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Design Green Architecture
Another reason to avoid concrete: silica dust ... Contractors are having trouble meeting the new safety standard.
Public Domain Concrete demolition via PXhere
Contractors are having trouble meeting the new safety standard.
The concrete industry likes to say that concrete is recyclable at the end of its life, although almost 80 percent of recycled concrete ends up as fill and road bases. But there is another problem; as the UK concrete centre notes, it is strong stuff that lasts a long time.
It is more than likely that a modern concrete building will come to the end of its useful life because no further use can be found for it, rather than because the concrete failed due to age.
It's hard work, taking it apart with big machines and jackhammers, and it creates a lot of silica dust. A new study has found that levels at demolition and crushing sites were way above the legal limits. According to Safety and Health Magazine,
Workers performing concrete chipping at substructure bridge repair sites had the highest level of respirable crystalline silica exposure, a time-weighted average of 527 micrograms per cubic meter of air. That is more than 10 times the PEL of 50 micrograms per cubic meter that OSHA established in its most recent silica regulation (1926.1153).
According to Silica Safe, inhaling crystalline silica 'can lead to serious, sometimes fatal illnesses including silicosis, lung cancer, tuberculosis (in those with silicosis), and chronic obstructive pulmonary disease (COPD).' There are between 3,600 to 7,300 new cases of silicosis in the USA each year.
Silica dust can be controlled with water, and workers can wear respirators and other protective gear. Silica Safe also recommends that workers change their clothes before bringing them home, showering before leaving the job site, and 'parking your car where it will not be contaminated with silica.' I have never heard of anyone ever doing this.
Silica dust gets into the air during construction as well as demolition, with grinding, drilling and other activities that come with concrete. Perhaps this is another good reason to use less of the stuff.
February 14, 2019
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