`The problem lies not just in stoves but in solid fuels themselves'
Kalpana Balakrishnan, director, WHO Collaborating Center for Occupational and Environmental Health, Sri Ramachandra University, Chennai, who was part of the study, talks about the research and the way ahead
What are the WHO-prescribed emission guidelines for cook stoves based on solid fuel? The guideline value for exposure to fine particulate matter (PM2.5) is 10 microgram/ m3 (annual mean). WHO also provides three interim targets (such as 35 followed by 25 and 15 microgram/m3 (annual mean) for PM2.5) to gradually reduce health risks from a high level of pollution and assess progress towards achieving the guideline values. Achieving even the interim standards appears farfetched for now.
What does your study reveal? Of the six commercially available stoves we tested, none came close to meeting the World Health Organization
( WHO) air quality guideline val- ues. In fact, none of them consistently achieved even the interim standards. We would like everyone, including manufacturers in the field, to realise that the focus in designing these stoves should not be limited to improving efficiency, but be extended to making them clean enough to attain the health benchmark for air quality over a period of long-term usage. The study has also highlighted the key role of household-level factors. For instance, a single pot stove is often not enough for a household's basic meal requirements. This forces people to use the old stoves in addition to newer ones and air quality inside the house does not improve. Quality of fuel is another critical matter. Sometimes the fuel may not be well-chopped, may be wet or just be of the wrong type - all leading to greater inefficiency in burning. Also, exposures in excess of guideline values may be experienced even in clean fuel households located in communities using solid fuels.
Which stove was found to be the best? The per cent reduction in mean concentration of PM 2.5 over a 24-hour period ranged from 8.5 to 62.5 per cent for different stoves. Philips-HD 4012 Forced Draft stove was the only one to show statistically significant reduction (at 62.5 per cent). The Oorja Forced Draft gasifier stove produced 20 per cent reductions but both were far from WHO air quality guidelines and reported to be cumbersome to use.
Are technical bottlenecks stalling us from building stoves that achieve WHO-prescribed emission levels? The problem lies not just in the stoves but also in solid fuels themselves, that burn very inefficiently. Our technological knowhow does not allow us to build a stove in the ` 2,000-`3,000 bracket that burns fuel efficiently enough to match WHO standards. In trying for greater efficiency, the costs often shoot up. Till a breakthrough in clean technology occurs, the need of the hour is to move to cleaner fuels like LPG and electricity.
How can the government better implement schemes like the National Biomass Cookstove Initiative (NBCI)? The NBCI was constituted to provide technologies that are comparable to LPG or other clean fuels. But we have found that cook stoves currently approved based on improvements in efficiency, cannot help attain WHO standards of air quality. Although India has been a pioneer in looking at more energy-efficient stoves, the aspect of health benefits of a cleaner fuel and stove have not been central in these discussions. There is now an increasing momentum to start evaluating stoves based on their health impact. This will change the course of things.