[Stoves] Quotes from 2015 WHO Indoor Air Quality Guidelines

Fri Oct 21 12:52:41 CDT 2016

Dear Dean at Aprovecho

This study raises some interesting questions. As Aprovecho has had vented Rocket Stoves for some years, it is a surprise that you did not report the performance of a vented Rocket stove as well as the unvented ones.

I mention this because the WHO model which underlies this study excludes improved chimney stoves from their modeling assumptions. They admit there are improved stoves, but not that there are improved chimney stoves. In your report you have looked at baseline (unimproved) chimney stoves. But an intervention would surely include an improved chimney stove which would probably (based on experience) reduce IAP to approximately zero.

This begs the question: why were not your cleanest stoves included in the report on solid fuel burning? If the point is to have clean kitchen air, surely it is obvious that the best available technologies would be promoted?

Someone reading this report may overlook that not realise that your have clean chimney stoves that were not included in the survey. It is bound to lead the casual reader to the erroneous conclusion that solid fuels cannot be burned cleanly enough to be used indoors, which you showed years ago is quite possible. You should promote your best products!

I have tested and reported numerous stoves that not only produce extremely low emissions but they are also fitted with chimneys which remove all emissions from the home. The possibility that these stoves exist is not mentioned in the report. The  modeled exposure (again presumed to be made using the Berkeley/WHO single box model – yes?) gives 50 micrograms per cubic metre based on an unimproved chimney stove. Those 3-star stoves in the CSI Indonesia Pilot with >80% reduction and are connected to a chimney reduce that value of 50 to less than 10, which is below the WHO’s new proposed limit for 24 hr exposure. Most of the stoves are well over an 80% reduction. I feel this is worth reporting, given that it meets the WHO’s long term objectives to promote clean modern cooking.

Regards
Crispin

From: Aprovecho Research Center [mailto:info=aprovecho.org at send.aweber.com] On Behalf Of Aprovecho Research Center
Sent: 17-Oct-16 09:16
To: crispinpigott at outlook.com
Subject: Quotes from 2015 WHO Indoor Air Quality Guidelines

<http://clicks.aweber.com/y/ct/?l=NCNbA&m=gI60srsvtpwbCjE&b=X6gmw1YioKMrV.1tbnZ7OQ>

Quotes from WHO 2014 Indoor Air Quality Guidelines
Unvented Rocket stove reduced PM2.5 by an average of 48% in field studies

Modelled 24-hour PM2.5 concentrations derived from field-based emissions rates of the rocket stove (which should be more comparable to observed levels of air pollution than laboratory-based rates), had a mode of around 500 μg/m3, a reduction of around 300 μg/m3, or nearly 40% compared to the traditional chulha. CO emissions were reduced from a mode of around 11 mg/m3 to 5 mg/m3, or by around 55%; this concentration of CO for the rocket stove (5 mg/m3) lies below the WHO 24-hour AQG.

The review of intervention impacts (see Review 6) found that this type of stove (Rocket) reduced PM2.5 by an average of 260 μg/m3 and CO by 3.41 ppm (3.9 mg/m3), with weighted mean percentage reductions of 48% and 39% respectively, and post intervention means of 410 μg/m3 and 6.6 ppm (7.6 mg/m3) respectively. Given the variability in data, devices, fuel used and other factors, these results can be considered consistent.

Chimneys: largest reductions in emission levels of all stoves and fuels

On average… it is expected that emissions entering the room from vented stoves are 75% lower than with unvented stoves. The review of intervention impacts (see Review 6) found that solid fuel stoves with chimneys (for which there were 23 and 22 estimates for PM2.5 and CO respectively) did indeed achieve a greater reduction of PM2.5 and CO than unvented stoves. This reduction was 63% for both pollutants, with post-intervention means of 370 μg/m3 and 4.2 ppm (4.8 mg/m3) for PM2.5 and CO respectively.

It should be noted, however, that several of the chimney-stove studies reported the largest reductions in emission levels of all stoves and fuels studied in the review (see Review 6). Three such studies reported PM2.5 levels of between 50 and 80 μg/m3 post-intervention, which are more consistent with the larger reductions predicted by the model.

These findings do not undermine the model but point towards reasons why this much better performance is not being achieved more widely. As discussed above, other sources in the home and AAP are likely to be responsible.

The WHO 2014 Indoor Air Quality Guidelines for Household Fuel Combustion may be downloaded here<http://clicks.aweber.com/y/ct/?l=NCNbA&m=gI60srsvtpwbCjE&b=S_FeUjpTzUnqYCV.YpWOtQ>.

The post Quotes from 2015 WHO Indoor Air Quality Guidelines<http://clicks.aweber.com/y/ct/?l=NCNbA&m=gI60srsvtpwbCjE&b=wcI4yKjCD4x2EkR.SqROiA> appeared first on Aprovecho<http://clicks.aweber.com/y/ct/?l=NCNbA&m=gI60srsvtpwbCjE&b=sV8RtgsvBlU_uxxXlb8vcw>.

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