Knowledge from three research projects

Measurements were performed on ten ships during eleven measurement campaigns. On one of the ships, the same measurements were made during both winter and summer time. Another vessel underwent the same measurements when running on two different types of fuel. The investigations on board included measurements of temperature and relative humidity describing the indoor climate, the levels of the gaseous air pollutants carbon dioxide, nitrogen oxides, sulphur dioxide, volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs) and formaldehyde. In addition, particles of various sizes were measured in machinery spaces and indoor environments. On two of the ships, personal exposure to nitrogen dioxide, total volatile organic compounds (TVOCs), benzene and PAHs was also investigated. On both ships, measurements were carried out on two different occasions with different conditions.

Results

The results show that the indoor environment on Swedish ships is generally good, but there were differences between both different ships and different occupational groups of seafarers', with engine crew being exposed to the highest levels of air pollutants. All measured levels were below the Swedish Work Environment Authority's hygiene limits, but some levels were slightly above the World Health Organisation's health-based and stricter guidelines for indoor environments. These guideline values are set for general indoor environments without industrial activities, but the comparison still reminds us that it is important to work systematically to minimise the exposure to hazardous air pollutants as far as possible.

Recommendations

For existing ships, the main issues are the inspection and maintenance of ventilation systems, the tidiness of machinery spaces in particular, and the use of appropriate protective equipment where necessary. In the planning and design of new ships, the propulsion system of the ship and its fuel should be considered, as the use of fuels of better quality than heavy fuel oil also improves both air quality and the working environment on ships. Another important aspect for maintaining a good indoor environment is a ventilation system that effectively separates exhausts from machinery spaces from fresh air intakes to other indoor spaces. In addition, the design of workplaces and indoor environments is of great importance, with particular emphasis on a separate cleaning room in the machine room.

The survey of seafarers' personal exposure to air pollutants included measurements of benzene, nitrogen dioxide and polycyclic aromatic hydrocarbons (PAHs), all of which can be traced to the ship's fuel and fuel exhaust. In addition, the crew's own perceptions of air quality on board were investigated through a questionnaire completed by a total of 308 people.

Results

The results show that all measured personal exposures were far below the Swedish Work Environment Authority's hygienic limit values. Some people have been exposed to levels in line with and in some cases slightly above the World Health Organisation's health-based recommended guideline values for indoor environments. However, these guideline values are set for indoor environments without industrial activities. The results indicate the importance of working systematically to minimise exposure to hazardous air pollutants as far as possible. The World Health Organisation states that there are no safe levels of benzene and benzo(a)pyrene. Therefore, tasks involving somewhat higher exposure to these hazardous substances may require special risk assessment, such as tasks involving contact with fuels, lubricating oils, hydraulic oils or other chemicals, exposure to engine exhaust gases or cooking fumes.

In a comparison between positions and departments, we see that engine crew generally have the highest exposures, followed by staff in the deck department and the maintenance department, who have the lowest exposures. No difference in exposure could be observed when comparing the results for officers and ratings. The results of the questionnaire survey show that indoor air quality is generally perceived as acceptable. The deck and engine departments are more satisfied with their air quality than the service crew.

Exposure to more than one substance with a similar effect is known as an additive hygiene effect. A cumulative risk index has therefore been developed as the sum of the ratios between the measured concentrations of nitrogen dioxide, benzene, benzo(a)pyrene and naphthalene, and their respective health-based guideline values developed by the World Health Organisation. This risk index has been used to compare the seafarers’ exposure with the general population in Sweden, and to identify differences between ships, positions and departments. The cumulative risk index can be used for risk assessments of jobs and tasks to eliminate and minimise known exposures as far as possible.

Recommendations

Measures to reduce personal exposure can be both technical and organisational. It is important to ensure good general ventilation in both workplaces and cabins. In some areas, such as welding and machining workstations, cleaning of engine parts, mixing of paints, over frying tables in the kitchen, etc., special extraction may be required to capture air pollution close to the source. Alternatively, existing extractors may need to be improved. Good cleaning and maintenance procedures for work equipment and ventilation systems are also important. Organisational measures can include planning and distributing work to reduce individual exposure through job rotation, job changes and opportunities for breaks in lower-exposure areas.

Differences in the perception of air quality between departments can be partly explained by the different types of work tasks and exposures experienced by staff in each department. However, the experience is also influenced by psychosocial factors in the work environment, such as high workload, high demands at work and little opportunity to influence their work situation, as well as low social support and low job satisfaction. Here, quite different types of work environment measures may need to be discussed to increase the experience of influence, participation and support at work.

During the years 2018-2021, measurements were carried out on six different ships with a total of 50 people. The study covered the following operating options: ULSFO, an ultra-low sulphur hybrid residual fuel, lithium-ion battery in combination with marine diesel, LNG (liquefied natural gas), methanol (in combination with marine diesel operation) and heavy fuel oil operation in combination with scrubbers for flue gas cleaning.

The ship's indoor environment was investigated by stationary measurements of temperature, humidity and carbon dioxide, as well as levels of the air pollutants sulphur dioxide, nitrogen oxides, total volatile organic compounds and polycyclic aromatic hydrocarbons. Personal exposure of the crew was assessed for nitrogen dioxide, total volatile organic compounds and polycyclic aromatic hydrocarbons. A questionnaire on perceived workplace and cabin air quality was completed by 94 people.

Results

The results show that all concentrations from both stationary measurements and personal exposure were well below the Swedish Work Environment Authority's hygiene limits. Most levels were also lower than the health-based guidelines used for comparison. Machinery spaces were often more contaminated than other spaces on board, especially with regard to substances evaporated from fuels and lubricants or substances from engine exhaust. Increased exposure was observed for engineers involved in tasks related to the ship's fuel system. Otherwise, no difference in personal exposure was observed between officers and crew.

The results of the questionnaire survey on the crew's perception of the working and indoor environment showed that the air quality on board was generally perceived as good, both in the workplaces and in their own cabins.

The health-related cumulative risk index could not distinguish between the primary fuel types. The assessment of the health aspect of the indoor environment on board ships becomes unclear mainly due to the use of secondary fuels. For ships with the same or similar functions, battery power, low-sulphur fuel and LNG were better options than heavy fuel oil and marine diesel. A very clear improvement in the indoor environment and crew exposure, as assessed by the health-related cumulative risk index, could be demonstrated for those ships that had switched to a cleaner fuel option.

All options have characteristics and risks that require special consideration in the design of systems, operation and maintenance procedures, training and emergency procedures. Risk assessments must therefore cover both the risk of serious injury and illness and the duties can be performed in a satisfactory manner. All liquid fuels are considered toxic, with the exception of natural gas. Methanol is acutely toxic, both by ingestion and through skin exposure. However, it is not carcinogenic.

As all the ships in the study still have systems to run on petroleum-based fuels, few tasks have disappeared completely and none of the operating options involve reduced direct costs for personnel. However, there are differences in how often different tasks need to be performed and under what conditions. Cleaner fuels reduce the need to clean components and engine spaces. This in turn means less exposure to hazardous substances and more time for other, more value-added tasks.

Recommendations

As many shipboard jobs involve simultaneous exposure to several known risk factors, a holistic approach is needed that includes preventive measures and long-term health promotion work. It is not enough to target only the worst exposures.

In summary, the results of this survey show that there is no single best solution for all ships, regardless of type, cargo or trade. Whichever operational option is chosen, it is more costly than the conventional solution of heavy fuel oil combustion engines. It is likely that the energy transition in shipping will require financial incentives and harmonised regulations to accelerate the development of solutions that are both sustainable from a life-cycle perspective and commercially viable. For a sustainable and attractive working life in sustainable shipping, future solutions must also ensure that operation and maintenance can be carried out in a satisfactory manner, with the lowest possible risk of illness and accidents.