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During a bright spell of cold, settled weather at the end of January, air in some parts of London became so polluted that the quality was worse than in the smog-filled Chinese capital Beijing. London mayor Sadiq Khan issued his first ever 鈥渧ery high鈥� pollution alert under a new monitoring system set up to warn of the dangers of what he described as 鈥渟hameful鈥� and 鈥渢oxic鈥� air.

Researchers estimate bad air causes a total of 9,500 additional deaths in the capital each year. No wonder, then, Khan has made the issue his 鈥渘umber one鈥� priority 鈥� above policing, transport and housing. And as part of that, he has the construction industry firmly in his sights. Because while you might assume the impact of construction activity to be small beer next to the millions of cars, buses and trains moving around the capital, it has a disproportionate part to play in the problem. The London Atmospheric Emissions Inventory (LAEI) estimates 12% of London鈥檚 damaging nitrogen oxide (NOx) emissions, 15% of large particulate matter emissions, known as PM10, and a smaller but still significant amount of the most dangerous fine particles, dubbed PM2.5, come from site-based plant and machinery.

Therefore Khan is now lobbying for new powers to charge developers for using all but the very cleanest and most modern plant, with punitive fines for those that don鈥檛 pay their bills. And while some may worry about the regulatory burden this puts on an already overstretched industry, the growing evidence around the health implications of breathing diesel-laden air is raising big questions about the impact this could be having on construction workers. So what is Khan planning, and should the industry already be doing more?

Thin air

This isn鈥檛 an issue that has come out of thin air. That inhalation of fumes and dust can have harmful impacts has long been known, even if the specific roles different polluters play is only now being understood. The LAEI shows construction鈥檚 role in this problem is less down to its most immediately obvious impact 鈥� the dust created by demolition, which causes just 1% of the capital鈥檚 PM10 鈥� than its fleet of site plant and machinery (known as non-road mobile machines, or NRMMs).

Pollution levels on sites are really very high indeed. Essentially, companies are poisoning their own staff

Daniel Marsh, King鈥檚 College London

This is down to the fact that because site plant doesn鈥檛 travel on public roads, its emissions are regulated under a different system to cars, buses and lorries 鈥� one that until now has been far more lax. Hence, according to a presentation by Colin Smith, transport certification manager at the Energy Saving Trust, a single modern excavator will push out 15 times the emissions of a modern double-decker bus 鈥� and that鈥檚 if it complies with the recent regulatory standards. Older plant will perform much worse. Daniel Marsh, senior air quality analyst at King鈥檚 College London (the institution that has done the most to understand the perils of filthy air), says: 鈥淭he construction sector lags far behind in terms of the non-road vehicles it uses. They鈥檙e big machines and they鈥檙e very dirty.鈥�

As far back as 2007, the representative body of London boroughs, London Councils, published best practice guidance around mitigating air pollution during development and construction. This formed the basic approach then adopted by the Greater London Authority when it drew up Supplementary Planning Guidance (SPG) to the London Plan, published in July 2014, setting out what it thought developers should do to mitigate on-site emissions.

The 2014 planning guidance set out the requirement to assess and devise a plan for likely emissions in the construction process as part of a planning permission. It also dovetailed with the creation of a new 鈥渦ltra low emission zone鈥� in the capital. Together, these stipulated certain minimum performance standards for NRMMs.

In doing so, London became the first jurisdiction to attempt to target polluting construction machinery.

Companies react

King鈥檚 College鈥檚 Marsh, who is a specialist in the contribution of construction sites to the air quality problem, says: 鈥淭his wasn鈥檛 popular with construction firms as it was going to cost them money. Plant hire firms don鈥檛 necessarily have great green credentials.鈥�

However, Kevin Minton, director at the Construction Plant-hire Association, says the body has had a good relationship with the GLA and has worked with it to make sure the GLA鈥檚 policy is practical. 鈥淲e鈥檝e been working with the GLA for many years on emissions policy, and we feel fairly confident that most equipment being put out by our members meets the standards required,鈥� he says. Under the SPG, boroughs are supposed to include the provisions in planning applications approved after September 2015, with tighter standards for central London and Canary Wharf, and all areas due to ramp up a notch in 2020.

Meanwhile, estimates of the scale of the problem have been going up year on year, making existing measures appear inadequate. Across the UK as a whole, pollution is estimated to be the cause of up to 40,000 deaths each year; across the EU that figure is 400,000. A major joint report by the Royal College of Physicians and the Royal College of Paediatrics and Child Health last year found that air pollution played a role in 鈥渕any of the major health challenges of our day鈥�, including cancer, asthma, strokes and heart disease, and had 鈥渆ffects on growth, intelligence, and development of the brain and co-ordination鈥�.

Crucially, its review of literature found that 鈥渘either the concentration limits set by government, nor the World Health Organization鈥檚 air quality guidelines, define levels of exposure that are entirely safe鈥�. Babies, the young, the old, those with existing health conditions and the poorest were found to be the most vulnerable to ill effects that were often permanent. Marsh says air pollution is also linked to reduced lung function, children having small lung sizes, early onset dementia and cardiovascular problems.

It was in this context the High Court last year quashed the government鈥檚 air quality plan for failing to bring the UK in line with legal pollution limits 鈥渁s soon as possible鈥�, ordering the government to develop a new strategy by this summer.

Estimated occupational cancer deaths by cause in Great Britain, 2005

Khan takes action

Given this mounting evidence, Khan has decided the existing regime for construction is too lax.

This is because it relies on London boroughs choosing to implement the SPG in their own policies, and then spending money to assess and enforce the provisions. With developer commitments to use up-to-date plant held in planning permissions, the only enforcement option boroughs have where these aren鈥檛 being honoured is to issue a stop notice on the development 鈥� something they are understandably likely to use only in the most extreme circumstances.

If people are exposed to diesel engine exhaust fumes regularly and over a long period, there is an increased risk of getting lung cancer

Paul Haxell, IOSH

So, Khan鈥檚 aim is to set up a kind of congestion charge for NRMMs 鈥� which developers can avoid by using the cleanest, most up-to-date plant. It would be done on the basis of self-registration, with fines for those who fail to pay. However, he would need new powers from government to bring this in, and is using the imperative provided by the legal requirement for a new air quality plan to make the case for these powers to Whitehall.

Officials say that while the level of charges and fines have not yet been determined, and will to some extent be dependent upon what powers are devolved, the aim will not be to generate revenue. A city hall source said: 鈥淲e鈥檒l set the charge levels after a huge amount of analysis at the price we think will get the right behavioural response. The principle is that we want to provide an incentive to switch to using new pieces of equipment.鈥�

The Construction Plant-hire Association鈥檚 Minton is not against these changes, and says the industry has so far been able to absorb the requirement for newer plant, largely through the usual fleet replacement cycles. However, he says the GLA will have to be careful not to set charges too high. 鈥淚f the level of fees were punitive it might deter organisations from voluntary compliance.

鈥淲e would humbly suggest that it鈥檚 better the industry can pay the charge than run the risk of unsafe working 鈥� we wouldn鈥檛 want someone to be fearful of using powered access because of the emissions issue and instead use a less safe ladder,鈥� he says.

Workers suffer

But while Khan is concerned about the impact on the health of all Londoners, and Minton the impact on the industry, others are more concerned about the impact of all this on the health of construction workers themselves. Data from the HSE 鈥� which hasn鈥檛 been updated since 2005 鈥� suggests 230 construction workers die each year from cancers related to exposure to diesel exhaust emissions 鈥� 6.5% of construction-related cancer deaths. Given recent advances in understanding the impact of emissions, though mitigated by improving vehicle emission standards, there are those who think the real impact could be much higher.

Marsh says: 鈥淲hile construction sites have the potential to raise pollution levels slightly for the surrounding neighbourhoods, what I鈥檓 finding is that pollution levels on sites themselves are really very high indeed. Essentially, companies are poisoning their own staff.鈥�

Paul Haxell, chair of the Construction Group of the Institution of Occupational Safety and Health, says diesel emissions are just one of the examples of the imbalance in how the industry addresses ill health compared with site safety, pointing out there are no legal diesel fume exposure limits. However, he does point to existing HSE guidance around how to manage diesel emissions. 鈥淏y managing the risk we can reduce the levels to which workers are exposed to diesel fumes,鈥� he says. 鈥淧ractical controls 鈥� could include consideration of switching to other forms of fuel, replacing old engines with newer versions and 鈥� good general ventilation in fixed or enclosed workplaces.鈥�

Not enough action

But Marsh, despite initiatives by some construction clients such as Crossrail, doesn鈥檛 think that enough is being done. He compares the current relative lack of action against the moment when the harmful effects of asbestos were discovered, and the industry changed practices almost overnight. While the causal relationship between emissions and death isn鈥檛 direct in the way it is between asbestos exposure and mesothelioma, Marsh says: 鈥淲e know what impact emissions have on death rates overall in the population. If you follow this piece of equipment round for 40 years in your job, it鈥檚 going to be you that it kills first. I think the industry should sit up and take a look.鈥�

For its part, the Health and Safety Executive said existing regulations on hazardous substances, known as COSHH, already required employers to implement adequate control measures, and that it wasn鈥檛 looking to update them. It added that employer guidance on the control of diesel engine exhaust emission (HSG187) had been in place since 1999. A spokesperson said: 鈥淭he technical principles upon which the guidance is based remain as robust as ever 鈥� There is some evidence that large construction companies use the latest clean technology.鈥�

So far, London is alone in taking action to tackle emissions from site plant 鈥� the so-called NRMMs 鈥� but as other cities implement low emission zones it seems likely others will follow the capital鈥檚 lead. Meanwhile, the evidence suggests it is high time the industry itself took a harder look at the issue.