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On PMWs and Two-Strokes Engines

On Saturday, August 24/96, a 40 year old man from Edmonton, Alberta, was riding a personal motorized watercraft (PMW, a Seadoo- or Jet Ski-type of machine) on Shuswap Lake, in south-central B.C., approximately 200 metres offshore. The man motioned for his sister, who was riding another PMW, to follow him across the lake. She did so, but as she turned her head to check for other boat traffic, her brother suddenly slowed down and his sister's machine rode right up on his back, crushing him against his handlebars. His sister, a nurse, held her brother's head above water until help arrived, but 48 minutes after the moment of impact he was pronounced dead at the Shuswap Lake General Hospital. He had suffered a ruptured aorta.

PMWs are single or two-seated machines powered by self-contained 30- to 40-horsepower motors, designed almost exclusively for recreational use. They are easily transportable, travel at high speed, produce high-intensity, high-pitched, constantly fluctuating motor noise, and possess a uniquely short turn radius and shallow draught. They are almost all powered with two-stroke gasoline motors. Bombardier Inc., a major manufacturer of PMWs, sold $1.6 billion worth of machines in 1995, with sales in the industry estimated to be increasing 10-30% yearly.

This editorial is written to inform family physicians of the unusual risks to human and ecological health posed by PMWs.

Data from the Canadian Hospitals Injury Reporting and Prevention Program (CHIRPP) revealed 48 injuries involving PMWs between 1990 and 1995. Nearly half (46%) involved operators age 19 and under, 65% involved males, and the head was the most frequent site of injury (42%) . These statistics are undoubtedly incomplete.

The US Centers for Disease Control reported last summer that while injuries from PMW use increased fourfold (2,860 in 1990 to more than 12,000 in 1995) the number of users grew only about threefold (241,500 to greater than 760,000).

The U.S. Coast Guard recorded 3,002 accidents involving PMWs in 1994, comprising 1,338 injuries and 56 deaths; the Coast Guard estimated that only 10% of non-fatal accidents were actually reported. Further Canadian and American documentation suggests that injuries involving PMWs can be serious, are disproportionate to the number of machines being used, and frequently involve young or inexperienced operators.

However, beyond the direct injuries wrought upon humans by the use of PMWs, there is a whole range of indirect health effects, many of them caused through environmental damage and ecosystem destruction.

PMWs are noisy. One author (A.Y.) tested noise levels from a single PMW with a Quest-M27 noise dosimeter, and found levels up to 83 dBA at 10-15 metres distance, with one-minute average levels as high as 75 dBA. Noise levels with various PMWs range from 80-105 dBA, and the noise varies because every time a machine passes over a wave, its jet drive emerges from the water, resulting in rapid fluctuations from high to low pitch and intensity; such variable sounds are much more disturbing than constant ones . Not only does such noise disturb humans, however. It is intensely and profoundly disruptive of bird and aquatic mammal habitat as well.

PMWs also disturb the clarity of shallow water, with significant effect on fish and other aquatic life. One small control study showed vastly increased turbidity and suspended solids in river water following transit of a single PMW.

PMWs are highly polluting. Almost all are powered by inefficient two-stroke gasoline engines, the same kind used in most lawnmowers, many off-road recreational vehicles, and all chainsaws. These engines use gasoline directly mixed with oil. When used in PMWs, they discharge approximately 25% of their fuel unconsumed into the water, contaminating it with highly toxic and carcinogenic benzene and toluene.

Two-stroke engines also produce vast amounts of air pollution relative to their power output. It is estimated by the U.S. Environmental Protection Agency that running a two-stroke, 70 hp. motor for two hours produces more airborne hydrocarbon pollution (including significant amounts of carcinogenic polycyclic aromatic hydrocarbons or PAH) than driving a car 8000 kilometres using the more efficient four-stroke engine. It is estimated that every year, two-stroke engines alone generate water pollution equivalent to the sinking of 15 Exxon Valdez oil tankers, and more than from any other point source.

The PMW, and the two-stroke engine that it contains, are examples of industrial technology that has proliferated without much reflection taking place on health or environmental consequences. As members of the Canadian Association of Physicians for the Environment, a national Canadian non-profit organization of doctors, other health professionals, and environmental scientists, we are appalled by the cavalier attitude that underlies the use of such devices. Not only do we see concrete damage caused by PMWs on our patients, but we have informed ourselves about the startling levels of environmental degradation they are producing on a daily basis. Fortunately, we are not alone in our concerns.

Increasingly, environmental groups such as the Earth Island Institute (through its subsidiary, the Bluewater Network) and the Sierra Club are taking on the challenge of restricting PMW use. This process has involved three stages.

First, activists and concerned health personnel and biological scientists have united to present accurate facts and figures relating to the use of these devices. Such information is necessary to counter the flood of inaccurate and misleading material offered by the multinational corporate manufacturing sector which produces PMWs. This article is an attempt in that direction.

Second, the above groups have pressured governments in small and large jurisdictions to bring in regulations to decrease the danger of using PMWs, and to reduce their pernicious effects on air and water quality and habitat integrity. Switzerland has outlawed PMWs on Lake Constance, and prohibited the sale of two-stroke engines in the country. The state of California, under pressure of a lawsuit from the Bluewater Network, has embarked on restrictive legislation, and the U.S. National Park Service is considering regulations restricting PMW use in national parks. San Juan County in Washington State (essentially an archipelago of small islands), in January, 1996, established an ordinance banning PMW use entirely within its waters; despite intense, lavishly funded opposition from the manufacturing industry (coordinated by the National Marine Manufacturers Association or NMMA), the County recently won its case in the Supreme Court of Washington State. It is not clear if the PMW industry will appeal.

Regulations are now pending in Canada that would involve mandatory training for PMW operators, establish lower limits for the age of operators, and introduce other controls that would enhance the safe use of these machines.

Third, concerned parties have promoted an alternative to the highly polluting two-stroke engine that powers 98% of all outboard motorboats and 100% of PMWs. It is the standard small four-stroke engine, manufactured for the last 25 years by Honda and others. The difference between the two motors in terms of pollution is startling. Four-stroke motors emit 97% less air pollution than their two-stroke counterparts. In numbers, the four-stroke emit about 4 gm of hydrocarbon per Kilowatt/hr of energy produced, vs 150 gm per Kwh for the 2-stroke equivalent. Moreover, despite a 15% higher purchase price, 4-stroke motors are four times more fuel efficient than two-stroke ones; thus owners can rapidly recoup their initially higher investment.

Unfortunately, despite the efforts of advocacy groups, the US EPA has elected to work closely with the NMMA and ignore concerned public advocacy groups. New standards involving an absurdly lengthy phase-in period have been set for decreasing two-stroke pollution; they would produce a 50% reduction in total hydrocarbon emissions only in the year 2020! We are not aware of any efforts by any Canadian jurisdiction anywhere in the country to limit the use of either PMWs or two-stroke engines.

Much remains to be done to change this intolerable situation. Legislation like the pending Canadian Environmental Protection Act, which would provide tools for challenging PMW use, must be promoted. Community governments must be made aware of these problems, something physicians with our considerable credibility can do better than most. We invite concerned colleagues to join us and add their voices to the growing protest over the pollution of Canada's waterways and air space by PMWs and the outmoded two-stroke motors they contain. The direct adverse effect of these devices on human health is considerable. The indirect effects, like a slow-burning fuse, will explode not in our faces, but in the faces of our children and grandchildren.

Ought we not to pass on a planet in better condition than we have found it -- or at the very least, make a sincere effort in that direction?

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