Last year the press reported that flossing your teeth is not really that helpful and can – if not done properly – be even counter productive. They also mentioned that brushing your teeth for more than 2 minutes doesn’t bring any additional benefit.

Is it possible that with asbestos in building materials there is also a point where additional remedial measures don’t produce any more positive effect, or even cause more harm than benefit?

Last year, the Swiss authority in charge of occupational health protection, SUVA, published a guideline on the deconstruction of buildings with asbestos in paint, plaster or tile mortar.

Before this guideline was published, these materials needed to be removed prior to demolition. This was done in a de-pressurised zone which usually required a scaffolding. Such a project could last for days and days if not weeks. Even though workers had to wear full protective equipment, they were exposed to a limited amount of asbestos fibres (no respiratory mask is 100% airtight) and the risk of “conventional” accidents when working on a scaffolding isn’t insignificant either (eventually even bigger than the risk linked to asbestos in this particular case).

According to the new guideline, such buildings can be demolished with a excavator without prior asbestos removal. A worker has to permanently wet the walls and he as well as the excavator operator need to wear light protective equipment (FFP3-mask and disposable protective suit).

This method has many advantages over the conventional method: The duration of the work and thus of the asbestos exposure of the workers is shortened. The risk of “conventional” accidents (in particular linked to working on a scaffolding) is lowered too. And of course this allows to massively reduce the cost.

But what about the environmental impact? How many fibres do the neighbours breath? What happens to the dust that covers the soil? And the water that is used to reduce dust? And can we still recycle the demolition rubble?

As the SUVA has no authority on these fields, they simple state that in addition to their ok, such projects need to be approved also by the local authorities in charge of public health and environmental protection.

At present only few local authorities permit such procedures even though various measures of asbestos fibres in the air have shown levels way beyond the legal limit. The main argument is that the uncertainties about the level of contamination of the air, the soil and the water are still high.

The debate about this method has caught up again after the publication of a study of the overall environmental impact (live cycle assessment) of various asbestos removal methods. The study, mandated by the Swiss Canton of Zurich (itself owner of various buildings) compares the overall health impact (measured on one hand in DALY, Disability-Adjusted Life Years) and environmental impact (eco-points according to the Ecological Scarcity Method). In addition to the workers’ health, the study thus includes data on the grey energy (fuel/electricity consumption of the removal work and transportation), the impact of the disposal as well as public health in general.

This study comes to the conclusion that complete removal of asbestos in plaster and tile mortar before demolition of a building has indeed a worse environmental and public health impact than if the building is demolished as proposed by the SUVA. (Note that this does not apply to renovation of buildings).

Before we come to the conclusion, it important to understand the scale of this problem: At present, we assume that roughly 10 to 15%, maybe up to 20% of all buildings in Switzerland contain paint or plaster with asbestos. We are speaking of an asbestos content that is usually below 1%, but this still brings us to tons of pure asbestos. The financial cost of removing these materials prior to demolition is of several billion of Dollars over all of Switzerland.

Given the scale of the problem, it is understandable that the authorities are hesitant to allow the demolition without prior asbestos removal. But simply insisting on asbestos removal prior to demolition of such buildings isn’t an option either, considering that the overall environmental and health impact may even be negative. In short: We need to collect and evaluate more data and studies on topics like: Long term behaviour of asbestos in the air (sedimentation of airborne asbestos fibres) asbestos in soil, and asbestos fibres in waste water.

One final note: It is important to understand that asbestos in paint/plaster on walls is of no danger for the public in itself. The problem arises when it’s removed. Compared to other asbestos containing materials, in particular spray asbestos, the exposure levels when not properly disposed of remain lower by a factor between 1000 to one million or even more. A debate like we currently have it around Glyphosate is thus not justified.