Safetywise, Vol. 4, No. 2

Abstract

[evdate 1995-04-15] SAFETY AND ENVIRONMENTAL PROTECTION OFFICE Radon (Rn) is a naturally occurring radioactive gas. It is originated from rocks, such as granite, which contain uranium (U-238), another radioactive element. Radon tends to accumulate in in-door and enclosed areas. Its radioactive decay products were found to increase the risk of developing lung cancer in human (Figures 1 & 2). It has long been known that radon is a ubiquitous threat to in-door air quality. In recent months, the adverse health effects due to radon accumulation in concrete buildings and other , environments such as Mass Transit Railway ~ Radon-222 (a gas) Polonium-21 8 a a rea ted as uranium-238 Lead-21 4 1/ J Polonium L P -214 Bismuth-21 4 a: alpha particle p: beta particle I When these are inhaled, they ! irradiate the lung and increase the risk of develo tunnels have raised concern in the local population. For the past month, SEPO has been conducting measurements of radon level at various locations on campus. These include offices, laboratories and enclosed tunnel areas. The preliminary data show several patterns: 1) In the office environment, the 24-hour average radon levels generally range between 80 and 120 becquerel per cubic meter (Bq/m3, Bq is a measuring unit for radioactivity, 1 Bq = 1 atomic disintegration per second). In one of the laboratory surveyed, the level was even lower. 2) Radon levels built up after the daily shut down of the ventilation system in the evening. The peak level typically occurred at around 500 - 7:00 am and has been recorded between 180 and 300 Bq/m3. 3) After the ventilation system has been turned on in the morning, a rapid drop of radon level is observed. The typical level during office hours ranges between 10 and 40 Bq/m3. 4) The level at enclosed spaces such as the utility tunnel reached an average of over 300 Bq/m3.

The International Commission on Radiological Protection (ICRP) and the World Health Organization (WHO) recommend a limit of 200 Bq/m3 for domestic exposure. This means virtually continuous exposure as compared to the 8-hour per day exposure at work. Except for the enclosed tunnel areas, the 24-hour average level at our office and laboratory areas is below this 200 Bq/m3 level. At the utility tunnel where entry is infrequent and, in general, momentary, the risk of exposure to an elevated radon level is limited. However, since it is evident that the ventilation system is one of the main ways to reduce radon level, SEPO will work with EM0 to design a practical and energy efficient way to address this issue. In the case of enclosed tunnel areas, personal protective devices or mechanical ventilation system may be used to reduce exposure to radon. In our building, most of the radon appears to come from concrete materials which contain granite particles. The radon level at a particular room appears to be dependent on the number and size of concrete walls, the use of wall paper, ventilation rate, etc. Table 1 shows the calculated risk of residential exposure to different levels of radon. One can see that cigarette smoking increases the risk for lung cancer by ten folds in the presence of radon. Although the recommended limit of 200 Bq/m3 carries a 3% lifetime risk for lung cancer which may seem quite high, the average levels actually encountered at HKUST during office hours (10 to 40 Bq/m3) only present a lifetime risk of 0.15 - 0.6%. The risk is even lower for non-smokers. For comparison, the prevailing lifetime risk of lung cancer in the general population in UK is about 6%. It is also worth mentioning that since radon is a naturally occurring substance, the criteria for regulation are very different from those of man-made hazardous materials or operations. In the latter cases, the "acceptable" lifetime risk is usually set at one in a million (1 O-6) for environmental exposures (i.e. for the general population), and one in ten to one hundred thousand (1 O-4- 1 O-5) for occupational exposures (i.e. for workers). * /' This campus radon survey is'an on-going study. As we produce additional data, we will publish a more comprehensive report. Table 1. Lifetime risk of lung cancer from lifelong exposure to radon at home 20 0.3 1 0.1 40 0.6 2 0.2 200 3 10 1 400 6 20 2 l On the assumption that one person in four smokes about 15 cigarettes a day. (Modified based on Board Statement on Radon in Homes. Vol. 1, No 1, 1990. National Radiological Protection Board) / Campus (

We would like to take this opportunity to thank you for making the Audibility of alarm and announcement

recent fire drills successful. These drills had provided valuable At a number of locations, the fire alarm was found barely, or

opportunities for employees and students to gain the "practical not audible. In some areas, the announcement through the

experience" in fire evacuation procedures, and for SEPO to identify Public Address (PA) system loud speakers could not be

a number of important areas where improvements are needed to heard clearly. At the assembly points, the loud hailers could

be made. not be heard clearly. The following is a summary report of the HKUST Fire Drills 1995. Three separate fire drills were conducted consecutively from 27 February to 1 March 1995 to cover all areas of the Academic and Administration Building (Phases I and II). The dates of fire drills were announced to all staff. Phase II offices and classrooms (Zones D and E) Feb 27,1995 10:00 am Academic & administration building, Feb 28,1995 1O:OO am Library and multi-story car-park at Phase I Laboratory area at Zones H, J & L Phase II Mar 1, 1995 1O:OO am The fire drill on 28 February was a joint exercise with the Government Fire Services Department (FSD). Based on our observations during the drills, and on the feedback from Departmental Fire and Safety Officers (DFSOs) and other building occupants afterwards, we have identified a number of areas for improvement. These include: Response The majority of people in the building responded promptly to the alarm and announcement, and evacuated in a orderly manner. However, some hesitated for a while before leaving. A few contract workers refused to leave the building during the 28 February fire drill. The recorded time for the last person observed to leave the building for each drill is tabulated below: 27 February 28 February 1 March 11 .O minutes 9.4 minutes 7.0 minutes Congestion of staircase Staircases next to Lift No. 25/26 and No. 17/l 8 were found to be severely congested on 27 February. People had to walk very slowly down the stairs. Reentering building Many people started returning to the building before permission was granted by the FSD Officer-In-Charge on 28 February. We have been working with the Estates Management Off ice (EMO) in resolving the problems related to the alarm and PAsystems, and communication at the assembly points. We have reviewed the problem of congested staircases and came to the conclusion that the problem was probably due to the fact that the two staircases in question are located in the central part of the building complex, and are surrounded by frequently occupied classrooms. These two staircases are used as daily traffic routes by many staff and students since they are next to the lifts. In times of emergency, it is likely that people will use the staircases which they are most familiar with. There are in fact three other staircases which are rather close to each of the two congested staircases in question. We observed that these other staircases were under- utilized during the fire drills. We have requested concerned DFSOs to prepare and post revised departmental fire evacuation route(s) bearing in mind to direct people away from the congested staircases. We would like to ask you to study the attached map and familiarize yourself with the alternative escape routes in the areas of concern. As for returning to the building before permission is granted, please remember that the annual fire drills are a valuable exercise that may just save your life one day. So please take it seriously, and follow all instructions.

._ ,, _ . ., .. . .. I CONGESTED stairwell during 1995 Fire Drill r-ll I B ALTERNATIVE stairwell for fire evacuation L-d

I--I-r I r I 3. Note the two stairwells (near Lift 17,18; and Lift 25,26) bound by thick solid lines. These lifts and the associated staircases Please take a couple of minutes and do a mental exercise: are probably used by you frequently. And that's probably also

why they were heavily CONGESTED during the last fire drill. 1. Look at the map. Note the orientation by familiar features such as the Entrance Piazza and the Atrium. 4. Now look at the ALTERNATIVE stairwells bound by thick

broken lines. Many of you may not have used these staircases 2. This map shows the 4th floor of "Zone D and E" which have before, some may not even know they exist. Visualize in your

many offices and classrooms. Other floors are similar. If you mind their locations, and how you can go there from your off ice

are a staff with an office in this part of the building, try to locate or classroom. Next time when you are in that part of the

your off ice. If you are a student, try to find a classroom you are building, take a few more steps, push open a couple doors, and

using, or have used before. take a look for yourself at these alternative fire escape routes.

C Hazards are an everyday part of life and it is not possible to eliminate all of the hazards in our world. Indeed, some natural hazards are truly out of our control, and are referred to as m 3. Threshold Limit Value- Ceiling (TLV-C) - the concentration that should not be exceeded during any part of the working exposure. "Acts of God" by some. At best, we can try to control or reduce hazards which we encounter. One example of a class of hazard often encountered is exposure to hazardous chemicals. Industrialized societies have established exposure limits for hazardous chemicals and Hong Kong is no exception to this. For some substances, e.g., irritant gases, only one category, the TLV-C may be relevant. For other substances, one or two categories may be relevant, depending upon their physiologic action. Most exposure limits in the world have their roots in a list developed by the American Conference of Governmental Industrial Hygienists (ACGIH). The ACGIH limits are called Threshold Limit Values (TLV) and are intended to be guidelines to assist in the control of health hazards. According to the ACGIH, TLVs have not been developed for use as legal standards, although as already mentioned, almost every list of legal exposure limits in the world is based on the ACGIH TLVs. The TLVs refer to concentrations of airborne substances and are NOT suffer any adverse health affects, even with repeated daily exposure. believed to represent conditions under which most workers will However, because there In Hong Kong the exposure limits are based on the ACGIH list of TLVs as well as standards from other overseas organizations and are referred to as Occupational Exposure Limits (OELs). The OELs are adopted by the Labour Department of Hong Kong, and strictly speaking apply only to those workplace operations covered by the Factories and Industrial Undertakings legislation. In Hong Kong it is easy to change the OELs because the Hong Kong Labour Department has the authority to adjust them based on new health hazard information. Chemical TLV-TWA TLU-STEL TLV-C Acetaldehyde - - 45 Chloroform 49 - - Diethvi ether f210 1520 M&h&m chloride 174 - - Nitrogen dioxide 5.6 9.4 - Ozone 0.1* ON 0.2 and regulations. One of the It is the policy of HKUST to keep staff and student exposures to responsibilities of the Occupational Hygiene Section of SEPO is to hazardous substances within internationally accepted guidelines evaluate exposure to airborne contaminants at HKUST. This function is performed by OH team members who survey the various campus academic and support operations for potential exposures. Exposure monitoring itself consists of sampling the air in the breathing zone of personnel by using portable sampling pumps and an appropriate sampling media. Sample analysis is performed by SEPO's analytical laboratory. Sulphuric acid 1 3 - Welding fumes 5 - - Unit mglm3 *Proposed to repke the 7l.wc 11%MIA = Threshold Limit Vab77ma-Weighted AWlrag?@ TlV-STEl = Thtwhu~d timit Value-Short-Temr Ekposuf~ Limit 7X%C, = Rvesho!d timit V&b-Ceiling Extmctadfmm *7993-1394 77weshddLimit Values for Chemical Substances and Physical Agents and Bioiogicai Expasure indices" AGGIH, 1993. are population variations as well as variations in use conditions, TLVs should be applied in the particular context keeping in mind these other variables. For instance, worker exposure to airborne asbestosfibres presents a risk of lung cancer four times the "normal" risk, but an asbestos worker who smokes has at least a fifty fold higher than normal risk. There are three categories of TLVs and the ACGIH definitions for these categories are: 1. Threshold Limit Value-Time-Weighted Average (TLV-TWA) is the time-weighted concentration for a normal 8-hour workday and a 40-hour workweek, to which workers may be repeatedly exposed without adverse effect. 2. Threshold Limit Value-Short-Term Exposure Limit ( T 'LV-STEL) - the concentration to which workers can be exposed for a short period of time (no longer than 15minutes each time, and no more than 4 times per day, each time separated by at least 1 hour) without suffering from adverse health effects, and provided that the daily TLV-TWA is not exceeded. It supplements the TLV-TWA limit where there are recognized acute effects from a substance whose toxic effects are primarily of a chronic nature. So far, personnel sampling has revealed several cases of over- exposure to both research and support staff. When such situations are identified, OH staff of SEPO work with the end-users to develop strategies to reduce exposures to an acceptable level, thus allowing the operation to continue without jeopardizing the health of staff. If you have any queries about exposure limits, or need assistance in evaluating possible occupational exposure, please do not hesitate to contact us.

- -- -- - Ether and other peroxidizable chemicals such as divinyl acetylene, vinylidenechloride, potassium metal, and sodium amide, can become gerous explosion risks when they are stored for an extensive od of time. These materials, in the presence of oxygen or when I exposed to sunlight, form unstable peroxides.These peroxides may explode if the container is heated or merely shaken, as demonstrated by the cited accident. At HKUST, peroxidizable chemicals are controlled 'L~C~II 1 per Chapter 8, Section I, of the HKUST Safety and Environmental Protection Manual. Users are required to properly label these materials, record on the container the 1 recaiptdate, date when container was opened, and when oxidation A University of California, San Francisco (UGSfl prufessor was

injured by an explosion in his lab r=aused when he tipped over a pint (approximately 4 73 mL) bottle of ether on 9 March, 1995. He suffered burns and other in@%s in the explosion. A professor of pharmaceutical chemistry at UCSF for 24 years, he was cleaning his lab when he apparently knocked over the small container of ether and "that was enough to set it off%iid the dean of the UCSF School of Pharmacy Ether, a common so/vent, "becomes v81y dangerous if oxidiaeb, n he said, and can cause a serious expfosr'on. Two researchem h an ad&c& ilab quickly helped contain the f&e with extinguishers. Ffundreds of employees and students in the highrise building were quickly evacuated while a special hazardous materials team combed the area for any otherproblems. The Dean of Pharmacy also said that the professor's lab suffered extensive damage including several blown-out windows. (Partially excerpted from San Francisco Examiner, Metro--Bay Area and Northern California, March 70, 7995, page A-25) inhibitor was added. Users must strictly adhere to the recommended maximum storage period, i.e. 18 months after receipt if container was never opened, or 3 months after opening, or 3 months from the date when inhibitor was added and tests showed no peroxide formation. All peroxidizable chemicals must be properly disposed of as hazardous waste. - Opening old containers of peroxidizable materials can distut& peroxides formed in the lid and cause - After opening peroxidizable materials, it is safer to discard leftover materials as hazardous waste than to store them for long-term use. Strict adherence to these procedures will minimize'the risk of explosion caused by these chemicals. Also, in the interest of waste minimization, it is important to plan your acquisition and use of these materials carefully to avoid over-stocking and prolonged storage. If you have any query regarding handling, use, testing for peroxide, and disposal of these materials, please do not hesitate to contact SEPO.

We have established a new departmental E-mail account called SAFETY. We would like to encourage you to use this new channel of

communication to let us know about: l potential hazards on campus (however, DO NOTuse this E-mail account for imminently dangerous conditions, use the campus

emergency phone 8999 instead) l queries or comments related to campus safety and environmental protection issues

l comments or suggestions on services provide by SEPO SEPO staff will check for new mail each day, and will provide you with a prompt response.

In order to make the HKUST Safety and Environmental Protection Manual more accessible, the document has been made available

on-line through the Library for quite a while. However, with the recent reorganization of the Library on-screen menu, the Safety Manual

is now found under a different category. To get to the on-line Safety Manual: l Enter the Library Online System at the main menu l Choose C) Campus Information l You should see D) Safety Manual For more information on how to manoeuvre within the on-line Safety Manual, you can refer to the May 1994 issue of Safetywise.

Radon represents a unique combination of in-door air quality problem and radiation hazard. The health effect of radon exposure is increased lifetime risk of lung cancer, which may not be discernable for years. Nevertheless, protection of human health should never stop at just eliminating immediate health hazards. We hope the results of our recent radon survey will assure staff and students that this potential health hazard is being addressed. We believe everyone on campus has participated in this year's fire drills, which covered the whole academic building. In addition to alerting staff and students to fire hazards, and providing a chance for each one of us to practise evacuation using fire escape routes, the drills have an additional value of helping us to identify areas for improvement in the fire safety programme. The centrefold of this issue is a map which we hope will help to acquaint some of you to alternative fire escape routes in areas that were found to be congested during the drills. If your office happen to be in the areas of concern, or you regularly travel to those areas, please take some time and complete the recommended "mental exercise". You may also want to take out or copy the centre page for posting as a constant reminder. Recently, we are delighted to learn that the first batch of 150 reams of recycled paper stocked by the General Administration and Committees Office (GAC) was completely used up by various departments and offices within three months. Among the user departments which tried out the recycled paper are Physics, Biology, Library, Division of Social Science, Campus Services Office, and the Vice Chancellor's Office. We hope more people will join in later.