Motion made, and Question proposed, That this House do now adjourn. —[Mr. Khan.]

I am pleased to have secured this debate this evening on open windrow composting. Let me say at the outset that I support the recycling of green waste. However, it must be done in a safe manner and without endangering the safety of those who live in close proximity to recycling sites. It is in that context that I want to make two points in my contribution—about the danger associated with this type of process, and about public safety.

I also want to take this opportunity to thank the Minister for her reply to me of 16 June 2008, which goes some way to answering some of my concerns, but I want to encourage her to go a little further. I will refer to her letter later and suggest how we may take the matter forward.

The problems associated with open windrow composting were brought to my attention by local residents in my constituency who were protesting against the proposal for a composting site near to the village of Hood Green in the hinterland to the Pennines. I know that matters to do with the site are for the local planning authority and not for this debate, but I want to speak about the dangers generally associated with the open windrow composting process and what can be done to mitigate them.

The process takes place on a large concrete base and the method of decay is helped by the natural internal combustion of the waste. As the green waste heats, the process of decay is facilitated. The waste is turned over by machine at intervals to ensure thorough decomposition. That agitation produces bioaerosols, which can be called organic dust. One such bioaerosol is Aspergillus fumigatus, a fungus that can cause serious respiratory damage and has been known to be fatal. There are other downsides to the process, including the odour that results—particularly from the run-off of rain, which can collect and stagnate. That adds to the sickening smell, which also attracts vermin and flies; they are a further hazard of the process.

I want to draw the Minister's attention to the Giessen study, which took place in Germany; I shall read from its introduction and conclusions in a moment. I want to do that because the Environment Agency advises a 250 m precautionary buffer zone, although from its website it appears that the agency is not too sure of what the distance should be. That is an important issue.

I contend that, on the evidence available, a 250 m buffer site is inadequate in many circumstances. In that context, I refer the Minister to a study carried out by scientists at the university of Giessen Institute for Hygiene and Environmental Medicine on the effects of bioaerosol-polluted outdoor air on the airways of residents. It is dated 14 November 2005. I am advised that, for some strange reason, the study was not included in the Health and Safety Executive review of research report 130.

The introduction to the study states:

"A team of doctors, process engineers, microbiologists and meteorologists were assembled, and conducted this investigation into the effects of bio aerosol polluted air on the airways of residents. The study was double blinded to the ongoing microbial levels. A total of 356 medical questionnaires were collected from residents near a green waste compost site and also from an unexposed residential control area. The prevalence of health complaints were assessed against distance from site and the recorded microbiological pollution levels...The site near Giessen, Germany processes yard trimmings, grass cuttings and organic waste. The material is shredded, formed in windrows and turned regularly. Throughput is approximately 12500m⁽³⁾ per year."

The conclusions of the study are of great interest, and I want to draw the Minister's attention to them:

"There is clear evidence of elevated health changes with residents living up to 500 metres from this green waste site. Mucus membrane infections are particularly elevated, shortness of breath is shown to be an effect of spore inhalation and excessive tiredness is distinctly linked to site emissions."

The study continues:

"This study is believed to be the first to actively show the causal link between levels of bio aerosols and health conditions. Other studies over the last 20 years have hypothesized over the effects on those living in close proximity to compost sites and have identified raised levels of fungal spores at 500 metres distant, but apart from stating that 'there is potential for chronic ill health, which may not yet have had time to manifest itself', no change in Environmental Agency recommendations for distances from sensitive receptors has yet emerged."

The agency referred to is of course the German environment agency. It concludes in its final paragraph:

"Fungal spores are common in air and every cubic metre of air breathed will contain a few minute spores. Generally the immune system can cope with levels above background, but in the area of a composting site the concentration of airborne spores is increased dramatically. Exposure should be limited wherever possible up to the 500 metre line where background levels then descend to normal."

In effect, the study is saying that we should have a buffer zone of 500 m. Given that it is the most comprehensive study that has been done, I am rather surprised that it was not included in the HSE review of research report 130.

The Minister will be aware of the Stourbridge case, where, on 10 December, a composting site that was within 250 m of residential homes was closed. A man who acted as a consultant to the group that opposed the site advises me that it was closed because of excessive amounts of odour and bioaerosol emissions; I know that the Environment Agency takes a different view. He has provided me with the medical backgrounds of 12 of the 14 victims. Two of the 12 were suffering from the Aspergillus fungus; the others had picked up different infections on top of their chest conditions. Since the closure, I am advised that the five people who have been followed up have all reported that their health has improved and that they are using only half the medicines that they were prescribed at the time when the site was open. If we not only look at the Giessen study but draw on the experience gained from Stourbridge, it is clear that important evidence links the victims to the inhalation of organic dust from those composting sites.

The Minister may be interested in the work that is being done at Sheffield university. The Environment Agency decided on its 250 m buffer zone on the basis of a study carried out on flat lands in Norfolk, but when people from Sheffield university investigated how the wind carries spores in the hinterland to the Pennines, they found that it blows up the hill and then forms a kind of vortex on the other side, carrying some of the spores up to 1 km further than was previously supposed. It is important that we take into consideration the terrain for which many composting applications are made. I understand from a similar study that the Californian authorities have decided to go with a 500 m buffer zone instead of the shorter one that was previously used.

As the Minister will be aware, there are alternatives to open windrow processing, including complete enclosure and a system called IVC—in-vessel composting—which operates almost like a low-pressure cooker and deals with the green waste without producing the bioaerosols.

Problems may be created in the work environment for employees, and that issue should also be considered closely.

The Minister wrote me a helpful letter—it included one point on which we may be able to make further progress—in which she referred to the development of amenity risk assessments at waste management facilities. She wrote:

"This project will help to develop methods for estimating downwind concentrations of bio-aerosols and focus on improving data availability to support research into dispersion modelling."

As I say, dispersion modelling is being done at Sheffield university. She went on to say:

"The report will describe a number of peer reviewed journal papers examining bio-aerosol production and dispersal."

It is in that context that I urge her to ask that the Environment Agency and the Health and Safety Executive, which has a public health function, look at the Giessen study. As far as I can see, it is the foremost study on composting in the community.

In conclusion, I ask the Minister to do four things. First, I would like her not only to ensure that the HSE and the Environment Agency review the Giessen study, but to encourage them to take a cautious view on recommendations of a more appropriate buffer zone, particularly in areas such as the hinterland to the Pennines, where it is very hilly and we get the sort of wind problems and vortexes to which I referred. I would also be pleased if she advises that research done before 2000 is outdated, because much of the relevant literature is more recent. The Cornell Waste Management Institute, which is an Ivy league institute, is making that recommendation. Will she ask the HSE to advise on the best and safest composting method for employees and the public? Finally, will she ask local authorities to defer any proposals for new sites until the Environment Agency and the HSE advice is available so that we can ensure public safety in the future?

I am very grateful to my hon. Friend Mr. Clapham for securing this debate, and for the excellent way in which he presented his case. I will attempt to answer his many questions and deal with the promises that he seeks from me.

As has been identified, open windrow composting is one of the forms of biological treatment of biodegradable waste that has increased in recent years in the move increasingly to recycle or recover waste and to reduce our reliance on landfill. Of course, however, composting is by no means new and it is, indeed, a process that occurs naturally, as my hon. Friend will appreciate. Good quality compost has a number of benefits, including its water-holding capability and as a sustainable alternative to peat, so it is important to us. It returns organic matter to the soil, sequestering carbon, and it can be used as a soil improver—in agricultural or landscape applications, for example—and as a growing medium for the horticultural industry.

At the heart of our waste strategy is the need to meet our European Union landfill directive targets. The amount of biodegradable municipal waste we send to landfill needs to fall to 11.2 million tonnes by 2010, 7.46 million tonnes by 2013 and 5.22 million tonnes by 2020. That is quite a challenge. We have already made progress, with the amount falling from 13.9 million tonnes in 2004-05 to 11.55 million tonnes in 2006-07. That achievement reflects the increase in waste being recycled and composted—from 27 per cent. in 2005-06 to more than 30 per cent. in 2006-07. A third of that figure is made up of composting.

Open windrow composting is the form of composting green waste that is carried out in our back gardens, our community composting schemes, in large public gardens and hotels, on farms and at other establishments. Composting is also carried out on a much larger commercial scale by operators contracted to handle source-segregated green waste collected by local authorities or delivered by the public to civic amenity sites.

Open windrow composting is less suited to dealing with other types of waste such as food waste or other contaminated biodegradable waste. As my hon. Friend said, other methods are more appropriate, for example, in-vessel composting, which must fulfil animal by-product regulations, and anaerobic digestion. The Government are encouraging that and we have announced a £10 million technology demonstrator programme for anaerobic digestion.

At the core of my hon. Friend's concerns are the risks that such activities pose to the environment and human health. As he said, a bioaerosol is a suspension of fine biological material in a gas. Bioaerosol particles are made up of a range of different types of particles, including fungal spores such as Aspergillus fumigatum and Penicillium. Of course, they occur naturally in urban and rural environments, and can aid the composting process.

It is important to stress that background figures vary from location to location, and with the seasons, ranging from less than 100 to more than several thousand particles per cubic metre. My hon. Friend is correct to say that the dispersal of bioaerosols will vary with atmospheric conditions. That is why the Health and Safety Executive reviewed a range of data from different sites, conditions and modelling techniques. My hon. Friend asked why the Giessen study was not included in the review. The reason is that the review was carried out before the publication of the Giessen study, so its inclusion was not possible.

The review, which was published in 2003, found that fungal particles generated at any site would drop to background levels within about 150 m. That is why the Health and Safety Executive has proposed a precautionary approach and recommended not 150 m but 250 m. By taking a bigger margin than is perhaps considered necessary, the HSE is confident that it has taken account of unexpected or extreme conditions.

My hon. Friend asked about specific wind speeds and dispersal. That works in a way that perhaps is contrary to his expectations. When the tiny particles are in the wind, if they are blown at speed in a specific location, they are more likely to clump together, form heavier particles and therefore fall to the ground more quickly. Of course, we would expect particles to travel as far as 1,000 m. They are being constantly spread throughout the atmosphere.

I accept that a gentle wind in a level area may take the spores further than a stronger breeze. However, in the Pennines, the modelling showed that the wind goes to the top of the hills and forms a vortex over them, carrying the spores much further and putting communities that are further away than 250 m in danger. I therefore believe that we should have a wider buffer zone.

My advice is that that dispersal mechanism reduces the density. Between us, we are unable to decide, so we probably need to leave the matter to the experts, but that is the advice that I have received.

The Environment Agency recently reviewed the 250 m limit, in the light of our recent increases in composting capacity, and concluded that it remained valid. Therefore, I am afraid that the Government cannot accept my hon. Friend's suggestion that all composting schemes throughout the country should be deferred until further research has been conducted. There are further research projects under way, which I shall mention, but he knows that I have given him chapter and verse on those, including their publication date and what they aim to achieve, in the letters that I have sent him.

All forms of waste recovery or disposal, including composting, are regulated to prevent harm to human health and the environment. That regulation is achieved in two ways: first, through the planning system and the requirement for planning permission for use or development of land; and, secondly, through an environmental permit, or in some cases a registered exemption from the Environment Agency. The aim is for the two systems to complement each another to achieve the overall control and protection required.

The Environment Agency is consulted, as part of the planning process, on environmental and human health considerations and, where composting sites are involved, takes the location of the site into account when permitting a site or registering an exemption. The Environment Agency requires permit applicants and those wishing to register exemptions to provide it with a site-specific bioaerosol risk assessment where the proposed composting facility will be within 250 m of dwellings or workplaces. That assessment will need to demonstrate that the levels of bioaerosols have dropped to background levels before reaching the first receptor, which means dwelling or workplace. Where prospective compost sites are more than 250 m from occupied premises, a more basic risk assessment is completed that does not require monitoring of bioaerosols, for the reasons that I have already given.

My hon. Friend referred in his correspondence to the site at Hood Green, which is just over 300 m from the nearest house. The nearest workplace is 210 m away, but is an unstaffed sewage treatment works. The prospective operator was required to submit only a basic risk assessment, as part of a registration process for the waste exemption. That assessment determined that the risk was acceptable, given the distance of the site from the nearest dwelling. That meets the Environment Agency's requirements for assessing exemption registrations when sites are more than 250 m from a dwelling or workplace.

It is a fundamental principle of the planning system that each application must be decided on its individual planning merits, following consultation with those potentially affected by a development. As my hon. Friend has acknowledged, given that there is an outstanding application for planning permission in respect of the Hood Green site, it would be inappropriate for me to comment further at this stage. However, I understand that the occupier of the site has already registered an exemption with the Environment Agency in respect of the proposed composting operation. The Environment Agency has advised me that it has considered the request in detail and has checked the proposed composting activity could meet the terms of the exemption before placing it on the public register of exempt activities.

Under the terms of the current exemption provided for in legislation, the amount of waste being composted at any time must not exceed 1,000 cu m. The Environment Agency has advised me that it will inspect the site if it becomes operational. If the Environment Agency finds that the site is causing harm to the environment or resulting in noise or odour nuisance, it can remove the exemption from the register. The Environment Agency can also take enforcement action, but only if there are any grounds to do so once the activity has commenced. If the composting activity is unable to meet the requirements of the exemption and is removed from the public register, the operator will be required to apply for an environmental permit to carry out the activity. The site will be subject to inspection by the Environment Agency to ensure that the operations are being carried out to an appropriate standard and in compliance with the rules of the exemption.

My hon. Friend referred to the composting site in Stourbridge. In that case, the Environment Agency refused to register an exemption because of its concerns about nuisance and other local impacts. I have checked the details specifically in relation to bioaerosols, and the Environment Agency has said that they were not the reason for closing the site. The reasons were dust, noise and smells, all of which have an impact on local people, and it was as a consequence of those factors that the agency exercised its enforcement powers. I understand that bioaerosol monitoring has taken place at the site, and they were not one of the factors involved. It is really important to assure people of that.

My hon. Friend referred to the follow-up research that he says has been carried out. I have not seen it, but if there is value in the work, we will undoubtedly need to look at it. The Environment Agency and others who are carrying out research and producing reports will clearly need to look at it as well. My hon. Friend has described a very small sample, however. As a scientist myself, I think that it might be difficult to draw conclusions from a sample of that size.

I share many of the concerns that my hon. Friend Mr. Clapham has expressed, in relation to my own constituency. I hope that the Minister will refer to the research that he has mentioned, as I believe that it could have an impact on the decisions that she might ultimately make.

May I give my hon. Friend, and my hon. Friend the Member for Barnsley, West and Penistone, that assurance? I am determined to look into all the issues that have been raised. As I said in my letters, if the research throws up new factors, it will of course be appropriate to review the situation, and we will have to look at the conditions surrounding the permits and exemptions—

The motion having been made after Ten o'clock, and the debate having continued for half an hour, Mr. Speaker adjourned the House without Question put, pursuant to the Standing Order.

Adjourned at thirteen minutes to Eleven o'clock.