Air pollution – a health issue and cars to blame right?

Four House of Commons Select Committees (The Environment Food and Rural Affairs, Environmental Audit, Health, and Transport Committees) have published their joint report on ‘Improving Air Quality’ – you can download it here.

The report concludes that ‘Air pollution cuts short an estimated 40,000 lives across the country each year, costing the UK an annual £20 billion.’ Amongst its many recommendations it states that Government must

  • Introduce a Clean Air Act to improve existing legislation and enshrine the right to clean air in UK law.
  • Bring forward the date by which manufacturers must end the sale of conventional petrol and diesel cars, in line with more ambitious commitments from around the world. Manufacturers of private, public and commercial vehicles should also take steps to reduce emissions from tyres and braking mechanisms, known as the ‘Oslo e ect’, which is also a signi cant contributor to poor air quality.
  • Require the automobile industry to contribute to a new clean air fund, following the ‘polluter pays’ principle, on a scale that adequately compensates for the health costs of diesel pollution.

Despite the terms of reference for the report investigating ‘how effectively do Government policies take into account the health and environmental impacts of poor air quality?’, the final report has been framed as exclusively a health issue with the wider environmental impacts being completely ignored.

This is therefore a partial narrative and a missed opportunity. I have previously reviewed the literature concerning the atmospheric nitrogen pollution in the uplands (see here and here) and have termed it the ‘elephant in the uplands’. Additionally I have also looked at the impact of low level ozone (which is formed in warm weather as a result of a reaction between NO2 and volatile organic compounds) – see here. The evidence that atmospheric pollution has detrimentally impacted on the vegetation of the uplands is compelling. This narrative explains the rise in extent and vigour of purple moor grass at the expense of heather especially in the light that heather beetle outbreaks have been and are widespread and destructive. Additionally, even in an era of reduced sheep numbers, heather shoots are vulnerable to selective grazing by sheep as nitrogen deposition has enhanced their nutritional value. I conclude that atmospheric pollution is a driver of change and not just an inconvenience.

Ozone is a well-known phytol-toxic gas and Ashmore (2005) provides a comprehensive overview of its significant adverse effects on human health, crop yields, forest growth and species composition and damage in semi-natural vegetation. For example, 1.2 million tonnes of lost wheat production in 2000 (which accounted for 7% of the total) was reported in the UK (RoTAP 2012 – see here).

The wider impacts of nitrogen deposition on nature conservation in the UK have been reviewed here and here and the wider impacts of ozone on nature conservation in the UK have been reviewed here.

Figure 1 on page 16 of the report is portrayed without the necessary accompanying warning.

With the exception of ammonia this graph shows that all emissions including nitrogen oxides are in sharp decline. However, despite the large falls in nitrogen emissions, the deposition of all nitrogen compounds has hardly fallen at all. This unexpected situation has arisen as the atmospheric chemistry over Britain has been altered leading to more rapid oxidisation of nitrogen. This rapidly oxidised nitrogen is deposited in the UK when previously it would have been exported to Continental Europe (RoTAP 2012 – see here). Low level ozone concentrations continue to rise.

Most interestingly a paper has just been published in Science Advances which concludes that agriculture is a major source of NOx pollution in California. The abstract of the paper (see here) concludes ‘

These approaches point to a large, overlooked NOx source from cropland soil, which is estimated to increase the NOx budget by 20 to 51%. These estimates are consistent with previous studies of point-scale measurements of NOx emissions from the soil. Our results highlight opportunities to limit NOx emissions from agriculture by investing in management practices that will bring co-benefits to the economy, ecosystems, and human health in rural areas of California.

I wonder if this research and the discovery of this overlooked sourced of NOx might explain why deposition levels in the UK are not dropping when emissions are. We could really do with some research on this matter in the UK.

The Select Committees report is good and if the recommendations are enacted progress will be made but it is a partial narrative and so only a partial solution. A range of measures are needed to ensure air quality improvements in rural areas too.

Ashmore M.R. (2005) Assessing the future global impacts of ozone on vegetation. Plant, Cell and Environment 28: 949-964.


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