite solution (200 millilitres of concentrated hypochlorite solution in 10 litres of water) in plastic buckets and flush down the toilet.  Do not use the toilet for the next fifteen minutes.
7. Prepare 1 litre of 0.1% hypochlorite solution (approximately 20 millilitres in 1 litre of water) and pour down the washing basin.  Do not use the washing basin for the next fifteen minutes.  Rinse off the residual disinfectant by turning on the water taps of the washing basin.  Similar procedures should be repeated for other drainage openings.     

(8)    Procedures for Cleaning and Disinfecting Rooms in Hostels

Students should clean their own room, as there may be problems in handling their personal belongings and properties by cleaners as well as difficulties in making arrangement for the service.

Most of the cleaning and disinfection works should follow the guidelines outlined above.  Cleaning tools and disinfectant can be obtained from the hostel cleaners

(8a)  Window-mounted Air Conditioner

1. Take the filter out and bring it to the cleaner’s basin in the washroom.  Turn on the water tap and wash off the accumulated dirt from the filter.  After washing, the remaining dirt should be removed from the sink and dumped properly.
2. Dip the filter in 0.1% hypochlorite solution for ten minutes.
3. Take the filter out and wash it again with water.  Put the filter aside for drying.
4. When the filter is thoroughly dried, put it back into the filter slot in the air conditioner.
5. The filter should be cleaned and disinfected on a weekly basis.

(8b)  Desks, Chairs, Wardrobe, Window Sill, Windows, Blinds, Bed Frames and Bookshelves  

1. Before cleaning, all items should be removed from the surfaces to be cleaned.
2. Use 0.1% hypochlorite solution to wipe clean the surface.  Wait until the disinfectant is dried up, and then repeat the process again using water.

(8c)  Computer Station

1. Before cleaning, ensure that the computer and monitor is turned off.
2. Direct the suction nozzle of vacuum cleaner across rows of keys on the keyboard to remove dirt/dust accumulated in between keys.  Hand brush may be used to assist in removing settled dirt/dust.
3. Use cloth dampens with ethyl alcohol to wipe clean the keyboard and mouse.  Do not use excessive alcohol as the disinfectant is flammable.
4. Wait until the residual alcohol has evaporated before returning the computer for normal usage.
5. Use 0.1% hypochlorite solution to wipe clean the surface of CPU and monitor casings.  Wait for 5 minutes and use another piece of cloth dampened with water to clean off residual hypochlorite.
6. The glass surface of video display terminals with cathode ray tubes may be cleaned and disinfected using diluted hypochlorite solution.
7. The video display surface of LCD monitor should be wiped gently using a damp cloth

(8d)  Clothing, Bed Sheets, Blankets, Shoes and Personal Items

Dirty and soiled items should be washed as soon as possible.  Whether bleaching agent should be added would depend on individual items.  Students should consult washing guides or instruction of the items. 

(8e)  Ventilation Fans

1. Make sure that the fan is turned off.
2. Carefully remove the guard from the fan and wash it
3. Rinse the guard in 0.1% hypochlorite solution and let it stands for ten minutes.
4. Wash the guard with water and put it aside for drying.
5. When the guard is thoroughly dried, put it back onto the fan.
6. The guard should be cleaned and disinfected on a weekly basis.

(8f)   Floor

1. Mop the floor at least once a week with 0.1% hypochlorite solution.
2. Do not enter into the cleaned area while it is still wet.

1. Use 0.1% hypochlorite solution to mop the floor and cloth dampened with the disinfectant to clean surfaces in common areas on a daily basis.
2. Cooking utensils, food containers, and cutlery should be thoroughly disinfected and rinsed. 
3. Staff working in canteens must wear masks.  Those involved in handling food must also wear gloves.

1. Use 0.1% hypochlorite solution to mop the floor and a damp cloth to wipe clean the seats, metal window grille and handlebars, etc.
2. Buses with sliding windows should be opened fully for maximum fresh air.
3. Buses without sliding windows should switch on mechanical ventilation to allow maximum fresh air intake.  Filters in the ventilation system should be cleaned and disinfected every day using disinfectant.

While common areas are handled by cleaners, residents staying in hostels and staff quarters on campus should be responsible for cleaning and disinfecting their own premises.  In principle, the guidelines listed under the sections on diluting and using disinfectant should be used.  However, the frequency of cleaning and disinfection would depend on the actual need of the residents.

(12)  Procedures for Disinfecting Lifts

1. Mop floor with 0.1% hypochlorite solutions.
2. Wall panels, including the control panel, should be cleaned witha a damp cloth with 0.1% hypochlorite.
3. Wait for 5 minutes and use another piece of cloth dampened with water to clean the control panel and any other parts of the wall panels made of metal.
4. Lifts should be cleaned more frequently, and preferably twice every day for obvious reasons.

(13)  Procedures for Disinfecting Garbage Collection Stations

1. Prepare 0.2% hypochlorite solution (1:25for regular bleach and 1:30 for concentrate bleach) outside the garbage shelter.
2. Spray the plastic rubbish bags inside the garbage trolley with the prepared hypochlorite solution.
3. Wash the external parts of the trolleys.
4. Let the hypochlorite solution to drain off.
5. Use 0.2% hypochlorite solution to wash the walls inside the garbage collection stations.  Wait for fifteen minutes and hose-spray the walls again with water.