Dust impact on observatory stops quarry extension

Mhardcastle

Dust and noise - two of the main impacts people think of in relation to quarrying. And while noise is a nuisance, dust can be a killer.

Small particles are a particular problem. They can travel large distances and can be damaging to human health even in low concentrations over prolonged periods of time. Terms PM10 and PM2.5 are used to describe particulate matter of 10μm and 2.5μm in size respectively (a human hair is about 50μm in diameter). A quarry can generate significant amounts of this harmful dust over its lifetime, particularly during dry conditions. We’ve written about this dust - Respirable Crystalline Silica - before. HSE advice is that "all RCS is hazardous", and that workers should be told that "very fine quarry dust can cause silicosis, which leads to disablement and early death". The US Health Department warns "Residents near quarries and sand and gravel operations potentially are exposed to respirable crystalline silica". One study concludes "there seems to be a risk also in groups exposed to lower levels [of respirable quartz]. There is no consensus how low an acceptable risk level ought to be".

Keeping these facts in mind, it’s interesting to note that plans for a sand and gravel quarry extension in Hertfordshire were recently refused on appeal - because of this PM2.5-PM10 dust. Perversely, and despite objectors' fears, not because the planning inspector was concerned about the impact of prolonged exposure to this airborne carcinogenic dust on people living as close as 75m away, but because he was concerned about the impact the dust might have on an observatory - 550m away.

The quarry company had put forward a Dust and Air Quality Management Plan (DMP) which claimed to “proactively” manage the dust. Objectors, however, had little confidence in these measures, and nor did the University of Hertfordshire’s Bayfordbury Observatory, who were "...concerned about the potential for a significant loading in PM dust in the air for significant periods of time".

The Inspector was also unconvinced the DMP would work:

I am also concerned about its effectiveness in limiting harmful concentrations of PM2.5-PM10 dust, given their long suspension in the air and ensuing unpredictability and that monitoring and any preventative action would need to be the subject of constant surveillance... Responding to visible signs of dust emissions in dry, windy conditions would plainly not be effective as a preventative measure… For all that the DMP would provide for an enhanced level of control over dust emissions, given the risks and uncertainties that I have outlined above, I cannot be confident that it would prove to be fully effective... I conclude that the proposal would give rise to an unacceptable risk of harm to the operation of research equipment at the observatory, having regard to dust.

But when the planning inspector recognised the "long suspension in the air and ensuing unpredictability” of PM2.5-PM10 dust, and the harm such dust might cause an observatory 550m away, why did he not think that over prolonged periods it might be harmful to people too, living just 75m away? Were his hands tied by planning guidance? Did he put too much faith in consultants' reports? The observatory may have been particularly sensitive to dust, but so too are children, asthmatics, allergy sufferers and the elderly.

Whatever his reason, he refused the appeal anyway, and people nearby were spared prolonged and elevated dust emissions; others across the country continue to suffer. 

Since PM2.5-PM10 dust can travel long distances, planning authorities should be pushing quarry companies to act in a more precautionary manner, pushing for greater stand-offs from nearby communities, pushing for more rigorous dust mitigation. As DCC's Sustainability Appraisal warns, "due to a changing climate there is the potential for the impact of noise and dust on sensitive receptors to become more intense. Hotter summers will provide conditions that will produce additional dust, and people will spend more time outdoors and leave the windows of dwellings and workplaces open for longer". Planners' attitude to dust and the harm it can cause has to change.

PS. On the subject of consultants' reports, prepared for and paid for by quarry companies, and how much trust can be placed upon them, it may come as no surprise that the Dust Impact Assessment for the above quarry extension claimed "any impact associated with dust generation upon the observatory is considered to be low". The Planning Inspector, on the other hand, said "given the apparent importance attached to the observatory’s research activities, any harm arising from operations, notably in relation to PM10 dust, must, I conclude, have the potential to be severe". Low or severe? They can't both be right.