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Nitrogen oxide: Is it really that dangerous, lung doctors ask?

January 25, 2019

By Paul Homewood



h/t Tallbloke


German scientists are fighting back against mainstream thinking about the health dangers of nitrogen oxide and particulates.

From Deutsche Welle:



How dangerous arenitrogen oxides (NOx) and particulate matter really? Lung doctors have now joined the debate on driving bans in city centers, designed to enforce current pollutant limits. And they are by no means unanimous in their assessment.

First, the German Society for Pneumology and Respiratory Medicine (DGP) published a position paper on December 3, in which the authors point out the dangers of air pollutants. They list the effects of various pollutants on the lungs, heart, organ system, brain and on unborn children.

They insist that a "significant reduction in air pollution is required and a lowering of the legal limit values is necessary."  The authors call for a "culture of avoiding pollutants" combined with very concrete regulatory measures.

Epidemiological studies or rather toxicological experiments?

In principle, however, the authors point to a difficulty in the scientific definition of legal limits. As a rule, statisticians use epidemiological studies as a basis for recommendations to politicians. On this advice, the legislators then set applicable limit values.

However, epidemiology, which deals with the causes and spread of diseases within population groups based on statistics, has its limits: Since "mixtures of pollutants usually occur in road traffic, a purely epidemiological separation of the effects of individual components on the organism can be difficult or impossible," the authors of the position paper posit. In contrast, experimental toxicological studies on cells, animals or humans are more meaningful.

No agreement among lung doctors

A group of high-ranking pulmonary physicians has also criticized the inadequacy of epidemiological studies. They do not, however, share a central conclusion of the DGP position paper — namely that legal limits should be further reduced. To date, 112 German lung specialists have signed a document opposing the validity of current nitrogen oxide and particulate matter limits.

The pneumologist and intensive care physician Dieter Köhler is the initiator of the group and recruited supporters of his position within the medical profession at the beginning of 2019.

He published an article last September in the German medical journal "Ärzteblatt" denying the "scientific basis" of epidemiological studies, used to calculate the applicable pollution limits.

Coincidence or cause?

The core of his criticism is the confusion of causality and correlation by epidemiologists. In other words: In areas with high levels of particulate matter and NOx, people die on average somewhat earlier than elsewhere. But whether they also die fromparticulate matter and NOx is completely unclear.

It could also be due to other factors: smoking, alcohol consumption, lack of physical activity, lack of medical care, irregular use of medication and much more. "All these factors usually have a hundredfold stronger effect" than the increased risk from air pollutants, writes Köhler and his co-signatories.

Last but not least, the epidemiological studies completely ignore the question of a toxicological threshold dose for the respective air pollutant, the author posits, although "every poison, even the strongest, has a threshold dose."

Many victims of smoking, but where are the NOx deaths?

Should there actually be many causal deaths from particulate matter and NOx, then lung doctors should notice this in their daily practice, Köhler argues. But this is not the case at all.

Köhler cites an epidemiological study commissioned by Germany’s Federal Environment Agency (UBA) as an example. This study calculates additional deaths per year for NOx at 6,000 – 13,000 and for particulate matter at 60,000 – 80,000. That would be about as many people as dying a result of smoking.

"In their practices and clinics, pulmonary physicians see [deaths caused by cigarette smoke] on a daily basis; however, deaths caused by particulate matter and NOx, even after careful investigation, never," write the pulmonary physicians in their counterposition.

So it is "very likely" that the scientific data leading to these estimates "contains a systematic error." Apparently, they have been "interpreted extremely one-sidedly" and "always with the objective that particulate matter and NOx must be harmful," they write.

Appeal for a fair and open discussion

Köhler and his colleagues see their paper as helping to bring more objectivity to the emotional debate about driving bans, pollution limits and diesel exhaust gases. At least here they agree with the representatives of the established associations of pulmonary physicians.

The DGP, the Association of Pneumological Clinics (VPK), and the German Lung Foundation regard the publication "as an impetus for necessary research activities and a critical examination of the effects of nitrogen oxides and particulate matter," write the respective chairmen of the three associations


I have been making similar criticisms for a while.

Where are the death certificates showing pollution as a cause of death?

What about other factors, such as smoking, alcohol consumption, lack of physical activity, lack of medical care and irregular use of medication, which may unduly affect those same people who live in heavily polluted areas?

Hopefully this is the start of a proper and open debate about the issue.

  1. January 25, 2019 11:32 am

    Hopefully it will, but I’m not holding out much hope.

    • Adrian permalink
      January 25, 2019 2:30 pm

      You mean not holding your breath ?

      Actually I live just next door to some truly awful particulate polluters. I envy city folk with just the odd bus or truck.

      Trees drench the whole area in organic PM10-100s for much of the summer. These filthy things also support loads of scummy ectomycorrhizas that then just fill the air all autumn with yet more.

      Something has to be done, just because we’ve breathed particulates of this size through the whole of our evolutionary history doesn’t make it safe.

      I suspect the average pine tree produces more than my car. Time these witless pressure groups did something about it.

      I did read somewhere that the air quality in forests does fail various EU standards – does anyone know the reference?

      • jack broughton permalink
        January 25, 2019 3:23 pm

        Great comments, should we also make the people in Africa clear up the Sahara as we keep getting its dust. Sadly, this is part of the pseudo-ethics based claims from our BMA and The Lancet who are trying to tell us all what we should be doing irrespective of cost.

  2. January 25, 2019 11:38 am

    “Hopefully this is the start of a proper and open debate about the issue.” There are not many environmental issues where an open debate is allowed to occur.

    • Mike Jackson permalink
      January 25, 2019 2:31 pm

      No, Phillip, and we certainly won’t be allowed one in this context.

      “In areas with high levels of particulate matter and NOx, people die on average somewhat earlier than elsewhere. But whether they also die from particulate matter and NOx is completely unclear.
      It could also be due to other factors: smoking, alcohol consumption, lack of physical activity, lack of medical care, irregular use of medication and much more.”

      In other words Köhler is saying what the rest of us will never be permitted to say, namely that there are other contributory factors at work in the early death rate among the urban poor.

      “Good heavens, Michael! Are you suggesting that those who live in the slums drink too much, smoke too much, don’t eat properly, don’t take enough exercise, and then don’t look after themselves properly when they get sick?”

      “Er, yes, boss. Actually.”

      I shall report for re-education tomorrow.

      And for more inconvenient correlations — it is well established that the increase in childhood asthma has gone hand in hand with the decrease in air pollution over the last 60 years and that the increase in allergies has closely followed Mrs Suburban Housewife’s obsession with “hygiene” and “killing 99% of germs … DEAD,”

      I draw no conclusions, you understand!

  3. David Parker permalink
    January 25, 2019 12:06 pm

    As a result of lightning in storms Oxides of Nitrogen are produced. There are about 2200 thunderstorms occurring at anyone time. Who is going to stop them? Anyway NO2 returns to earth dissolved in water as a nitrogenous fertilizer FOC.

  4. bobn permalink
    January 25, 2019 12:22 pm

    It seems the theory goes that people living in cities, which have higher NOx and particulates in the air, die earlier than those in open countryside. Ergo, from correlation – blame NOx.
    However people living in cities for the last 2000yrs have always died earlier. London for over a 1000yrs has had a net loss of population (more deaths than births), that is only balanced by migration into the city.
    The biggest cause (ignoring knifings!) is disease. People in crowded places pass virus’s and bacteria to each other. (Take an aircraft flight and there’s about a 50% chance you’ll have a cold or something worse immediately after thanks to confinement in crowds).
    So living in a higher Nox environment (a city) means you’ll have more virus’s and illnesses over time and thus earlier deaths.
    Mystery solved.
    PS:Temperature has risen in the 20C at the same rate as sightings of UFOs. Ergo, from correlation, we can deduce its the aliens wot did it!

    • Harry Passfield permalink
      January 25, 2019 12:55 pm

      Good comment, BobN.
      This correlation is similar to the argument that ‘speed kills’ when, in fact, it’s only relevant in a very low proportion of accidents, let alone fatal ones.

      • Broadlands permalink
        January 25, 2019 1:21 pm

        ‘Speed kills’. We have been told that most automobile accidents happen close to home. The obvious solution is to drive a long way from home…quickly?

      • HotScot permalink
        January 26, 2019 10:43 am


        Speed doesn’t kill, stopping kills.

        Solution –

        Ban brakes.

  5. January 25, 2019 12:54 pm

    It seems as though more effort should be spent on the particulars than the particulates?

  6. Patsy Lacey permalink
    January 25, 2019 12:56 pm

    Ella Kissi Debrah aged 9 sadly died from an asthma attack in 2013. Air pollution levels monitored one mile from Ella’s home consistently exceeded EU limits in each of the three months before her death.
    Seemingly without any further examination into the causes of her asthma, a report from Steven Holgate a “leading expert in asthma and air pollution” stated that it was likely that unlawful levels of air pollution contributed to the asthma attack which killed her.
    The Attorney General has ordered a new inquest. The original inquest found she died from respiratory failure caused by a severe asthma attack.
    Not having any medical qualifications I would like it to be explained how the post mortem was able to establish degrees of causation

    • January 25, 2019 1:47 pm

      If the lawfare inclined activist lawyers are seeking to get an “Ella’sLaw” – they might want to target people who actually are unequivocally responsible for unnecessary mortality they might want to target NHS “executives”

      Facts and evidence huh ?

    • Gerry, England permalink
      January 27, 2019 10:19 am

      And yet with pollution levels at historic lows for our industrialised society – recall Paul posting the graph many times – they can’t explain the increase in asthma.

  7. January 25, 2019 1:13 pm

    It should be noted and not omitted, as DW does, that Prof. Koehler is former president of the DGP himself ( 2003-2007) So, he is not just a dissenting specialist, but one of the top dogs criticizing his successors.
    He particularly emphasized in his paper that there seems to be an overweight of ideology and a lack of scientific facts and research in the paper presented by the current board. He called for more “real” research without a predetermined outcome.
    He has been countered by attacks predominantly on a personal level, his achievements have been discredited and one opponent was not shy of calling him an “amateur”. ( Have a look at German Wikipedia).

  8. January 25, 2019 1:43 pm

    From my own anecdotal experience I am of the view that the main influence on these statistical results lies in those genes responsible for a deficiency in the enzymes necessary for the cleaning of the lung tissues.
    I say this as an 83 year old who has not only smoked throughout life but for some 30 years was in the shot blasting blasting, metal spraying and painting industry renowned for its production of noxious fumes, particles and metals so abhorred by the medical profession.
    I still have a relatively robust pair of lungs; however some of my in law relations have not been so lucky; this due, I gather to this enzyme deficiency.

  9. Mike H permalink
    January 25, 2019 2:00 pm

    Many European countries converted to diesel wholesale in the 70s-80s in response to oil crises. The diesels of those years were pretty filthy, as many of us can no doubt remember. If these pollutants are as toxic as claimed, it would be reasonable to see some hard evidence after 40-50 years of high exposure in the major conurbations of France and others.

  10. Joe Public permalink
    January 25, 2019 2:17 pm

    Pedant alert 😉 “Nitrogen oxide”:

    Oxides of Nitrogen (NOx)

    NOx is a collective term used to refer to two species of oxides of nitrogen: nitric oxide (NO) and nitrogen dioxide (NO2).

    [My italics]

    • Joe Public permalink
      January 25, 2019 2:18 pm

      Italics were supposed to apply to:

      nitric oxide

      nitrogen dioxide

    • A Man of No Rank permalink
      January 25, 2019 6:39 pm

      Funny that Joe. The third oxide of Nitrogen is N2O or nitrous oxide, wonder why that is not included. Used as laughing gas and can be toxic at high levels, does not try to choke you or blow your head off as NO2 does!

  11. Peter Shellis permalink
    January 25, 2019 2:45 pm

    Ross McKitrick wrote a review pointing out the inadequacies of the population studies on pollution and health ( Air Pollution, Health and Mortality: Separating Fact from Fiction). Given air pollution levels typical of the 60s and 70s, he showed that one model would atribute more than 100% of ALL deaths to pollution (!)

  12. dennisambler permalink
    January 25, 2019 2:53 pm

    In a post in 2017, Euan Mearns looked into the claim that 40,000 premature deaths were caused by diesel car pollution. In particular he examined a Channel 4 documentary:

    “Cars and trucks were shown with bright orange plumes of CO2 belching from their exhausts. Science editor Tom Clarke even breathed out to show the CO2 emanating from his lungs. CO2 was described as toxic. No mention was made of the fact that is is absolutely essential to all life on Earth. Throughout the program, the presenters seamlessly switched between CO2 and NOx as if they were the same thing.”

    It was a follow up to the Royal College of Physicians (RCP) Report – Every breath we take: the lifelong impact of air pollution – that was published in February 2016. Euan Mearns quotes from the report:

    “Air pollution plays a role in many of the major health challenges of our day, and has been linked to cancer, asthma, stroke and heart disease, diabetes, obesity, and changes linked to dementia. (Anything can of course be linked to anything else, simply by the phrases “scientists suggest, scientists think that, scientists say, scientists believe. It is a feature of epidemiological studies)

    Each year, inhaling particulates causes around 29,000 deaths in the UK, which, on recent evidence, may rise to around 40,000 deaths when also considering nitrogen dioxide exposure.” (Such precise numbers, with no evidence of even one death to such a cause).

    As Paul has pointed out, you will never see “cause of death, inhaling particulates”. These numbers are without substance but the “40,000 deaths” is now quoted as an unassailable fact. Numbers like this are what John Brignell at Numberwatch called Trojan Numbers:

    “One of the most effective forms of Trojan Number is the Virtual Body Count. Sub-editors cannot resist a headline Thousands to die of X.”

    The Mearns post is well worth a visit.

    Steve Molloy at Junkscience has a series of posts on PM 2.5 and the lack of evidence of toxicity:

    He has a whole lot more on Diesel, VW etc:

  13. January 25, 2019 6:07 pm

    Somewhat off topic:
    Nitric oxide is a molecule that’s produced naturally by your body, and it’s important for many aspects of your health. Its most important function is vasodilation, meaning it relaxes the inner muscles of the blood vessels, causing them to widen and increase circulation. Nitric oxide production is essential for overall health because it allows blood, nutrients and oxygen to travel to every part of your body effectively and efficiently. Nitric oxide production is essential for overall health because it allows blood, nutrients and oxygen to travel to every part of your body effectively and efficiently. In fact, a limited capacity to produce nitric oxide is associated with heart disease, diabetes and erectile dysfunction.
    5 Ways to Increase Nitric Oxide Naturally

  14. Vernon E permalink
    January 25, 2019 7:09 pm

    I remember in 1958 ‘ish at Manchester (university) evening after evening feeling my way along Cheetham Hill Road to my digs when I couldn’t see my own feet. I, and many other Mancunians, didn’t die soon after. No one defends the smogs form coal burning domestic fires but as Paul has demonstrated by real data that our air quality has improved year on year. Not to say that there aren’t hot spots that need to be addressed – there are. But let’s keep a sense of proportion.

  15. Dave Ward permalink
    January 25, 2019 9:53 pm

    “Speed kills”

    Another blanket statement used to justify all sorts of controls on us. At any given moment there are hundreds of thousands of people doing 500+ mph in pressurised aluminium tubes high above the earth. They aren’t dying in droves, and neither did the select few who used to hop across the Atlantic at Mach 2 when Concorde was still in service. It’s actually sudden deceleration which kills people. Not that any of the tax raising “Safety Camera Partnerships” would agree…

    • dave permalink
      January 26, 2019 12:33 pm

      The present breed of maniacs are called “experts” and “scientists.” But they are just fulfilling the age-old social function of throwing out devils and witches. The human race has a screw loose.

  16. jack broughton permalink
    January 26, 2019 2:56 pm

    The issue is not that we want to oppose cleaner and better environmental conditions, we need sensible approaches to the cost of improvement against the benefit provided. The BMA and many “experts & scientists” jump on one view and conclude that all wealth should go into their cause. As many people comment here, the atmosphere is far cleaner than in previous years. The UK has far better air-quality than most of Europe because of our prevailing winds, and much of our air pollution is from Europe.

    Sadly, the obsession with NOx and dust is diverting attention from the far more dangerous chemicals that are allowed to be released without restriction, but ought to be controlled urgently, such as antibiotics and many other chemicals that enter the sewage system, then recycle.

    • A Man of No Rank permalink
      January 26, 2019 8:08 pm

      On Jack’s point ” – the atmosphere is far cleaner than in previous years”
      In the early 1970s I would motor North up the M6, here in the UK, and the long hill before Keele service sation was always covered in a foul red-brown mist – these days its clear.
      I was at that time doing research on catalysts to take out NO2 from car exhausts. So the UK had its very own version of the famous LA red smog. At these high concentrations I could well believe that this was serious pollution.
      As someone who is impressed with the efficiency and social value of the internal combustion engine I have never believed that it can cause such carnage. NO2 is a strong smelling gas so even at miniscule concentrations I think we would smell it.
      Like the nerd that I am, I walk around our streets sniffing the exhausts of passing cars. Small amounts of unburnt hydrocarbons are always in the air, so too are partially combusted hydrocarbons but I rarely pick up the sharp vapour of NO2 – maybe twice a year.
      Like everyone here I await to read the detailed technical evidence of the Ella inquest.

  17. Paul H permalink
    January 27, 2019 12:17 am

    Downtown Singapore ’70-’72 was heavy with the smell of diesel exhaust fumes, I became hooked on it. Moving on, had a week in Hong Kong C. 2002 and was mystified at first at how clean the air smelled, until I realised most of the vehicles ran on LPG. Spending the next week in Singapore was in stark contrast, but then Singers has one of the worlds largest refineries offshore. Guess they have to support home industry.

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