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Pollution due to cooking, a rising concern for urban households

cooking indoor pollution

When we think of air pollution, an image of hazy smog over the city or black smoke spewing out of vehicles comes to mind. Often, we do not consider indoor air pollution that we may all be creating every day, in our houses, while cooking dinner in our kitchens. Or how sometimes it can be much worse than outdoor pollution, because the pollutants tend to build up and persist in indoor closed spaces.

The Death toll

India State-Level Disease Burden Initiative published a comprehensive estimate of deaths in india which states that out of 12.4 lakh deaths due to air pollution in 2017, 4.8 lakh deaths were attributed to household air pollution. The health risks are especially serious in rural areas where people are routinely being exposed to household air pollutants at levels that are lethal due to poor ventilation and use of cooking fuels like firewood and cow dung which emit substantial amounts of toxic pollutants.
According to a World Health Organisation report, smoke from such fuels inhaled by women is equivalent to smoking 400 cigarettes in an hour and causes severe respitory and other diseases.

In fact, each year globally, 3.8 million people die prematurely from illness attributable to household air pollution due to unclean cooking fuel (biomass and kerosene).

Out of there 3.8 million deaths,

  • 27% are due to pneumonia
  • 18% from stroke
  • 27% from ischaemic heart disease
  • 20% from chronic obstructive pulmonary disease (COPD)
  • 8% from lung cancer.

Government's efforts towards cleaner cooking fuels

Aware of the health risks of using biomass for cooking, the government has been trying to incentivise the use of cleaner fuels like LPG with the implementation of subsidy schemes such as Deepam scheme (Andhra Pradesh /Telangana), and more recent national level schemes such as Rajiv Gandhi LPG scheme and Pradhan Mantri Ujjwala Yojana. Since its launch in May 2016, under the “Ujjwala Scheme” 3.3 crore new LPG connections have been issued. It has been a successful programme with impressive growth in the number of LPG connections. Unfortunately consumption numbers haven't seen the same growth as beneficiaries in rural areas are resorting back to dirtier fuels and not refilling cylinders due to high cost of even the subsidised cylinder at ~ Rs. 450.

That said, since 2007, the contribution of household air pollution to ambient air pollution has fallen in the range of 40%-50%, as 80 percent households have switched from traditional, solid fuel-burning chulas to cleaner, more efficient cooking fuels such as LPG and electricity.

Now it may seem like this problem is confined to rural areas, however it is essential to note that indoor pollution due to cooking can be harmful in urban areas with cleaner LPG cooking fuel as well.

So what is making cooking in urban homes a source of indoor pollution?

Cooking is an act of controlled combustion and the gas stoves we use indoors inevitably emit harmful gases. While you are cooking a healthy meal in your kitchen, you might be exposing yourself and your family to unsafe levels of particulate matter, nitrogen dioxide, carbon monoxide, and chlorofluorocarbons.

indoor pollution due to cooking

Multiple factors effect the amount and toxicity of air pollutants released while cooking.

  1. Cooking Oil Used : Scientists have discovered that heating up vegetable oils leads to the release of high concentrations of chemicals called aldehydes, which have been linked to illnesses including cancer, heart disease and dementia. Sunflower oil and vegetable oil produced aldehydes at levels 20 times higher than recommended by the WHO and the emissions are even higher when these oils are reused for cooking (which is best to be avoided altogether). Olive oil is one of the better options followed by rapeseed oil, butter and goose fat which produces far fewer harmful chemicals.
  2. The method of cooking : Levels of emission increases with increase in temperature of oil. A study suggests that most contributing to emissions was deep frying, followed by pan frying then by stir frying. It suggests that using gentle cooking methods (e.g., stir frying) can reduce the production of aldehyde which are believed to be carcinogenic- related to some neurodegenerative diseases and some types of cancer.
  3. Cooking fuel used : Amongst the various options available for cooking fuel, firewood, biomass and pellet are the most polluting, kerosene is relatively cleaner, and natural gas and Liquefied Petroleum Gas (LPG) are the cleanest option with LPG emitting 50 times fewer pollutants than biomass burning.
  4. Stove sytem used : Gas stoves produce more NO2 than electric stoves but are significantly better than traditional chulhas in terms of PM emissions. Electric stoves are most beneficial in terms of indoor pollution as they were found to decrease kitchen NO2 concentration by 51% according to study, but are often infeasible due to their limitation of temperature control. An upgrade from regular gas stoves to those with automatic spark ignitions can help reduce LPG leakage and also remove the need to use match sticks which release chemical vapours (the likes of phosphorous, etc) in the air.

While the above points help you reduce the toxicity of the fumes generated during cooking, there is no substitute to good ventilation while cooking. Please make sure to turn on your exhaust fan and kitchen chimneys when cooking to ensure that fumes from cooking don't accumulate in the house and lead to health issues for your family. Air purifiers can also be effective at reducing NO2 concentrations due to cooking by 27%.

We hope this article will help you minimize indoor air pollution due to cooking. Please leave your thoughts and questions in the comments below.

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Airveda team is a group of people helping everyone breathe well and live well.