Formaldehyde exposure patterns in a set of Italian indoor workplaces with and without specific emission sources - 2011-2018




formaldehyde, occupational exposure, passive sampling, risk assessment, risk control strategies


Formaldehyde is a ubiquitous carcinogen causing widespread exposures, both occupational and non- occupational.

In order to prevent both short-term and long-term adverse health effects (cancer included), different guideline values and limit values for indoor formaldehyde vapours concentration have been proposed.

There is a widespread debate about the existence of a threshold exposure value for the arising of carcinogenic effects of formaldehyde, impacting on the significance of the proposed limit values(health-based vs. risk-based).

Specific criticalities arise when specific emission sources are present inside a workplace and it is necessary to distinguish background from more significant exposure levels, establishing strategies for a proper management of the so-called “low†occupational exposures.

The aim of this paper sets not about the discussion about safe vs. not-safe exposure levels, but about the necessity to distinguish scenarios of background vs. significant (“qualifiedâ€) occupational indoor exposures to formaldehyde. Specific preventive and protective actions are requested in the latter case.

The paper presents the patterns of formaldehyde vapours’ concentration measured in a set of indoor Italian workplaces with and without specific emission sources, discusses a pragmatic cut-off value of 35 μg m-3 for long exposures in order to identify significant (“qualifiedâ€) occupational exposures and proposes clues about the efficacy of distinct exposure management approaches.

Over the 2011 – 2018 period, a sequence of 117 passive diffusive indoor samplings was performed: 26 samplings (all environmental) lasting 1 hour or longer in workplaces without specific sources of formaldehyde, 75 samplings (69 environmental, 6 personal) lasting 1 hour or longer in workplaces with specific sources of the agent, and 16 samplings (5 environmental, 11 personal) lasting less than 1 hour in workplaces with specific sources of the agent.

In the data analysis, the samplings were grouped according to duration, i.e. more than 1 hour (“long samplingsâ€) and less than 1 hour (“short samplingsâ€).

The mean formaldehyde levels determined from environmental long samplings in workplaces with and without specific emission sources (plastics moulding factories, foundries, abrasive disksmanufacturingplants, a women’s hairdressing salon, a surgical block where formalin was used for tissue fixation, a hospital Histopathology unit vs. an office, a medical practice, a waiting room, a reception hall, a sterilization room were no formaldehyde-based product was in use, and a conference hall) were 16.6μg m-3 and 12.2 μg m-3 respectively. Both groups of values are, as a whole, low and very close between them, clearly as a result of more or less effective industrial hygiene measures (enclosure of emission points, local exhausts aspiration, general ventilation) where specific sources are present.

However, personal long samplings in a subset of the aforesaid workplaces with occupational exposure to formaldehyde showed a mean value of exposure of 34.8 μg m-3.

In general, personal samplings, both longer and shorter than one hour, showed formaldehyde levels higher than the corresponding environmental ones: twice higher in the above mentioned women’s hairdressing salon (43.1 μg m-3 vs 21.9 μg m-3), more than four times higher in three farms and a mortuary (the mean values from short and long samplings were found to be 512.3μg m-3 and 122.2 μg m-3 respectively).

These results highlight the need to pay attention to all aspects of the workers’ activities involving any condition of close proximity to the emission sources which increase individual exposure.

A growing pattern of mean formaldehyde levels emerged, from 12.2μg m-3 (long samplings, no specific sources) up to 512.3μg m-3 (short samplings, presence of specific sources).

In the workplaces with no specific formaldehyde sources (all environmental long samplings), the level of 30 μg m-3 was never exceeded, with the only exception (31 μg m-3) of an office where the sampler had been located very close to a sporadically used laser printer.

Only a subset of long samplings taken in workplaces with specific formaldehyde sources showed levels exceeding 30 μg m-3, up to 75 μg m-3: these were strictly related to the inadequacy of emission point enclosures, to faulty local exhaust aspiration and to poor general ventilation.

Top values largely exceeding 100 μg m-3 were observed in short samplings from the three above mentioned farms (where the problem was quickly worked out each time by replacing all formaldehyde-based products) and from the mortuary (a setting where the use of formaldehyde-free products for corpse preservation is not an established routine yet).

Theseresults support the feasibility of adopting conventional, pragmatic cut-off values for indoor formaldehyde levels, in order to conventionally distinguish between background and significant (“qualifiedâ€) occupational exposures in presence of specific emission sources of the agent.


Author Biographies

Roberto Calisti, ASUR MARCHE

SPreSAL Epi Occ director

Lucia Isolani, ASUR MARCHE

SPreSAL Epi Occ MD

Rossano Mei, ASUR MARCHE



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