Fresh air – the growing battle to end airborne pollution

Fresh air – the growing battle to end airborne pollution

The war on air pollution is intensifying – partly because air quality is deteriorating, but also because we now know much more about its dangerous chemistry and negative health impacts. I would like to explain why asking key air quality questions at the start of all new projects has become essential.

The last two decades have seen tremendous changes in our understanding of air quality issues. When I began my career at the end of the last millennium, it was generally thought that outstanding air pollution problems – particularly at exposed roadside locations – would be resolved by now.

Sadly, the opposite is true. Polluted air is a potentially long-term lethal threat that cannot be solved by goodwill and chance alone. Which is why we are here to help.

Clearing the air

In a moment, I want to outline the problems and how they are being tackled, explain why Enzygo has turned a Cinderella environmental issue into a proactive solution strategy, and then quickly review some other important changes.

Later, I will also look briefly at the composition of pollution, which forms are the most dangerous, the many human health risks that poor air poses, and how modern answers are evolving.

Tempus fugit!

More than twenty years on, I am privileged to lead Enzygo’s expanding air quality team ( and its fundamentally different approach to air quality designed to bring a triple-set of benefits to a worsening situation.

We help developers to meet increasingly tough and complex rafts of new national and local regulations. At the same time, we optimise solutions before bad assumptions get baked in. But crucially, we are also here to help avoid expensive future retrofits. In other words, no nasty surprises!

However, our core message is that emissions must be considered at the earliest design stage of investment and infrastructure projects … not as bolt-on solutions after hard-to-reverse decisions have been taken.

Making bad air days history

Making bad air days history

The pea-soup smogs (smoke and fog) of the 1950s and 1960s have long gone.

But what was acceptable until a much later date we now know from detailed health studies can still be a primary cause of poor health problems, particularly for people exposed over long periods. Only quite recently did a coroner’s report make the first ruling of air pollution as a direct cause of death!

As science and public perceptions have moved forward, the onus has grown on developers to do much more to mitigate the impacts of their additional emissions to protect people using or affected by development land and ensure ecosystems are not damaged.

Statutory obligations are also forcing local authorities to produce air quality action plans in identified areas that are often notorious pollution trouble spots from a concerned community perspective.

Supplementary planning documentation is being introduced by some authorities as part of a general tightening of planning policies closing around developers.

Technology is a further factor. Advances in low-emissions technology must be integrated into astute project planning. In London, for example, after a decade of pushing for Combined Heat and Power plants, the new preference is ground source heat pumps.

Air quality ‘neutral’ and ‘positive’

I think this is a good point to look at what different authorities now expect. The factors above show the direction of travel, plus the kind of standards and provisions developers must be ready to meet.

The basic concept is an increasing requirement for developments to prove that their air quality impacts are offset – or ‘air quality neutral’. However, there is currently a major fork here that is splitting the road into two routes – both accounted for in our advanced approach.

Firstly, a number of local authorities are issuing supplementary planning guidance which asks for a monetary estimate of the costs of additional pollution linked to new developments.

Two examples are the ‘West Yorkshire Low Emission Strategy’ ( and KentAir’s ‘Air Quality Planning Guidance (

In both cases, the documents give advice on the types of mitigation expected for different scales of development. They also indicate the amount of money to be put aside to meet these measures. Obviously, our aim is to keep costs as effective and reasonable as possible.

London Calling

London calling…

But secondly, London’s ‘air quality neutral’ approach differs and seems to be more real world planning friendly.

It considers mitigation needs by comparing a development’s own transport and building emissions against ‘suitable’ emission benchmarks related to its scale (

Different benefits and flaws

Whatever system is used, it is no easy task to meet national policy requirements by trying to estimate and equate mitigation needs against impacts. Both of the approaches above have flaws.

The cost method may be well meaning but assumes a development’s maximum gross impact. This may lead to excessively high costs that could result in good schemes being derailed or stopped.

Meanwhile, London’s benchmark approach only considers emissions from cars. This can leave a sizeable emissions window for heavy vehicles that have much larger local impacts.

The approach adopted by London and other major cities can also be unsuitable for provincial settings because of factors like public transport availability, scale and energy/heating options such as the transition to low-carbon ground source heat pumps.

‘Air quality positive’

Moving forward, London’s anticipated ‘air quality positive’ guidance is still in consultation. But, with reference to one outcome of the New London Plan, it is expected to promote a holistic and mainstreaming design approach whereby developments must show how all design aspects that could affect air quality impacts, exposure and urban geography are considered in the design.


This is where Enzygo’s active focus not just on compliance but also on proactive design has been carefully orientated to the future ((

Our air quality team looks at the impacts of existing airborne pollution on site users in areas of poor air quality and odours. We also consider what effects additional emissions from new developments will have on human health and ecologically-important sites in surrounding areas.

The next step is usually to offer initial advice on local requirements, followed by likely mitigation needs, plus a great deal of practical detail on potential development impacts and their implications.

As a very simple practical example here, we might question if balconies will encourage pollutants to enter indoor areas, or whether electric vehicles charging points have been considered.

Once the design is fixed, we like to have complete information on potential emissions to model and assess all their impacts in detail before offering advice on a full range of options and alternatives.

Because Enzygo’s specialists cover a comprehensive range of overlapping environmental disciplines, our experience, track record and reputation are often pivotal in gaining planning permission from relevant local authorities for solutions that are most favourable to our clients.

Wider Issues

Wider issues

I promised to mention some of the mainstream and background studies, reports and findings that are helping to reshape and more closely define air quality best practice.

Fortunately for me, they reinforce many of the points I make above and include recent research which shows that even small rises in pollution exposure can lead to an increase in the severity of mental illness.

A British Journal of Psychiatry survey of 13,000 people in London found, for example, that small nitrogen dioxide increases resulted in a 32% rise in risk for community-based treatment, plus 18% more hospital admissions. The implication is that there are no safe limits. (

Depression and anxiety are common symptoms; there is also a marked increases in suicides. The researchers add that the annual financial impact on the NHS is ‘tens of millions of pounds’. ‘Huge’ reductions in intelligence linked to dementia are also cited, as is ‘damage to every organ in the human body’.

The World Bank estimates air pollution costs the global economy $5 trillion annually ( in heart and lung damage alone.

Further research ( suggests that air pollution is taking up to six years off the lives of billions of people globally and is now a far greater risk than smoking, car accidents or HIV/Aids. On average, it says, global citizens lose 2.2 years of life to air pollution – adding up to 17 billion avoidably lost years!

What is air pollution?

Finally, I would like to talk quickly about three points that are central to everything I have said above but haven’t explained in detail – the definition of air pollution; catastrophic health impacts; and legislation.

Pollutants with the highest health impacts are particulate matter (PM), nitrogen dioxide (NO2) and polycyclic aromatic hydrocarbons (PAHs) created by the incomplete combustion of gasoline and diesel fuel. Other components include ozone, sulphur dioxide, ammonia and carbon monoxide.

Main PM sources are diesel and petrol engines, solid-fuel (coal, lignite, heavy oil and biomass) household gas, industrial (building, mining and manufacturing), vehicle tyre and brake wear, plus road surface abrasion.

PMs are formed from sulphates, nitrates, ammonia, sodium chloride, black carbon, mineral dust and water. The fine diesel and petrol particles also absorb on their surfaces volatile organics and poly aromatic hydrocarbons.

PMs are classified by size; the main categories used are PM10 (particles less than or equal to 10 microns (µ) in diameter), and PM2.5 (particles less than or equal to 2.5µ in diameter).

Particles of 2.5µ or less cause are thought to cause most harm. Those between 10 and 2.5µ can lodge deep inside the lungs; PM2.5 particles penetrate lung barriers and enter the blood stream.

Health Impacts

Health impacts

Air pollution can cause asthma, chronic obstructive pulmonary diseases, impaired lung function, lung cancer, heart attacks and stroke.

Children and adults with pre-existing asthmatic and respiratory conditions plus a high risk of cardio and cerebrovascular diseases, are at increased risk from infection, sensitivity to allergens, arrhythmia, ischemia, cardiac failure and stroke.

Public Health England (PHE) says air pollution may cause up to 36,000 early deaths annually in the UK (; some sources suggest 40,000.

Air Quality Standards Regulations 2010

The EU Ambient Air Quality Directive (2008/50/EC) originally set binding limits and target values for major air pollutant concentrations and was transposed into the UK through the Air Quality Standards Regulations 2010.

The directive includes limit values for NO2, PM10 and PM2.5, sulphur dioxide (SO2), polycyclic aromatic hydrocarbons and ozone. The World Health Organisation (WHO) has guidelines for limit values for NO2, SO2 and ozone, plus PM10 and PM2.5 using gravimetric measurement.

To reflect how the forthcoming Environment Bill (which is expected to finish its passage through Parliament in winter 2021/22) will affect air quality, the Government has released the ‘September 2021: Air quality factsheet (part 4)’ policy paper (

A number of areas in the UK exceed these critical limits, particularly for NO2. Which is one reason why we are here to help.

My key message must be that it is important to involve experienced air quality professionals as early as possible while new proposals are being discussed.

If more information on any of the topics above would be helpful, or if you would like to discuss specific projects in confidence, please feel free to contact me at any time.

Conal Kearney – Director of Air Quality – Enzygo Ltd

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