Communicating the risks of particulate and chemical air pollution and air-borne radioactivity.

There is an interesting article “Cutting through the smog” by Nic Fleming in the 6th May 2017 New Scientist. There are some scare statistics given – “it is estimated to be behind 200,000 untimely deaths each year”. But, as the author points out quantifying the impact of air pollution is a more complicated and uncertain business than the headlines admit.

There are parallels with the issues of environmental radioactivity and distrust of the nuclear industry.

Air pollution and radioactivity do not kill in the same way as being hit by a London bus might. Air pollution may aggravate other problems you have and has been linked to respiratory and pulmonary diseases and stroke. A UK committee has estimated that the anthropogenic PM2.5 released at 2008 levels would shorten the average person’s life by six months. This is morphed into costing 29,000 deaths a year in the UK, which is the major headline carried by the media.

Similarly radiation, in low doses, does not lead to instantly noticeable effects but rather is suspected of leading to an increase in the incidence of cancer in later years. Quantifying the additional cancer risks posed by different types of radiation at different doses, different dose rates and on people with different inherent cancer risks is complex and usually, by necessity, over simplified when attempting to explain it to the public. ICRP states that the linear no-threshold hypothesis “remains a prudent basis for radiation protection at low doses and low dose rates” but there is also an increasingly strong insistence that there is some kind of a threshold at 100 mSv. (See IAEA EPR Communicate).

In the UK it is the local authorities that are tasked with implementation of the national air quality strategy. The Lancet  fears that this will lead to a fragmented approach “as hundreds of local authorities (tasked with implementation) attempt to follow central government guidelines” and they doubt the “the ability of the government to measure progress and hold failing local authorities to account”.

Unfortunately the steps taken to reduce air pollution, particularly in cities, have always struggled to keep up with increased road usage and, particularly, increased use of diesel engines. The New Scientist report questions the effectiveness of the London Low Emission in reducing levels of pollutants or related respiratory and allergy problems in children despite its wide scope. Encouraging more people to walk or cycle and providing low emission public transport would seem to have just reduced the rate of increase of vehicle mileage in cities. Well worth doing but not enough. It is noted in the article that emissions of a number of key pollutants in the UK are dropping, for some quite dramatically. But more progress is desired.

The report claims that face masks vary from about 80% to 30% effectiveness at filtering particles from the air but it depends on the nature of the mask, the nature of the pollution and, importantly, the quality of the fit to the face of the mask. Unless they are treated with appropriate chemicals the masks have no impact on gaseous pollutants such as NO2 and SO2. Face masks are not recommended in the UK as an effective countermeasure against inhaled radioactivity in the event of a reactor accident because of concerns about their effectiveness without face fitting and training and because the principle component of concern are the radioactive iodine species. The preferred approach is to remove the person from the threat by sheltering or evacuation. For a non-technical discussion about face masks see an article by the survival mom and the comments attached to it.

A difference between air pollution and environmental radioactivity is that the public do not seem to fear air pollution to quite the same extent. Shunichi Yamashita reflects on the situation around Chernobyl and Fukushima following the two severe accidents in those places in the New Scientist of 13 May 2017. He reports that the big surge in non-thyroid cancers and genetic effects in the areas affected by Chernobyl that some predicted have not been detected. His advice to people in Fukushima in the early aftermath of the accident there, which was to try to relax and to try not to worry about the enhanced environmental radioactivity, was widely condemned but he still contends that he would expect no apparent health effects when the exposure was below 100 millisieverts a year. (I’m not sure about the “a year” bit, it might be a misunderstanding. ICRP advice is that a one-off residual dose of 100 mSv is probably not harmful but that the dose-rate thereafter should be no more than 20 mSv a year. (See ICRP letter to Fukushima residents).

The article concludes that psychological effects from the trauma of evacuation and the fear of radiation are now the biggest health consequences of the nuclear accident at Fukushima. Adults are experiencing depression, sleep loss and anxiety. There have been more than 80 suicides linked to the accident to add to the 60 people who died due to poor medical support during the evacuation. But there have been no deaths or sickness from direct exposure to radiation.

The conclusion from comparing the articles on air quality and post-Fukushima health concerns is that understanding the impact of airborne pollutants including ozone, particulates, NOx and SOx and radioactivity is very difficult. Communicating those potential impacts to the public is also very difficult but also very important. Without an understanding of the relative impacts of different aspects of modern life it is not possible for the public to understand the absolute and relative risks posed or for governments to sensibly prioritise policy and funding.