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Better control of chemicals

Shaker room offshore Photo: Anne Lise Norheim
Photo of factory chimneys Photo: Illustrasjonsfoto

Many workers handle or are in contact with carcinogenic substances at work. Exposure limits for benzene have been much reduced by new learning and the great attention paid to this chemical compound. Diesel exhaust fumes are now also in the spotlight.

The PSA has worked for many years to increase the industry’s knowledge about and awareness of chemical health risks, with a particular concentration on benzene. 

“Research shows a clear link between contact with benzene, even at low levels, and the risk of lymphatic cancer and leukaemia,” says Morten Lunde in its occupational health and safety discipline team. 

Norway’s occupational exposure limit for this gas was cut by 80 per cent in 2021, and a further 50 per cent reduction is expected within the next few years. That poses new demands for players in the petroleum sector. 

“The industry has taken the benzene challenge seriously, and many of the companies have good practices for handling it,” says Lunde. 

“However, we see that shielding against exposure is largely based on the use of PPE. That’s considered to be a weak barrier.”

Chemicals and cancer

Roughly three per cent of cancer cases in men, and 0.1 per cent among women, can be attributed in Norway to carcinogenic substances in the workplace. According to the World Health Organisation (WHO), cancer accounts for more than half the deaths related to occupational causes in western countries. 


At the same time, greater attention is being paid to diesel exhausts. Personnel exposed to these fumes report such complaints as nausea, dizziness and headaches.

“Findings from our audits indicate that a number of offshore facilities face challenges related to diesel exposure,” says Hilde Nilsen, who leads the PSA’s work in this area.

“We’ve also received several whistleblowing reports on it.” 

The industry has long lacked good measuring methods and clear cut-off points in this area. However,  a first occupational exposure limit for diesel exhaust – measured by elemental carbon – is due to come into effect on 21 February 2023. 

Lung cancer 

A blend of gases and particles, diesel exhaust fumes are classified as carcinogenic by the International Agency for Research on Cancer (IARC). Long-term exposure can increase the risk of chronic pulmonary disease and lung cancer.


These fumes derive from a number of sources, with main power generation on mobile facilities as a big contributor.  

Diesel-driven forklifts, cranes, fire pumps, emergency generators and various permanent or temporary generating sets may be highly significant at local level. And supply ship engines can also contribute. 

Technical measures to reduce exhaust gases, such as replacing diesels with electric drives or other engine types, or diverting fumes away from people, have already been widely adopted. 

Over time, electrification of both equipment and facilities is likely to make a positive contribution to reducing exhaust pollution. 

Photo of Hilde Nilsen
“Findings from our audits indicate that a number of offshore facilities face challenges related to diesel exposure,” says Hilde Nilsen, who leads the PSA’s work in this area. Photo: Emile Ashley


A collaboration project between the PSA and Stami was launched in 2022 to increase knowledge in the industry about exposure to diesel exhausts. 
Information has been acquired on challenges related to these fumes and company practice in managing the risk. Stami is responsible for collating these data.

They in turn will provide part of the basis for a report on the state of knowledge about diesel exhaust fumes in the petroleum sector. 

“We’ve previously known little about where and under what conditions the challenges have been greatest,” explains Nielsen. 

“The outline of a risk picture is visible, but more measurements are needed in order to better understand the level of fumes on offshore facilities and at plants on land.” 

Noting that the PSA sees the companies increasingly taking measurements, she emphasises that responsibility for mapping risk in this area rests with them. 

“They must keep abreast of learning and regulatory changes. The risk is largely managed today by direct readings of gas components in diesel exhaust fumes, which reduces control of exposure to elemental carbon. 

“No appropriate measuring equipment able to take direct readings of the latter is available at present. It’s important that the industry now collaborates to find a solution for integrated management of this type of risk.


National occupational exposure limits have been set in Norway for most chemical substances classified as carcinogenic. They specify a maximum level for the average concentration of a substance in the respiratory zone of a worker over an eight-hour period. In the offshore industry, these limits have been corrected for a longer working day. 

Lying as far as possible below the exposure limit should be an objective, since these levels do not distinguish clearly between safe and unsafe concentrations.  

Diesel exhaust fumes (measured as elemental carbon) 
Eight-hour exposure limit: 0.05 mg/m3 
12-hour exposure limit: 0.03 mg/m3

Eight-hour exposure limit: 0.2 ppm 
12-hour exposure limit: 0.12 ppm

Investigating exposure

The PSA has circulated a questionnaire to the whole industry aimed at identifying the risk to personnel of contact with carcinogenic chemicals and chemical compounds. 

Norway’s petroleum sector still uses such substances, including in maintenance, processing and production. Carcinogens can also be liberated during work operations and processes. 

“The companies were asked to answer questions on their use of chemicals,” explains Sølvi Sveen in the PSA’s occupational health and safety discipline team. 

“We also sought information on who’s exposed to these substances and under which conditions, and what measures have been taken to limit the health risk.” 

How many 

Company responses include details on how many carcinogenic chemicals they use. Most report a figure of around five, but a couple stand out with a substantially higher number. 

“That so many of the companies report low figures is an indication that processes aimed at eliminating carcinogens have had an effect,” says Sveen. 

“The industry has been working over many years to replace chemicals with alternatives which pose a lower risk to health. We’re seeing the results of that now.” 

Respondents to the survey also listed the three carcinogenic chemical products or compounds they used which are associated with the highest exposure risk. 

Benzene and diesel exhaust fumes recur frequently among the top three at all the companies, but such components as asbestos, welding fumes, alpha quartz and formaldehyde also appear. 

Most exposed 

This type of risk is unevenly distributed in the industry. The most exposed occupation groups include mechanics and personnel employed on technical cleaning. 

“The biggest challenge with the latter group is that it’s relatively small and comprises people who travel around doing the same job on several facilities,” explains Sveen. 

“It’s therefore particularly important that providers of this type of service ensure that overall exposure for the individual does not become excessive.” 

The regulations require employers to identify and assess risk related both to the use of carcinogenic chemicals and to jobs which could lead to the release of such substances. 

“On the basis of these assessments, they’re then required to take appropriate measures to remove or reduce this exposure,” Sveen emphasises. 
The results of the survey are summarised in a report published at