Understanding Premature Deaths from NOx
We’re told we have a major health problem caused mainly by cars. We all know pollution is definitely a health issue, particularly in our cities. I’ve already written about the various sources of urban NOx and PM and have made the case that it’s factually inaccurate to blame poor air quality solely on passenger cars. But what should worry us all are the figures of premature deaths due to NOx pollution that are now firmly embedded in the media. We’re told that 40,000 people die in the UK prematurely because of NOx pollution. So where does that startling number figure come from and is it correct?
In 2015 the European Environment Agency report on Air Quality in Europe said that 72,000 premature deaths were attributable to PM and NOx exposure in 2012 across 40 European countries mainly because of exposure to diesel emissions. The EU called these figures ‘a public health emergency’. But if the EEA is right we should be seeing this massive death toll in our hospitals. This huge loss of life should be visible to everybody and we should be hearing about the extra strain put on the doctors, nurses and health services across Europe because of the thousands of these emission-related fatalities. But we’re not. And that’s why I wanted to look at those figures a little more closely.
The key word here is premature. A premature death is defined as one that ‘occurs before a person reaches an expected age. This expected age is typically the age of standard life expectancy for a country or gender.’ This means that every death before the standard life expectancy is a premature death whether it happens 20 years or two days before that life expectancy. Many of us die prematurely for a wide variety of reasons. All doctors and scientists realise that this premature death number has only a limited meaning so they’ve given us another more accurate value and its YLL – or ‘Years of Life Lost’. Years of Life Lost is defined as ‘The years or potential life lost owing to premature death and takes into account the age at which deaths occur giving greater weight to deaths at a younger age and lower weight to deaths at an older age.’ YLL therefore gives us more nuanced data than relying on the number of premature deaths alone.
In the EEA report they give us the YLL number for Europe as 800,000 years of life lost. That’s a terrifying figure.
But this number covers all of Europe - which is roughly 500 million people - and the EEA break this down to the number of Years of Life Lost per capita as 160 YLL/10 x5. That means 100,000 people together lose 160 years of life. For each person this works out as 0.0016 years or a more understandable 0.584 days - if an average life expectancy is 80 years or 29,200 days.
The EEA says that if the whole of Europe meets the EU proposed NOx limits of 40mg/m3 everywhere, we’d improve YLL by 205,000 across 500 million people or roughly - 3.5 hours.
To arrive at this time figure of premature loss of life of between half-a-day and 3.5 hours directly attributable to NOx pollution all I’ve done here is look at the tables in the EEA report and check the numbers. The 40,000 figure that’s now widely reported, broadly unquestioned, across the media is because of use of the word premature and if we’re not careful this misunderstanding of the actual facts of NOx pollution will cost us trillions in transport policy and legislation changes and improve our life expectancy by only a relatively tiny amount of time. We absolutely need to clean our air but we need to apply real numbers and real science to this debate. We’ve taken a badly phrased headline figure from an official report and allowed it to terrify millions of consumers. If we can’t even accurately understand the numbers what hope have we to really improve our air quality? Bad science won’t help us clean our air.
Lead Spokesman for FairFuelUK and TV Motoring Journalist and Broadcaster