Rules and guidelines
Here we review the work environment regulations for Swedish-flagged ships, limit values for air pollutants in the work environment on ships and recommended guideline values for air pollutants in general indoor environments.
The UN's maritime body The International Maritime Organisation (IMO), based in London, develops international rules and recommendations for shipping. These are then implemented through the national legislation of flag states. This means that health and safety rules may differ depending on where the ship is registered. Two ships of the same shipping company registered under different flags may therefore be subject to different health and safety rules.
Many ships are also subject to other types of guidelines and instructions from classification societies, cargo owners and industry organisations. These types of guidelines often place higher demands on the work environment and safety than the law prescribes. For tankers, for example, there is ISGOTT, the International Safety Guide for Oil Tankers and Terminals, a comprehensive international industry-wide recommendation for how ships and quayside facilities should be designed and how they should interact with regard to safety, health and the environment in connection with the handling of petroleum products.
Below you will find a more detailed description of the work environment regulations for Swedish-flagged ships, general guidelines and recommendations for indoor air quality, and tables summarising limit and guide values for gaseous substances, particles, temperature and relative humidity.
Work environment rules for Swedish-flagged ships
The work environment on Swedish-flagged ships is regulated by the Swedish Transport Agency's provisions and general advice on the work environment on ships. These provisions bring into force a selection of the Swedish Work Environment Authority's regulations, including the rules on chemical hazards, occupational exposure limit (OEL) values, and rules on workplace design that concern ventilation and air quality.
The management of the shipping company has overall responsibility for the health and safety of its employees. The master is generally responsible for the work environment on board. Both international requirements for a functioning safety management system and Swedish requirements for systematic work environment management (SAM) mean that the work environment must be regularly examined and risk assessed. Risks of ill health and accidents must be addressed and followed up. The requirements apply to all parts of the work environment - physical, organisational and social - and these parts often interact.
Chemical hazards in the work environment
Chemical hazards in the work environment must be remedied as far as possible. The work environment rules mean that all employers are obliged to regularly examine and risk-assess the work environment to determine what measures are required to ensure that work is safe. The Work Environment Act states that measures to reduce chemical work environment risks in the workplace should be based on a so-called action ladder. This means that as far as possible, risks should be avoided or limited by common technical or organisational measures. The last step in the action ladder is personal protective equipment. It should be used when it is not possible to limit the risk further with other measures.
Workplaces should have satisfactory air quality in the occupied zone. As far as possible, the air shall be free from pollutants that may be harmful to health or cause unpleasant odours. Ventilation systems shall be designed to supply sufficient outdoor air and remove air pollutants. Indoor workplaces should have a suitable thermal climate. The temperature and air speed need to be adjusted depending on whether the work is light or heavy, active or sedentary. If different tasks take place in different parts of a room, the rooms may need different thermal climates.
Occupational exposure limit (OEL) values
The Swedish Work Environment Authority's occupational exposure limit (OEL) values for respiratory exposure specify the highest acceptable average concentration of a substance in the air at the workplace. The values apply for personal exposure, calculated as a time-weighted average. Swedish and international OEL values to hazardous substances are based on the scientific studies of known dose-response effects, i.e. how high doses of a substance people can be exposed to without suffering acute or long-term health effects. Limit values form the basis for decisions on how long it is permissible to work in a given atmosphere, based on the type of substance and concentration. The occupational exposure limits values are expressed as time-weighted average or short-term exposure limit values.
Threshold Limit Value – Time-Weighted Average (TLV-TWA): time-weighted average concentration of a hazardous substance in the air averaged over an 8-hour workday and a 40-hour workweek to which it is believed that workers may be repeatedly exposed, day after day, for a working lifetime without adverse effects. Threshold limit values are binding and must not be exceeded. At sea, working days longer than 8 hours are common. In this case, a standardised method can be used to calculate the level where the limit value is multiplied by 8/x where x is the length of the working day in hours. Longer working hours mean a lower limit value.
Threshold Limit Value – Short-term exposure limit (TLV-STEL): time- weighted limit value for respiratory exposure during a reference period of 15 minutes (for some substances 5 minutes). An exposure equivalent to a 15-minute short-term limit value should not be exceeded at any time during a workday, even if the overall 8-hour time-weighted average concentration is below the limit.
The OEL values apply provided that the persons exposed do not carry out highly physically demanding tasks that increase breathing and thus the absorption of air pollutants.
General guidelines and recommendations for indoor air
The WHO's International Agency for Research on Cancer (IARC) expert group has categorised nearly 1 000 agents (active substances) into five groups according to their perceived carcinogenicity. Risk group 1 means that the substance is a known human carcinogen, group 2A that the substance is probably a human carcinogen, and group 2B that it is possibly a human carcinogen.
Limit values for respiratory exposure in the working environment are adapted to industrial workplaces where employees stay for shifts of typically eight hours. On ships, the situation is slightly different as employees both work and live on board for longer periods of time than is normally the case in a land-based workplace. To get an idea of how measured levels relate to other environments, they can be compared to the World Health Organisation's health-based guideline values for indoor air (WHO, 2021). These guideline values are developed for ambient air but they also apply to residential and other non-industrial environments. The WHO’s guideline values are significantly lower than the hygienic limit values and should not be exceeded. Measured levels can also be compared with measurements from homes and offices, as well as for other relevant occupational groups.
In Sweden, the Public Health Agency has produced general advice on thermal indoor climate in homes and public premises. The advice includes recommendations for temperature, relative humidity, and draughts when most people experience good thermal comfort. The advice also includes guideline values when the indoor climate may be a nuisance to human health. Although the advice is not specifically aimed at on-board living environments, it gives an indication of the quality of the indoor climate that should be maintained for good comfort and not pose a direct or indirect health risk.
Summary of air pollutants
Tables 1-3 summarise the air pollutants included in this material. The tables contain information on the pollutant's IARC Risk Group, occupational exposure limit values, World Health Organisation's health-based guideline values, as well as previously measured concentrations in general indoor environments, such as homes and offices, for comparison. Table 1 shows limit values and guideline values for gaseous air pollutants and Table 2 for dust and particles. Table 3 summarises parameters for thermal climate.
Concentrations measured on board Swedish ships are compiled in the database
External link, opens in new window..
Table 1. Overview of gaseous substances included in the knowledge bank.
Pollutant | IARC risk | TLV-TWA | TLV-STEL | WHO guidelines for indoor environments | Indoor environments (homes, offices) |
|---|---|---|---|---|---|
Benzo(a) pyrene | 1 | 2 µg/m3 | 20 µg/m3 | 0,0012 µg/m3 | 0,0000005 – 0,0005 µg/m3 |
Benzene | 1 | 1 500 µg/m3 (0,5 ppm) Från april 2026: 660 µg/m3 (0,2 ppm) |
9 000 µg/m3
| 1,7 µg/m3 | 0,6 – 25 µg/m3 |
Formaldehyde | 1 | 0,37 mg/m3 | 0,74 mg/m3 |
100 µg/m 3
| 4 – 160 µg/m3 |
Carbon monoxide | --- | 23 mg/m3 (20 ppm) | 117 mg/m3 (100 ppm) | 4 mg/m3 (3 ppm) daily average | Not usually measured in homes and offices |
Carbon dioxide | --- | 9 000 mg/m3 (5 000 ppm) |
18 000 mg/m3
| 1 000 ppm instantaneous value | 400 – 2 000 ppm |
Nitrogen dioxide | --- | 960 µg/m3 | 1 900 µg/m3 | 25 µg/m3 daily average 10 µg/m3 annual average | 3 – 40 µg/m3 |
Naphthalene | 2B | 50 000 µg/m3 | 80 000 µg/m3 | 10 µg/m3 | <0,00001 – 26 µg/m3 |
Ozone | --- | 0,2 mg/m3 | 0,6 mg/m3 | 100 µg/m3 8h mean value | 0,1 – 97 µg/m3 |
Sulfur dioxide | --- | 1 300 µg/m3 (0,5 ppm) | 2 700 µg/m3 (1 ppm) | 40 µg/m3 daily average | Not usually measured in homes and offices |
TVOC | --- | --- | --- | 200 – 300 µg/m3 | 40 – 420 µg/m3 |
Table 2. Summary of dust and particles included in the knowledge bank.
Pollutant | TLV-TWA (8h) | TLV-STEL | WHO guidelines for indoor environments | Indoor environments (homes, offices) |
|---|---|---|---|---|
Inorganic dust, respirablelt | 2,5 mg/m3 | --- | --- | Not applicable |
Inorganic dust, inhalable | 5 mg/m3 | --- | --- | Not applicable |
PM2.5 | --- | --- | 15 µg/m3 5 µg/m3 | 2 – 430 µg/m3 |
PM10 | --- | --- | 45 µg/m3 15 µg/m3 | 2 – 1200 µg/m3 |
Elemental carbon | 50 µg/m3 | --- | --- | 0.5 – 7 µg/m3 |
Table 3. Summary of thermal climate parameters included in the knowledge bank.
Parameter | Working environments | General indoor environments | Indoor environments |
Temperature | 20-24 oC wintertime | 20 – 24 degrees C | 19 – 24 degrees C |
Relative humidity | --- | 25 – 60 % | 25 – 57 % |