1 INTRODUCTION

It is now common knowledge that all sorts of airborne contaminants are present in the workplace. Gases, vapours, dusts, fibres, pollens, insect fragments, bacteria and fungi and their spores, plus viruses all contribute to indoor pollution. Certainly many of the pollutants can adversely affect the health of humans as evidenced by the multiple deaths from Legionnaires' disease or the risks from radon, asbestos or the myriad of substances included in volatile organic compounds that are released from adhesives, plastics, gasoline, pesticides, synthetic materials, particle board, smoking, internal combustion engines, operations including cleaning, cooking, copying, etc., and even from natural processes such as respiration, body odours or microbial decay.

Despite the multiplicity of sources of indoor contaminants, one source of airborne substances had become a focal point of intense public scrutiny - tobacco smoke. Certainly there are few topics of conversation more likely to stir emotion and create heated debate than the issue of cigarette smoking. Very few people claim a truly neutral attitude towards this issue. Between twenty-five percent and fifty percent of adults smoke depending on the country concerned. This means that another fifty to seventy-five percent of the general public may be eventually exposed to some level of tobacco side products.

Certainly if smoking is practiced in an enclosed, unvented area, the air within that area begins to accumulate byproducts of the tobacco combustion process as well as all other indoor pollutants. Undoubtedly, these byproducts and other substances, if they accumulate, may be considered unpleasant and irritating to non-smokers in the same situation.

Furthermore, concerns over the long term health risks from other people's smoke have recently been fuelled by the statement from the U.S. Environmental Protection Agency (EPA) that in their opinion environmental tobacco smoke contributes to lung cancer and increases the risk of respiratory illnesses in children.

This decision is likely to have considerable impact on the indoor work force throughout the USA and elsewhere. However, since the U.S. EPA has no specific authority to regulate indoor air pollution, immediate changes may not be apparent. Perhaps the first policy decisions influenced by the U.S. EPA's statement will be those from the U.S. Federal Occupational Safety and Health Administration (OSHA). This agency is currently at the formative stage of developing rules on indoor pollution in the workplace.

OSHA, of course, is well experienced in the management and control of toxic chemicals in industry. In the case of well documented carcinogens such as radon, asbestos, arsenic and benzene, it is their practice to ensure that airborne concentrations of these substances be controlled within the limits of their specified Threshold Limit Values (TLVs). The American Conference of Governmental Industrial Hygienists state that TLVs refer to airborne concentrations of substances and represent conditions under which it is believed that nearly all workers may be repeatedly exposed day after day without adverse health effects.

Since no TLVs currently exist for tobacco smoke, and in the absence of any formal government regulations concerning smoking issues in the private workplace, it would be prudent for management to take steps to adopt a workplace smoking policy. The aim of such a policy would be to minimise the exposure from tobacco smoke to all non-smokers.

2 SMOKING AND INDOOR POLLUTION

For example, attempting to design the perfect environment with respect to temperature alone can at best only satisfy ninety to ninety-five percent of the occupants, leaving five to ten percent dissatisfied owing to variances in the physiology and tolerance levels of the people concerned. The goal in writing a formal smoking policy should be aimed at satisfying as many of the building occupants as is possible and to reach a firm commitment to a workable compromise.

Note: Usually the precursor of a perceived need for a specific smoking policy is a series of complaints from annoyed staff. Individuals may experience smoke accumulation within their work area and thus justifiably complain if the smoke annoys them.

Management is well advised to take such a complaint seriously. The first course of action however, should be to investigate the cause of the smoke accumulation. In most instances this is a symptom of deficiencies in ventilation. When such faults exist, numerous unwanted events occur. If visible smoke is trapped, then invisible pollutants are also trapped. Many such pollutants can seriously affect the productivity of the employees. Bacteria, fungi and specific allergenic dusts trapped in under- ventilated areas can lead to permanent allergy problems in exposed staff. Infections may develop. Chemical substances in the air can also adversely impair the exposed. Naturally the smoke itself contributes to such irritation, but is not necessarily the cause. It is incumbent on the management to correct the long term problem - poor air quality - and then address the issue of smoking.

The fact is that many forward-thinking managers who see the "big picture" achieve best results. A professionally conducted indoor air quality audit of the workplace will identify existing or potential problems areas. Attention to such faults usually results in dramatically improved air quality. Staff morale improves, absenteeism drops, productivity increases and usually the precursor of the problem, the smoke accumulation, evaporates. This is truly a win-win solution for staff and management alike.

3 RESTRICTED SMOKING PRACTICES

3.1 Designated Smoking Areas

With some thoughtfulness in the selection of the smoking areas with respect to prevailing ventilation conditions, the policy of designated smoking areas may work very satisfactorily.

A prerequisite of any workplace that wishes to provide a comfortable and productive environment for its staff is to first ensure that generally accepted ventilation rates prevail. Specifically, for offices, restaurants, hotels, bars, etc., the ventilation rates should comply with the Australian Standard A.S. 1668-2-1991 "Mechanical Ventilation for Acceptable Indoor Air Quality".

In the case of offices, A.S. 1668-2-1991 stipulates a minimum outside air ventilation rate of 10 L/sec/person. This Australian Standard allows for a moderate amount of smoking and, when properly adopted, complaints are unusual.

While not eliminating all trace of smoke from the environment, physical grouping of smokers and non-smokers in discreet areas frequently obviates the concern of sensitive non-smokers. In doing so, care should be given to the prevailing air currents and routes of supply and exhaust air. Whenever possible, the smoking areas should be concentrated closer to exhaust systems such that the air movements will be directed from non-smoking areas to smoking areas and then to exhaust, thereby minimising migration of tobacco smoke from smoking to non-smoking areas.

In buildings meeting A.S. 1668-2-1991, the return air, including smoke from the designated areas, must be diluted by outside air and be appropriately filtered prior to returning to the supply system. With such provisions, it is unlikely that office occupants will be able to differentiate between totally smoke-free air and this recycled air. Thus, complaints are rare and many buildings operate very successfully in this way.

3.2 Air Cleaning Equipment

In designated smoking areas, supplementary air cleaning offers some worthwhile advantages. Equipment marketed specifically for removal of tobacco smoke components from room air include electrostatic precipitators, activated charcoal filters and high efficiency filters such as HEPA filtration units. All three have their place in removing substances from the air. The electrostatic precipitators and HEPA filters are very efficient at removing the finer so-called respirable suspended particulates (RSP) from the air. Correctly sized, well-serviced electrostatic precipitators or HEPA filters can remove ninety to ninety-eight percent of these airborne particles. Neither of these filters, however, can remove gaseous components. Here we need the use of adsorbent filters using activated charcoal, potassium permanganate impregnated aluminium oxide pellets or other proprietary adsorbents. These, again presupposing they are sized correctly and serviced regularly, can remove substantial amounts of unpleasant odours, gases, nicotine, etc.

The most effective means of removing perceived signs (olfactory or visual) of tobacco smoke appears to be a combination of a "roughing" filter followed by an electrostatic precipitator or HEPA unit, followed by an adsorbent filter. Several proprietary designs of this combination are readily available worldwide. The combination of separate smoking and non-smoking areas coupled to the use of supplementary filtration in the smoking sections and presupposing adequate ventilation rates, i.e., A.S.1668-2-1991 rates, is usually more than adequate to satisfy both smokers and non-smokers.

3.3 Physical Separation

Proper engineering of the ventilation systems, including provisions for the correct air flows from non- smoking areas to smoking areas to exhaust can obviate the need for physical barriers between smoking and non-smoking areas. However, there is a growing pressure from some non-smoking groups towards physical separation between smokers and non-smokers. Also, once physical barriers separate these two groups, there are further demands to move towards separate ventilation systems. Fortunately, such designs are relatively easy to accommodate into most buildings. The following section reviews the possible design options.

3.4 Smoking Room Design

3.4.1 Australian Standard A.S. 1668-2-1991

Dedicated smoking lounges can be set up in most buildings. Separate make-up air conditioning units can be supplied to these areas using the A.S. 1668-2-1991 suggested ventilation rate of 25 L/sec/person. Then to preclude the migration of smoke from the lounge back into the central ventilating systems, the lounge should be fitted with exhaust ventilation to the exterior.

Naturally the installation of make-up air conditioning systems and the retrofitting of exhaust systems to these areas costs money. However, many property owners, desirous of maintaining existing clients or of attracting new tenants find this to be very worthwhile. They can, for modest expenditure, offer an added amenity to their customers. Furthermore, when properly installed, the advantages of this system are clear - no re-entrainment of smoke into other areas and therefore no grounds for non-smokers to complain. This type of design is preferred by the U.S. EPA who state in their "Indoor Air Facts" Sheet No 5 (June 1989) on Environmental Tobacco Smoke: "The most effective way to minimise exposure is to restrict smoking to smoking areas that are separately ventilated and directly exhausted to the outside".

3.4.2 Smoking Lounge - Energy Recovery Units

Arguably, the only real objection to the smoking lounge/exhaust air design is that of cost to the owner/operator of the building. Some owners may object to the small premium it costs them to ventilate the smoking lounges. Many of these objections can be overcome with the use of Energy Recovery Units (ERUs). In recent years the efficiency of ERUs has improved dramatically and their costs have dropped thanks to mass production. Their principle is simple:

The air exhausted from the smoking lounge is passed across a heat recovery wheel, thereby transferring its heat to the wheel. The wheel rotates from the exhaust air stream to the incoming supply air stream.

Thus, on cold days, the incoming air is heated, on hot days it is cooled. With energy recovery efficiencies of seventy to eighty percent, such systems substantially reduce the operating cost of ventilation in the designated smoking areas.

3.4.3 Smoking Lounge - Transfer Air

Every building is by law equipped with toilets. All toilets have to be equipped with exhaust ventilation to remove odours, germs, etc. To ensure ease of operation, it is usual to fit such toilets with exhaust systems only. Each draws its supply air from adjacent areas. Corridors, offices, etc. close to the toilet are not fitted with the powerful exhaust fans of the toilet. Therefore, the suction of air from the restroom creates a negative pressure in the restroom relative to the adjoining areas. Air, like water always flows from a high pressure area to a low pressure area. Thus, air is transferred from the adjacent rooms into the toilets and logically this air is called transfer air. If the exhausts in the toilets are working, the system is infallible and the presence of the negative pressure in the toilets means that when the doors open, air moves from outside the toilet to the inside, guaranteeing no transfer of odours or germs.

This same system provides an obvious low cost design of a smoking lounge. With judicious selection of designated smoking areas and a brief review of the building's overall ventilation capacity, low cost smoking lounges can be provided.

Small rooms are simply fitted with exhaust air capability. Sometimes it is feasible to tap into existing exhaust ducts or shafts. The provision of exhaust air rates of 25 L/sec/person will meet A.S. 1668-2-1991 recommendations. Grilles can be fitted to the smoking lounges to allow transfer air to move from adjacent offices or corridors as per the toilet design. The result is a smoking room with dedicated local exhausts precluding recirculation of air to other areas. Furthermore, the negative pressure in the room ensures that no smoke or air spills out of the room when the doors are opened - the reverse occurs. The design is the preferred course to take to minimise both installation and operating costs. Small exhaust fans required for such rooms prove very cheap to operate, however, a ventilation specialist should be consulted to ensure that sufficient ventilation air is present in the building to service one, two, three or more such lounges for each ventilation system.

3.4.4 Smoking Lounges - Displacement Ventilation

In the design of new facilities or during any remodelling of existing facilities, consideration could be given to the design of an ultra efficient smoking lounge. The principle of operation of choice is that of displacement ventilation. This concept has been championed by the Scandinavians and Germans, among others. In fact, the success of this design has culminated in the adoption of displacement ventilation for all areas of the new Parliament Building of the Federal Republic of Germany.

Thermal Displacement Ventilation involves the supply of cool air with low velocity and low turbulence at a low level in the room, and exhaust at a high level from the room. The cool air will rise by natural convection, being trasported upwards at the heat sources (people and equipment) within the space. This means that all substances present in the indoor air, such as dusts, skin scales, tobacco smoke, body odours, microbes, exhaled breath, etc. will all rise vertically above the room occupants and be removed into the exhaust located in the ceiling. Since most of the emissions of pollutants from human activities are warm relative to the surrounding air, there is a natural tendency for them to move upwards on thermal currents. The upward flow of ventilation air speeds up this process in this displacement ventilation design and is thereby particularly appropriate for smoking lounges.

4 CONCLUSION

Some managers have already acted to ban smoking completely. Others have found that smoking in their building has never been an issue of concern. The latter is especially true in buildings that are well ventilated. This is evident in A.S. 1668-2-1991 which bases its ventilation standards on current assessed levels of smoking for listed occupancies. This includes the 10 L/sec/person standard for offices.

Employees who choose to restrict smoking to designated areas will, however, be encouraged by the news that ventilation engineering can adequately cope with removing smoke from dedicated smoking rooms or lounges. Furthermore, careful design of such areas can totally eliminate any migration of smoke to non-smoking areas. Also, such practices are not necessarily expensive. In fact, when handled properly, a smart manager can turn the provision of smoking areas into valuable assets. No building landlord wishes to lose tenants. If smokers complain of lack of access to smoking quarters or if non-smokers complain of exposure to tobacco smoke, the landlord needs to find a solution. Fortunately, this is one problem that can be resolved to the complete satisfaction of both parties. A well designed lounge will clearly be identified as an added building amenity.