The Environment Protection and Heritage Council's Standing Committee decided on 13 March 2008 to develop a nationally consistent approach to the management of woodheaters. This seems like good news, but sadly, policies on woodheaters have so far paid far more attention to the profits of the woodheater industry than our health. For example, every kg of PM10 emitted to Sydney's air is estimated to have health costs of about $132, so, based on average wood used and average emission rates from the real-life tests (Todd and Greenwood 2006), the health costs of the average new woodheater in Sydney will exceed $1600 per year (see below).
Although simple modifications could dramatically reduce emissions (e.g. door-activated timers to supply adequate air for 20 minutes after re-loading), even two years after publication of the real-life test results, there is no sign or the standard being changed so that new woodheaters can't produce really excessive emissions for hours on end under common real-life operation. This failure means that many heaters on sale today are likely to have health costs of thousands of dollars per year over their 15-20 year life-spans.

A new heater burning overnight emits more pollution than driving a car for a year (enough to pollute 0.6 kilometres x 0.6 km x 10 m to 50 ug/m3); smoky heaters also cause more global warming than heating the same house with gas

Todd (2008) conducted a survey of how woodheaters are operated. About one-fifth of the time (17.5%), people re-load the heater and immediately turn the air control to its lowest setting. This can dramatically increase pollution. Todd and Greenwood (2006) measured emissions from 4 new heaters (1 small, 3 large) using a proposed alternative test where the air control was turned to low after 2 minutes, instead of the AS4013 requirement of keeping the air on high until 20% of the fuel had been burned.

Leaving the control on high for 2 minutes is not as bad as immediately turning it to low, but it still produced lots of smoke. One heater emitted 183 grams of particulates and a second 175 grams over the next 8 hours. This is the same as about a year's worth of driving for a passenger car (18,000 km).

Under windless conditions 183 g of particles is enough to pollute an area 0.6 kilometres x 0.6 kilometres x 10 metres high to the NEPM PM10 standard of 50 ug/m3. It's also enough to pollute an area 1.2 km x 0.6 km x 10 metres to the NEPM PM2.5 standard of 25 ug/m3. Even worse, air below the NEPM standard is not considered safe – Dr Fay Johnston's recent study of bushfire smoke in Darwin found that an increase of just 10 ug/m3 in daily average PM10 (only 20% of the NEPM standard) increased hospital admissions for respiratory complaints by 8% with an even greater increase of 17% for indigenous Australians. This means that air that at the NEPM standard of 50 ug/m3 will be associated with increased respiratory complaints of 40% overall and 85% for indigenous Australians – not exactly what most people would consider 'safe'.

Large heaters produce lots of heat on high burn (the 3 large heaters averaged 12.4 kW), so most woodheaters spend a high proportion of time on low burn, with emissions according to the alternative test of 22.1 and 21.3 grams per hour (17.5 and 22.7 g/kg of wood, or 1793 and 1335 mg/MJ). These emissions are probably more representative of typical emissions than the average over all burn rates of all 4 heaters (6.3 g/kg.) With estimated average wood consumption of 1.9 tonnes per year in Sydney, the average new heater in Sydney is likely to emit 12-24 kg of particulates per year. Every kg of PM10 emitted to Sydney's air is estimated to have health costs of about $132, so the average new woodheater in Sydney is likely to have health costs of about $1600-$3,000 per year.

A Swedish study measured particle and methane emissions from new heaters and older smoky heaters. New heaters averaged 37 mg particles per MJ of heat. Older heaters emitted 103-350 mg/MJ with the worst heater producing 2200 mg/MJ when incorrectly operated – only marginally worse than the emissions on low burn of two of the brand-new Australian heaters in the alternative test. Incomplete burning produces large quantities of smoke and also methane (CH4), which causes 23 times as much global warming as the same amount of carbon dioxide (CO2). The heater that emitted 2200 mg particles/MJ also emitted 4.8 g CH4/MJ, equivalent to 110 g of CO2. This is higher than the 75 g CO2/MJ emitted by an oil-fired burner. The Swedish researchers commented: "Especially from an old-type boiler the methane emissions could be high and the effect on climate change then may become larger than that of an oil boiler." (See: Johansson et al., Atmospheric Environment 38 (2004) 4183–4195).

In Oct 2007, Prof Joel Schwartz, Depts of Environmental Health and Epidemiology, Harvard University, testified to the US House of Representatives Committee on Oversight and Government Reform. Prof Schwartz again pointed out that reducing pollution saves lives: "Most recently, we conducted a further ten-year follow-up on the participants (of the 'Six Cities' Study), after air pollution controls had led to reductions in particle concentrations. Figure 3, shows the results from this most recent analysis. In cities where particle concentrations fell substantially, mortality rates fell substantially, whereas in cities where there was little change in particle concentrations, the mortality rate changed little."

Prof Schwartz also noted that black carbon (BC) from diesel engines, coal and biomass burning may be more dangerous than other fine particles, but that "Progress has also been made recently on understanding how these particles affect heart disease. For example, we have reported that a measure of arterial stiffness is increased following BC (black carbon) exposure, that inflammatory proteins in the blood, which are risk factors for heart attacks, are increased following BC exposure, and that depression of the ST segment of the electrocardiogram, and indicator of either inflammation in the heart, or its failure to obtain enough oxygen, was increased following BC exposure.

Although the US EPA's recent standards for new diesel engines, and the EU upcoming standards, will result in emissions reductions of more than 90%, there is no requirement for retrofitting, despite diesel engine lifetimes that are typically 30 years. Hence there is scope for interventions. Retrofit kits are on the commercial market today. Indeed, London required all 6000 existing buses to be retrofit with particle filters in a two-year period, and their entire fleet is now low emitting vehicles.

McMaster University chemist Brian McCarry says the toxic content of smoke from fireplaces and old-fashioned wood stoves is similar to that of diesel exhaust and tobacco smoke.

"PM10 ranged from 6.4 – 70.0 μg/m3 (mean 19.1) … We observed increases of approximately 8% for all respiratory admissions, 20% for COPD and 13% for asthma admissions with incremental rises of 10 μg/m3 of PM10 …

Air pollution heavy in small particles may cause blood clots in the legs, the same condition air travellers call "economy class syndrome", according to a study published in May 08 in the Archives of Internal Medicine. Dr. Andrea Baccarelli of the Harvard School of Public Health in Boston and colleagues compared 870 people in Italy who had developed deep vein thrombosis between 1995 and 2005 with 1,210 others living in the same region who did not have the problem. They found that for every increase in particulate matter of 10 micrograms per square metre the previous year, the risk of deep vein thrombosis increased by 70 percent.

Just a few hours of exposure to particulate matter air pollution can increase blood pressure and harm blood vessel function within 24 hours, a new study finds. The findings may explain why air pollution can trigger a range of cardiovascular events such as heart attack, heart failure and stroke, the researchers said.

Particulate matter (PM) is a component of air pollution emitted from vehicles, power plants, and factories (with the NSW emissions inventory showing that woodheaters are the largest single source of PM10 and PM2.5 in Sydney). It's believed that PM is the 13th leading cause of death worldwide, but the link between PM and death hasn't been well understood.

Researcher Robert Brook, an assistant professor of medicine, division of cardiovascular medicine, University of Michigan explained details of a study of subjects in Toronto and Ann Arbor presented in May 2008 at the American Society of Hypertension annual meeting in New Orleans.

In Toronto, 30 adults, aged 18 to 50, were exposed for two hours to concentrated ambient PM (CAPS alone), CAPS and ozone, ozone alone, or filtered air. Exposure to air pollution that contains PM (CAP or CAP and ozone) resulted in an average diastolic blood pressure increase of 3.6 mm/Hg. Blood vessel function was impaired 24 hours after (but not immediately after) all exposures to all exposures containing PM, but not ozone alone.

In Ann Arbor, 50 adults were pre-treated with either the antioxidant vitamin C -- which blocks the vasoconstrictor hormone endothelin (bosentan) -- or placebo. Diastolic blood pressure increased between 2.5 and 4.0 mm/Hg during all exposures. However, blood pressure function was not impaired at any time after all exposures, and blood pressure returned to normal within 10 minutes after exposure.

The findings confirm that PM, not ozone, is responsible for the rapid increase in diastolic blood pressure and that this occurs only during actual inhalation of PM. The research also confirms that PM impairs blood vessel function one day after exposure. However, this blood vessel function response occurred only in Toronto, which suggests that the composition of PM or its source may play a role in determining that kind of response, the researchers said.

More news in a few months