[Closed] Gas cookers & indoor pollution

I read something about how having ovens on (electric or gas I think) for long time at high temps ie for a roast or baking bread can cause really bad indoor air pollution. I believe it's recommended to open windows and have the extractor on full if you are using the oven.

I'm not sure about gas but it wouldn't be surprising would it, it is burning fossil fuels in your kitchen.

If you burn pure methane in enough oxygen, I can’t understand how you would get nitrogen byproducts, soot and carbon monoxide. If you’re burning really shitty gas in poor oxygen environments, or really rich, then I can see some of those forming.

CH4 + 3 O2 should just form CO2 and 2 H2O

It sounds plausible enough, but feels like bollocks

Total bollocks, gas hobs burn really cleanly and should only give off water vapour and CO2 - open a window when cooking or turn an extractor on.

Gas hobs are the least of your air quality concerns in a building - you will be getting constantly bombarded by dust, fungal spores, high concentrations of CO2 from breathing and poor ventilation, offgassing from modern man made materials, even formaldehyde leaking out of some materials after the manufacturing process.

I have some bad news: the cooking process releases pollutants. As well as heat, water vapour and, in the case of gas, products of combustion.

That’s why you have to provide extract ventilation to kitchens under the building regulations/technical standards.

I’ve designed a few commercial kitchens over the years and there is a factor you multiply the surface area of cooking surface to obtain the minimum air extraction rate. From memory it’s 0.35 for gas and 0.25 for electricity. I always put that down to products of combustion.

With all pollutants the best solution is remove them at source (i.e. cooker extract hood).

From memory, barbecue grills are the most polluting/worst. I recall being told that they are worse than smoking...

Next time I’ve my work laptop fired up I’ll take a look at the BESA and CIBSE guidance, see if it states anything specifically about pollutant make up.

I'm going to have to agree with Metalheart on this one.
I'm a commercial catering engineer by trade, and have to test the air quality in kitchens as part of their annual gas saftey testing.

The amount of regulations for ventilation in commercial kitchens is staggering.

In an ideal situation, with a brand new appliance, with the correct fluing, and make up air to achieve perfect combustion, then you shouldn't have any problems.

I have never found this situation in the 15+ years I have done this job, and have had to shut down a fair few kitchens because the staff felt a bit woozy when using the kit, and once the air quality was tested, the kitchen was basically a fancy stainless steel gas chamber.

The minute you start actually cooking on your fancy new hob or oven, contaminants start being released, being sucked into the ventilation system, or back into the burner venturi's causing the perfect stoichiometric ratio to fail.

I'm a gas engineer, and the first thing I did when I moved into my new house was bin the gas hob and fit an induction version.

Looks like a very badly written article with third hand info, if you follow the breadcrumbs and read the linked material you will find more info:

What cooking with gas is putting in your air
One reason the debate over cooking pollution is so murky and easily confused is that cooking of any kind produces some pollutants that are harmful if not properly handled. Applying heat to food produces particles — tiny particles (PM10, or particulate matter 10 micrometers in diameter), tinier particles (PM2.5, or 2.5 micrometers in diameter), and even tinier “ultrafine” particles (100 nanometers in diameter) — that can exacerbate respiratory problems.

https://www.vox.com/energy-and-environment/2020/5/7/21247602/gas-stove-cooking-indoor-air-pollution-health-risks

I'm also wary of wish washy statements like

In May, a literature review by the think tank RMI highlighted EPA research that found homes with gas stoves have anywhere between 50 and 400 percent higher concentrations of nitrogen dioxide than homes without

50 to 400% higher than what? Whats the danger limit?

Lets dive deeper.

Here is the actual report if you don't want to read 2nd, 3rd or 4th hand nonsense:

https://info.rmi.org/l/310101/download-26132-/28871gq

Some stand out points:

Gas stoves emit numerous pollutants including
nitrogen dioxide and carbon monoxide.
Cooking food, regardless of the type of stove
used, produces certain pollutants, such as
particulate matter. To separate emissions
generated by the fuel or the food, a key
differential is combustion (burning) of gas.
Nitrogen dioxide (NO2) and carbon monoxide (CO)
are primary pollutants produced from combustion.
Nitrogen dioxide levels are consistently higher
in homes that cook with gas rather than electric
stoves, and cook for longer periods of time. Poorly
maintained stoves are more likely to emit elevated
levels of carbon monoxide.12
A 2014 literature review linked high NO2 emissions
with older, ill-maintained gas stoves that are
poorly ventilated.13 Older stoves likely emit higher
concentrations of pollutants, and those with gas
pilot lights add approximately 10 parts per billion
(ppb) to indoor NO2 levels.14 However, a 2014 study
simulating air pollution, showed that gas stoves
used without exhaust hoods can produce levels
of NO2 above EPA outdoor air quality standards.15
Their results are consistent with emissions
measurements of stoves conducted in homes
between 2011 and 2012.16

An odorless, colorless gas. A 2011–2013 study found that gas
stoves can substantially increase the risk of elevated CO in
the home.

The highest polluters are old badly maintained and ventilated stoves and ovens (say it aint so!) and all cooking can produce particulate content. Meanwhile a gas stove can substantially increase the risk of elevated CO, that's like saying having books increases your risk of fire. It's technically true but there are other factors that influence the end result. Whilst I'm not dismissing their findings it's not peer reviewed and should be read with a healthy dose of scepticism (funded by several environmental groups with a vested interest).

From memory it’s 0.35 for gas and 0.25 for electricity. I always put that down to products of combustion.

Yes, the biggest combustion products needing removing being CO2 and water. Electric hobs don't produce these, gas does. For every unit of CH4 burnt 2.75 units of CO2 will be released.

I’m a commercial catering engineer by trade, and have to test the air quality in kitchens as part of their annual gas saftey testing.

I have never found this situation in the 15+ years I have done this job, and have had to shut down a fair few kitchens because the staff felt a bit woozy when using the kit, and once the air quality was tested, the kitchen was basically a fancy stainless steel gas chamber.

That would be testing for CO and CO2 presumably? There is also a vast difference between a commercial or industrial kitchen and one found in the home.

Indeed there is a vast, vast difference between commercial regs and domestic, and yes we test for CO and CO2, and I apologize if i did not get my point across very well.

Having read the attached "Article" it does come across as the rantings of a swivel eyed lunatic, in a similar vein as anti 5G or anti-vaxers.

My point was that all cooking appliances will create airborne contaminants, whether it be gas, electric, or fairy dust powered, Its just Gas has the added complication of Products of Combustion,

Is Gas the worst thing in the world, being pushed on us by a shady secret cabal trying to poison us in our own homes for some nefarious reason... NO don't be daft, that would be wood burning stoves obviously 😉

That's cool, sorry if I came across as arguing, was just genuine questions.

The article is very poor, it seems to be 4th hand info at best (original paper > blurb > vox > theverge) which is what got my back up and that seems to have carried over into my responses. I will take some time to look at the original paper as, biased or not, it will have a lot to consider.

Total bollocks, gas hobs burn really cleanly and should only give off water vapour and CO2 – open a window when cooking or turn an extractor on.

Gas hobs are the least of your air quality concerns in a building – you will be getting constantly bombarded by dust, fungal spores, high concentrations of CO2 from breathing and poor ventilation, offgassing from modern man made materials, even formaldehyde leaking out of some materials after the manufacturing process.

This.

From memory, barbecue grills are the most polluting/worst. I recall being told that they are worse than smoking…

Isn't bbq grilling outdoor only. I only use oven with cast iron casserole pot.

Technically nitrogen oxides can form as they need a temperature over 1600C and methane burns around 1920C. But thats where my point about 50-400% increases in concentrations comes in.

A 400% increase in background radiation (2 microsieverts) is terrifying to most but actually nothing at all. Even a 4000% increase, whilst being a significant source wouldn't hit your annual legal dose limit, to hit that you would need something like a 10000% dose rate increase and stand in the exact same spot for an entire year. Note that is whole body dose and legal limits are not the same as safe limits (they are kept lower for obvious reasons). Without putting these figures into context we have no way of understanding them.

I won't be trusting any of your analysis @squirrelking as you don't even know what gas we burn on our hobs.

We burn propane m8 🙂

We burn propane m8 🙂

Sounds like he knows more than you do. I shall choose to ignore you.

-uk mains supply is mostly CH4