The chemistry lab in your home is the kitchen.
Posted on May 1st, 2015

Dr Hector Perera        London

Cooking in hot or warm weather counties such as in Sri Lanka is much different to cooking in cold weather countries such as England and California. Sri Lanka fortunately has nearly all the year round warm weather unlike England and California. When our servants at back home cooked, I noticed the windows in the kitchen are always widely opened, never closed. This is an essential simple thing to bring in fresh air to the kitchen. The firewood needs oxygen to burn that means fresh air is needed. The servants just open the windows not with the idea of ventilation or to let the hot air or smoke out or to let fresh air for combustion of firewood. They open the windows because it is too warm inside the kitchens to cook with closed windows.  The kitchens are too warm due to radiated energy. The firewood stoves usually have a chimney just above the stoves or directly over the fires that allows the hot air to escape outside.

chemistry_cooking_apron_dark

Unlike in the past now Sri Lanka kitchens as well have modern gas and electric appliances for cooking. With gas cooking, I noticed that only in some places there are overhead extractor fans to exhaust the hot air. The purpose of the extractor fan is to get rid of smoke, burnt air and cooking fumes out of the kitchens otherwise those gases very likely to get into the other parts of the house. In the absence of these ventilating hoods, the persons involved in cooking and any young children at close proximity to the stove or the kitchen would have the highest exposure to these poisonous gases.

In colder climates such as in England and California, people may not want to use vents because they send warm indoor air outside. But the authors suggest that increasing the use of venting range hoods could reduce indoor air pollution as well as exposures to these chemicals. Even greater reductions could be achievable with improved hoods that capture pollutants more effectively, or quieter hoods that people are more likely to turn on.

A vent is a solution but not the only solution,” says Greg Diette, a Johns Hopkins University professor of medicine, epidemiology, and environmental health sciences. Another solution is to swap out the stove [for an electric model].” Diette has also tested a promising air cleaner that adsorbs gases.

Charles J. Wechsler, an adjunct professor with the Environmental and Occupational Health Sciences Institute, Rutgers University, points out that adsorbents have finite life spans, but it can be difficult to know when it’s time to change them. An exhaust system that incorporates a heat exchanger might be more promising,” he says. Such units are used in Scandinavia.” Heat exchangers reduce heat loss to the outdoors.

Air pollution in the kitchen

Attention has been paid to making buildings more energy efficient which often means making them tighter,” or less leaky, to reduce heating and cooling costs ventilation has become increasingly important.

Dangers of Poor Ventilation

California homes to experience indoor air pollution at hazardous levels. They estimated that 60 percent of homes in the state that cook at least once a week with a gas stove can reach pollutant levels that would be illegal if found outdoors. That equates to 12 million Californians routinely exposed to nitrogen dioxide levels that exceed federal outdoor standards, 10 million exposed to formaldehyde exceeding federal standards and 1.7 million exposed to carbon monoxide exceeding ambient air standards in a typical week in winter.

When you are cooking, the extractor fan must set to work. The vents must be connected to the outside to let the poisonous gases out. The hood must work for front and back burners. If there is no extractor available then open the window in the kitchen for ventilation just like the cooking style in warm weather countries.

These pollutants can come both from the cooking burners especially gas burners but to a lesser extent electric burners also as well as from cooking itself. The primary health effect of nitrogen dioxide, which is also found in the fumes of any type of combustion, is an increased likelihood of respiratory problems. Exposure to carbon monoxide is most serious for those who suffer from cardiovascular disease as it can enter the bloodstream and reduce oxygen delivery to the body’s organs and tissues.

The indoor pollutant that scientists believe may be most harmful to human health is particles, including fine particles, which are less than 2.5 micrometres in diameter, and ultrafine particles, which are smaller than 1 micrometre. They are produced by both gas and electric burners and by cooking. They are potentially very harmful because they can enter the lungs and, for the smaller particles, enter the bloodstream or other tissues.

Electric burners produce ultrafine particles essentially by volatilizing dust. It’s the same process with your toaster, resistance heater or radiator if you haven’t used it for a while. After you turn it on, you can smell it­—it smells terrible. You’re smelling the chemicals that have been volatilized. Once they’re in the air, they re-condense into these ultrafine particles.

Researchers now understand that the process of cooking food and even simply operating stoves particularly gas appliances can emit a cocktail of potentially hazardous chemicals and compounds. Within our homes, these pollutants are less diluted than they are outdoors, and in the absence of proper ventilation, they often are trapped inside.

When we cook in gas or with electric cookers, there are a numbers of gases emit from the reaction. In high temperature, nitrogen burns with oxygen to form oxides of nitrogen that react with more oxygen to form nitrogen dioxide which reacts with water vapour to form nitrous and nitric acid. That means even if we inhale these gases they can react with our breath. That is one of the reasons I pointed out one must not cook in high temperature or with gas on full blast.

You might have noticed in some British TV cooking programmes those chefs pay no attention to the cooker flame and cook or toss the food on a cooking pan. The food and oil in contact with very hot cooking pan gives out loads of fumes but they ignore and just cook and say something while cooking.  They do not know any science in cooking, they just add this and that to the pan and sometimes they catch fire because those cooking aroma chemicals are volatile. In my opinion that kind of cooking do not teach the children or the adults but some children get discouraged to cook. Your comments are welcomed [email protected]

One Response to “The chemistry lab in your home is the kitchen.”

  1. Raj Says:

    Hector, you are barking up the wrong tree. The so called ‘your method’ is something everyone knows. Your articles are getting so boring. Especially when they are among the more important political stuff. Why don’t you try something like ‘new scientist’ ‘ විදුසර’for your ‘scholarly articles repeated 100 times.

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