Scrutable

article from a couple of years ago but just came up in a Twitter thread. it's about indoor pollution from cooking a roast dinner.

https://www.theguardian.com/environment ... than-delhi

I mean, it seems plausible but also, I dunno.

I think this is the paper. I've only skimmed it. I don't think it says how accurate their measuring devices are, but I would note that measuring fine particulates accurately, especially volatile ones, is difficult.

Assuming the measurements are sound, I think the Guardian report is pretty accurate. People have been concerned about indoor air quality for a while. It's rather difficult to manage. There is a huge diversity of potentially harmful substances in indoor air from a variety of sources, notably cooking, volatile organic compounds in furnishings, and burning solid fuels. This makes it difficult to do good epidemiology. Possibilities for regulation are limited: you could ban some VOCs (some people have suggested that flame retardants in furniture are of low value for their stated purpose and likely to cause unnecessary pollution, for instance), but justifying that will be difficult for many substances. And you can't regulate cooking.

One thing I would quibble with: “We know that inhaling particles, regardless of what they’re made of, is detrimental to health. Is it equally bad as inhaling exhaust from vehicle emissions? That we don’t know that yet.” I'm not sure the first part is true. PM is hugely heterogeneous in terms of size fraction and composition, and we really only know what the effects of the overall cocktail are. It's not obvious to me that food-derived fats and oils would be particularly harmful; they might cause lung damage, I suppose, but in the bloodstream they're just food. (OK, food that hasn't been decomposed by the intestines.)

Worse than Delhi? Sometimes my kitchen has a haze visible in across a distance of a couple of metres, so I should definitely say so. But that's a short-term peak.

According to the Guardian article...

Cooking a Sunday roast can drive indoor air pollution far above the levels found in the most polluted cities on Earth, scientists have said.

Researchers found that roasting meat and vegetables, and using a gas hob, released a surge of fine particles that could make household air dirtier than that in Delhi.

Probably down to people trying to make roast potatoes with "healthy oils" - use goose fat. Less smoke!

I'm reminded of David Mitchell's response on QI when told that kitchen chopping boards were more contaminated than toilet seats. Well, that's fine, because we aren't seeing huge amounts of food poisoning from contaminated chopping boards.

Similarly, humans have cooked food in similar ways for hundreds if not thousands of years, and these days are much cleaner than probably ever before. We can cope with short-term high particulates, especially when those particulates appear to be something (food-derived fats) which is quite easily broken down. Delhi's fine particulates are from things like soot which isn't as easily broken down by the body, and aren't short-term but continual.

Martin_B wrote: ↑

Sat Aug 20, 2022 10:08 pm

I'm reminded of David Mitchell's response on QI when told that kitchen chopping boards were more contaminated than toilet seats. Well, that's fine, because we aren't seeing huge amounts of food poisoning from contaminated chopping boards.

Similarly, humans have cooked food in similar ways for hundreds if not thousands of years, and these days are much cleaner than probably ever before. We can cope with short-term high particulates, especially when those particulates appear to be something (food-derived fats) which is quite easily broken down. Delhi's fine particulates are from things like soot which isn't as easily broken down by the body, and aren't short-term but continual.

I have seen it claimed that the Intermediate Technology clay ovens - as well as reducing the amount of wood needed for cooking, also reduces indoor pollution due to them being more efficient than traditional cooking.

Which would, as you say, be pretty long term compared to most people's use of roasting. Unless one works in a kitchen.

I'm reminded of the supposedly large contribution to LA's smog problem blamed on all those flame grilled Whoppers.

jimbob wrote: ↑

Sun Aug 21, 2022 7:40 am

Martin_B wrote: ↑

Sat Aug 20, 2022 10:08 pm

I'm reminded of David Mitchell's response on QI when told that kitchen chopping boards were more contaminated than toilet seats. Well, that's fine, because we aren't seeing huge amounts of food poisoning from contaminated chopping boards.

Similarly, humans have cooked food in similar ways for hundreds if not thousands of years, and these days are much cleaner than probably ever before. We can cope with short-term high particulates, especially when those particulates appear to be something (food-derived fats) which is quite easily broken down. Delhi's fine particulates are from things like soot which isn't as easily broken down by the body, and aren't short-term but continual.

I have seen it claimed that the Intermediate Technology clay ovens - as well as reducing the amount of wood needed for cooking, also reduces indoor pollution due to them being more efficient than traditional cooking.

Which would, as you say, be pretty long term compared to most people's use of roasting. Unless one works in a kitchen.

Traditional cooking and clay ovens aren't usually used in houses that are tightly air-sealed to meet the energy efficiency requirements for modern western buildings, which are needed to reduce the use of fossil fuels. The air change rate in modern buildings is much lower than for traditional buildings, which means that particulate and CO2 levels can build up much more.

Martin Y wrote: ↑

Sun Aug 21, 2022 1:22 pm

I'm reminded of the supposedly large contribution to LA's smog problem blamed on all those flame grilled Whoppers.

God knows what you're getting when you walk past a Subway (in UK)

Martin Y wrote: ↑

Sun Aug 21, 2022 1:22 pm

I'm reminded of the supposedly large contribution to LA's smog problem blamed on all those flame grilled Whoppers.

That was probably an effort by the car industry to apply political pressure against California's much tighter emission requirements that means that cars have to be specifically built for that market.

dyqik wrote: ↑

Sun Aug 21, 2022 2:36 pm

Martin Y wrote: ↑

Sun Aug 21, 2022 1:22 pm

I'm reminded of the supposedly large contribution to LA's smog problem blamed on all those flame grilled Whoppers.

That was probably an effort by the car industry to apply political pressure against California's much tighter emission requirements that means that cars have to be specifically built for that market.

I recall someone saying that bicycles were the worst polluters on the road because of the dust from all the brake block wear.

Gfamily wrote: ↑

Sun Aug 21, 2022 4:32 pm

dyqik wrote: ↑

Sun Aug 21, 2022 2:36 pm

Martin Y wrote: ↑

Sun Aug 21, 2022 1:22 pm

I'm reminded of the supposedly large contribution to LA's smog problem blamed on all those flame grilled Whoppers.

That was probably an effort by the car industry to apply political pressure against California's much tighter emission requirements that means that cars have to be specifically built for that market.

I recall someone saying that bicycles were the worst polluters on the road because of the dust from all the brake block wear.

What really? Not a joke? I've had "Cyclists produce CO2 even when they're not cycling.", but it was said in jest.

Compare the surface area of a bicycle brake block to that of a car tyre. A similar depth gets ground off each in its lifetime. Couple of orders of magnitude off, I reckon.

Martin Y wrote: ↑

Sun Aug 21, 2022 6:51 pm

Compare the surface area of a bicycle brake block to that of a car tyre. A similar depth gets ground off each in its lifetime. Couple of orders of magnitude off, I reckon.

I think it was something like "cars do tens of thousands of km, whereas bikes only do tens of hundreds".

Yes, total bobbins, but it was argued thus.

Martin Y wrote: ↑

Sun Aug 21, 2022 6:51 pm

Compare the surface area of a bicycle brake block to that of a car tyre. A similar depth gets ground off each in its lifetime. Couple of orders of magnitude off, I reckon.

the braking forces are far smaller too. Also, I thought a lot of the particulates were due to the tyres. And again it would be a function of the forces involved.

Sciolus wrote: ↑

Sat Aug 20, 2022 6:49 pm

It's not obvious to me that food-derived fats and oils would be particularly harmful; they might cause lung damage, I suppose, but in the bloodstream they're just food. (OK, food that hasn't been decomposed by the intestines.)

I remember them looking into lung cancer and working in kitchens. There's a paper here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7508228/

We used data from the SYNERGY project including pooled information on lifetime work histories and smoking habits from 16 case–control studies conducted in Europe, Canada, New Zealand, and China.

Before adjustment for smoking, we observed an increased risk of lung cancer in male cooks, but not in female cooks. After adjusting, there was no increased risk and no significant exposure–response relationship. Nevertheless, subgroup analyses highlighted some possible excess risks of squamous cell carcinoma and small cell carcinoma in female cooks.

The subgroup analyses showing some excess risks among female cooks require cautious interpretation.

jdc wrote: ↑

Mon Aug 22, 2022 10:45 pm

Sciolus wrote: ↑

Sat Aug 20, 2022 6:49 pm

It's not obvious to me that food-derived fats and oils would be particularly harmful; they might cause lung damage, I suppose, but in the bloodstream they're just food. (OK, food that hasn't been decomposed by the intestines.)

I remember them looking into lung cancer and working in kitchens. There's a paper here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7508228/

We used data from the SYNERGY project including pooled information on lifetime work histories and smoking habits from 16 case–control studies conducted in Europe, Canada, New Zealand, and China.

Before adjustment for smoking, we observed an increased risk of lung cancer in male cooks, but not in female cooks. After adjusting, there was no increased risk and no significant exposure–response relationship. Nevertheless, subgroup analyses highlighted some possible excess risks of squamous cell carcinoma and small cell carcinoma in female cooks.

The subgroup analyses showing some excess risks among female cooks require cautious interpretation.

That suggests to me that prolonged exposure, day-after-day poses some increased risk to male cooks and may pose some increased risk to female cooks (it would be interesting to know why they are different!). But they are working in these high particulate workplaces for many hours a day.

If you are cooking a roast dinner once or twice a week that's a much lower exposure time, which greater recovery periods between exposures, so the average household would have a risk profile. (It might be a bit higher for the main household cook, but even then ~1-2 hours a day rather than ~8 hours a day.)

Martin_B wrote: ↑

Tue Aug 23, 2022 1:00 am

jdc wrote: ↑

Mon Aug 22, 2022 10:45 pm

Sciolus wrote: ↑

Sat Aug 20, 2022 6:49 pm

It's not obvious to me that food-derived fats and oils would be particularly harmful; they might cause lung damage, I suppose, but in the bloodstream they're just food. (OK, food that hasn't been decomposed by the intestines.)

I remember them looking into lung cancer and working in kitchens. There's a paper here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7508228/

We used data from the SYNERGY project including pooled information on lifetime work histories and smoking habits from 16 case–control studies conducted in Europe, Canada, New Zealand, and China.

Before adjustment for smoking, we observed an increased risk of lung cancer in male cooks, but not in female cooks. After adjusting, there was no increased risk and no significant exposure–response relationship. Nevertheless, subgroup analyses highlighted some possible excess risks of squamous cell carcinoma and small cell carcinoma in female cooks.

The subgroup analyses showing some excess risks among female cooks require cautious interpretation.

That suggests to me that prolonged exposure, day-after-day poses some increased risk to male cooks and may pose some increased risk to female cooks (it would be interesting to know why they are different!). But they are working in these high particulate workplaces for many hours a day.

If you are cooking a roast dinner once or twice a week that's a much lower exposure time, which greater recovery periods between exposures, so the average household would have a risk profile. (It might be a bit higher for the main household cook, but even then ~1-2 hours a day rather than ~8 hours a day.)

That's not how I interpreted it - the bit I've just highlighted says they found no increased risk after adjusting for smoking.

I'm just taking a look now and from the full paper's results section: "After adjusting for smoking, there was no statistically significantly increased risk of lung cancer in cooks overall, neither for men nor for women. The OR2 for lung cancer among male cooks was 0.98 (95% CI, 0.83 to 1.17) and among female cooks 1.06 (95% CI, 0.85 to 1.31)."

And further down: "Analyses restricted to current smokers showed a borderline significantly increased risk among female cooks (OR2 = 1.49; 95% CI, 1.03 to 2.17) but no increased risk among male cooks (OR2 = 0.93; 95% CI, 0.74 to 1.17) [...] Analyses restricted to never smokers showed no increased risk among cooks of either sex, although the numbers of male nonsmoking cooks were so small that the OR was not very informative"

jdc wrote: ↑

Tue Aug 23, 2022 1:35 am

Martin_B wrote: ↑

Tue Aug 23, 2022 1:00 am

jdc wrote: ↑

Mon Aug 22, 2022 10:45 pm

I remember them looking into lung cancer and working in kitchens. There's a paper here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7508228/

That suggests to me that prolonged exposure, day-after-day poses some increased risk to male cooks and may pose some increased risk to female cooks (it would be interesting to know why they are different!). But they are working in these high particulate workplaces for many hours a day.

If you are cooking a roast dinner once or twice a week that's a much lower exposure time, which greater recovery periods between exposures, so the average household would have a risk profile. (It might be a bit higher for the main household cook, but even then ~1-2 hours a day rather than ~8 hours a day.)

That's not how I interpreted it - the bit I've just highlighted says they found no increased risk after adjusting for smoking.

I'm just taking a look now and from the full paper's results section: "After adjusting for smoking, there was no statistically significantly increased risk of lung cancer in cooks overall, neither for men nor for women. The OR2 for lung cancer among male cooks was 0.98 (95% CI, 0.83 to 1.17) and among female cooks 1.06 (95% CI, 0.85 to 1.31)."

And further down: "Analyses restricted to current smokers showed a borderline significantly increased risk among female cooks (OR2 = 1.49; 95% CI, 1.03 to 2.17) but no increased risk among male cooks (OR2 = 0.93; 95% CI, 0.74 to 1.17) [...] Analyses restricted to never smokers showed no increased risk among cooks of either sex, although the numbers of male nonsmoking cooks were so small that the OR was not very informative"

In that case, it's fairly definitive that cooking an occasional roast dinner doesn't cause dangerous indoor pollution.

thought this would be a thread of Brussels sprouts fart jokes

jdc wrote: ↑

Tue Aug 23, 2022 1:35 am

"the numbers of male nonsmoking cooks were so small that the OR was not very informative"

That's quite a striking conclusion itself.

Sciolus wrote: ↑

Tue Aug 23, 2022 7:35 am

jdc wrote: ↑

Tue Aug 23, 2022 1:35 am

"the numbers of male nonsmoking cooks were so small that the OR was not very informative"

That's quite a striking conclusion itself.

Fag break culture might be a welcome relief when you're working in a hot kitchen.

Martin_B wrote: ↑

Tue Aug 23, 2022 2:26 am

jdc wrote: ↑

Tue Aug 23, 2022 1:35 am

Martin_B wrote: ↑

Tue Aug 23, 2022 1:00 am

That suggests to me that prolonged exposure, day-after-day poses some increased risk to male cooks and may pose some increased risk to female cooks (it would be interesting to know why they are different!). But they are working in these high particulate workplaces for many hours a day.

If you are cooking a roast dinner once or twice a week that's a much lower exposure time, which greater recovery periods between exposures, so the average household would have a risk profile. (It might be a bit higher for the main household cook, but even then ~1-2 hours a day rather than ~8 hours a day.)

That's not how I interpreted it - the bit I've just highlighted says they found no increased risk after adjusting for smoking.

I'm just taking a look now and from the full paper's results section: "After adjusting for smoking, there was no statistically significantly increased risk of lung cancer in cooks overall, neither for men nor for women. The OR2 for lung cancer among male cooks was 0.98 (95% CI, 0.83 to 1.17) and among female cooks 1.06 (95% CI, 0.85 to 1.31)."

And further down: "Analyses restricted to current smokers showed a borderline significantly increased risk among female cooks (OR2 = 1.49; 95% CI, 1.03 to 2.17) but no increased risk among male cooks (OR2 = 0.93; 95% CI, 0.74 to 1.17) [...] Analyses restricted to never smokers showed no increased risk among cooks of either sex, although the numbers of male nonsmoking cooks were so small that the OR was not very informative"

In that case, it's fairly definitive that cooking an occasional roast dinner doesn't cause dangerous indoor pollution.

No, it's not that definitive.

Why can't people here understand that the ventilation in modern western houses is not the same as in professional kitchens or in houses in third world countries where cooking fires are used?

And as was just highlighted, this study does not seem to be nearly as powerful for non-smokers, or those not exposed to secondhand smoke.

While I doubt that the occasional roast dinner is dangerous, it's a completely different baseline risk and context to this study. Ventilation is everything to risks like this, as it is for CoVID infection risk, which is why CO2 monitors are so useful in CoVID infection prevention.

dyqik wrote: ↑

Tue Aug 23, 2022 10:55 am

No, it's not that definitive.

Why can't people here understand that the ventilation in modern western houses is not the same as in professional kitchens or in houses in third world countries where cooking fires are used?

I agree. Modern houses are sealed and have no natural ventilation.

Maybe this is just an example of the poor state of British housing and the brits on the forum can't grasp living somewhere that isn't draughty.

Woodchopper wrote: ↑

Tue Aug 23, 2022 12:22 pm

dyqik wrote: ↑

Tue Aug 23, 2022 10:55 am

No, it's not that definitive.

Why can't people here understand that the ventilation in modern western houses is not the same as in professional kitchens or in houses in third world countries where cooking fires are used?

I agree. Modern houses are sealed and have no natural ventilation.

Maybe this is just an example of the poor state of British housing and the brits on the forum can't grasp living somewhere that isn't draughty.

However, if you are talking about air pollution being from food oils, simple Brownian motion will lead to the oils coming into contact with walls, ceilings, worktops, clothing, you, etc, which will lead to a decrease in airborne pollution levels. As oil has a high adhesive qualities, this happens relatively quickly (compared to air pollution from soot particles). So even with relatively sealed houses with few draughts the air pollution from cooking a roast dinner will quickly reduce from the peak levels.

That's not to mention the use of extraction fans (or simply opening a window) if the air in the kitchen gets a bit stuffy.

Martin_B wrote: ↑

Wed Aug 24, 2022 1:41 am

Woodchopper wrote: ↑

Tue Aug 23, 2022 12:22 pm

dyqik wrote: ↑

Tue Aug 23, 2022 10:55 am

No, it's not that definitive.

Why can't people here understand that the ventilation in modern western houses is not the same as in professional kitchens or in houses in third world countries where cooking fires are used?

I agree. Modern houses are sealed and have no natural ventilation.

Maybe this is just an example of the poor state of British housing and the brits on the forum can't grasp living somewhere that isn't draughty.

However, if you are talking about air pollution being from food oils, simple Brownian motion will lead to the oils coming into contact with walls, ceilings, worktops, clothing, you, etc, which will lead to a decrease in airborne pollution levels. As oil has a high adhesive qualities, this happens relatively quickly (compared to air pollution from soot particles). So even with relatively sealed houses with few draughts the air pollution from cooking a roast dinner will quickly reduce from the peak levels.

That's not to mention the use of extraction fans (or simply opening a window) if the air in the kitchen gets a bit stuffy.

Small oil droplets and PM2.5 can't move against airflow. Extraction fans running is one of the main reasons that professional kitchens are not like home kitchens. And the point of this article is that you can't tell if the air is getting a bit stuffy until levels are really high.