Biomass, wood smoke, particulates and cancers

When we breathe in we inhale not only air but dust, and very small particles of stuff that we humans have put in the atmosphere. We know that these can be harmful – coal dust and asbestos dust spring immediately to mind.

Because we are putting relatively speaking so much into the atmosphere scientists are trying to understand the effect of these particles on human health.There is therefore a great deal of study and experimentation involving the toxicology of particles and fibres.

Much of this is reported in Particle and Fibre Toxicology, which you can access at http://www.particleandfibretoxicology.com/ . The journal is peer reviewed and attracts papers from scientists of many different disciplines, in order to encourage the inter-disciplinary approach that is necessary in this field, and indeed in most fields of human study.

Climate change scientists examine global phenomena using physics, chemistry, geology climatology, meteorology, and many other disciplines. Particle toxicologists examine the reactions of tiny substances in small quantities on animals using physics, chemistry, physiology, biology. Sometimes you ignore the small things at your peril.

Climate change is a big thing, unable to be verified by experimentation and subject to much discussion and many alternate theories even though a scientific consensus has been reached which would be dangerous to ignore.Particle toxicology involves tiny substances, which you also ignore at your peril.I have written from time to time about biomass – wood burning to generate energy – either heat energy for homes or in the case of the propose Port Talbot Power Plant electrical energy.

Biomass is promoted as a carbon free or low carbon way to generate energy, because the plant material is replaced and the carbon emitted is reabsorbed. I have expressed my doubts about this being wholly true.There are health issues with burning biomass, and as a society we seem to be a little blind to them.

We woke up to health issues with coal mining and asbestos rather late in the day and I would hope we can avoid this happening with biomass.

Some studies were carried out in Norway where the main air pollutants are caused by vehicles and wood burning which together are responsible for 65% of Norway’s total emissions. The scientists wanted to try to understand how the content of particles, their size and characteristics affect human health and find physical or chemical properties of these particles.

Now particles from asbestos, cigarette smoke and similar matters have been associated with health problems – particularly cancers and heart disease, although the precise way in which they cause these problems is not fully understood.The scientists tested a traditional wood burning stove by burning wood in it at high temperature and collecting and analysing the smoke and also by collecting exhaust fumes.

These studies have been reported in the Particle and Fibre Toxicology Journal. The scientists found that the exhaust particles were smaller than the wood particles but that the wood smoke particles had a higher polycyclic aromatic hydrocarbon (“PAH”) content.

Some studies link particles with a high PAH content to these health problems and that there is a strong relationship between organic particles (such as cigarette and wood smoke) to lung cancer. One particular type of PAH has been identified by the US Environmental Protection Agency as a cause for concern – PAH 16 which is thought to be carcinogenic.

Because they found that the PAH content was much higher in wood smoke than in vehicle exhaust, they concluded that it was important to understand more about how the body responds to higher PAH content in particulates, rather than compare wood smoke and traffic fumes.

There are still many questions that need further research – what is the precise role of inhaled PAHs on human health? Does using different wood sources affect the PAH content? Does using reclaimed, painted or varnished wood provide a higher or lower PAH content when burnt?

The message here is not that wood stoves give you cancer or that biomass boilers will harm people. The message is that there must be a question mark against them and that we must move carefully with research based information before we embark on a biomass boiler programme because air quality is important and that we worsen air quality at our peril.

The European Commission thinks that air pollution reduces life expectancy on average by none months, and poor air quality in the UK is thought to cause 32,000 premature deaths each year. We traditionally blame vehicle particulates for this.

In the 1950s the Government introduced clean air legislation and “Smokeless Zones” which have had a profoundly beneficial effect on our health.In the UK there is no doubt that the Department of the Environment has been doing good work in improving air quality. My concern is that with an increased take up of biomass for energy this good work will be undone and that in twenty years from now we shall be facing similar public health problems that were caused by coal burning in the 1950s and 1960s.

Those in favour of biomass will point to improved filtering operations. I hope that they are right about the efficacy of the filters from biomass boilers. Even if they are right I think that we still have to factor in human behaviour. Boilers of all kinds need regular servicing and biomass boilers will not only need normal servicing but the filtration system will need to be regularly checked and renewed.

A biomass boiler will still work without proper servicing but will work in a very polluting way. Inertia is an important factor in human behaviour. How many people have their gas boilers serviced properly each year? How many condensing boilers no longer condense due to incorrect set up or lack of servicing? My fear is that inertia will lead to biomass boilers creating the very harm that we employ them to prevent.