ultrafine particles and nitrogen oxides generated by gas and electric cooking - grill gas

Abstract objective to measure the concentration of particles less than 100 nm in diameter and nitrogen oxides produced by gas and electric cooking to comment on the possible health hazards of poorly ventilated kitchens.
Methods experiments were conducted with gas and electric rings, grill and oven to compare different cooking methods.
Nitrogen oxides (NOx)
Measured with a chemical luminous ml98 41a NOx analyzer.
Using the TSI 3934 scanning mobile particle size analyzer, the mean quantity concentration and size distribution of aerosol in the 10-500 nm size range were measured.
As a result, high concentrations of particles are produced by gas burning, frying and cooking fatty foods.
The electric ring and grill may also produce particles from the surface.
In experiments where gas combustion is the most important source of particles, the size of most particles is between 15-40 nm.
When Bacon is fried on the gas ring or electric ring, the particles are larger in diameter and the size is between 50-100 nm.
Due to solidification, the smaller particles produced in the experiment become larger over time.
A large amount of NOX is produced during gas cooking;
The four rings in 15 minutes produced a 5-minute peak of about 1000 ppb nitrogen and about 2000 ppb nitrogen oxides.
Conclusion cooking in a poorly ventilated kitchen can lead to a potential toxic concentration of large amounts of particles.
Gas cooking can also produce very high concentrations of nitrogen oxides, which, without extraction and poor ventilation, may reach concentrations that are expected to adversely affect health.
While respiratory effects exposed to NOx may be predictable, recent epidemiology suggests that cardiac effects cannot be ruled out and it is desirable to conduct further investigations into them.
This study was conducted in the laboratory (
Volume 70 m3 with an internal surface area of about 130 m²)in Aberdeen.
No mechanical ventilation was used during the study, and windows were closed during all measurement.
The only potential sources of particles present in the laboratory are gas and rice cookers, both with four rings, an eye level grill and an oven.
The ring of the rice cooker is a closed metal plate.
Nitrogen oxide concentration of nitrogen oxide (NO)and NOx(NO+NO2)
Measured with a chemical luminous ml98 41a NOX analyzer.
NO was obtained by subtracting NO from NOx.
The concentration of Nox is measured horizontally on the surface before the cooker.
The lower detection limit of the display is 0. 5 ppb.
The instrument was calibrated using a certified NOx gas probe.
The data is stored in memory every 5 minutes and downloaded and exported to Microsoft Excel.
The mean quantity and size distribution of aerosol in the size range of 10-3934 nm were measured using the ultra-fine particle TSI 500 scan mobile particle analyzer.
In the 3071A type electrostatic classifier, particles are charged to a known charge distribution via a bipolar charger.
Then, the particles are classified according to their ability to cross the electric field and counted with the 3022A condensate particle counter.
Sampling is carried out through a straight copper tube, which is a method we have previously shown that causes the least loss of particles.
The system is automated through a personal computer, and the data is downloaded and exported in a Microsoft Excel spreadsheet format.
The samples were collected twice.
The 5-minute scanning and scanning mobile granularity measurement system calculates the 5e-minute average period used to process the data.
The Bristol Institute of Industrial Research calibrated the scanning mobile particle size measurement system.
All test and calibration data are obtained through the standard, and its accuracy can be traced back to the National Approved standard laboratory, or has been verified by the instrument, and its accuracy can be traced back to the National Approved standard laboratory, or a recognized value from a physical content.
The particle number concentration is measured in the same place as NOX, at the surface level in front of the cooker.
The UFP concentration in this paper is expressed as the number of particles between 10 nm and 100 nm.
Number of particles with a size range of 10-500 nm (
Divided into 53 size ranges by the scanning moving particle sizer system)
Used to evaluate the range of particle size.
All cooking experiments were conducted between December 1999.
Experiments with gas and rice cookers are the same, comparing the effects of the two cooking fuels.
Every cooking experiment (
Ring, oven and grill)both fatty (bacon)and low fat (
Bread, potatoes or vegetables)
The food was cooked.
Different methods are described in Table 1.
View this table: view inline View pop-up table 1 loss of nitrogen oxides and particles from room air the loss of NOx and UFPs is estimated from the attenuation curve of each pollutant at the end of cooking, and in minutes, the time required for the concentration to drop by 50%.
Loss rate is estimated only when the concentration of contaminants increases significantly during the cooking experiment and the attenuation curve does not show any irregular patterns.
For NOx, the loss comes from the combination of air exchange and surface adsorption.
The loss of 27 UFPs is considered due to exchange with outdoor air, deposition and solidification of the room surface.
Information about the rate of UFPs deposition is not available, but it is assumed that this contribution is relatively small.
The loss of concentration of the number of particles in the condensate depends on the square of the concentration, which means that the UFP concentration is the highest at the end of cooking, which will be relatively more important.
28 the results of statistical analysis of the number of particles and NOx concentration during cooking showed the maximum 5-minute concentration that appeared in the cooking method higher than the baseline concentration.
The baseline concentration was calculated by measuring the mean concentration of eight measurements;
Four before the start of the cooking experiment and four after the end of the experiment, when the rise of particles or NOX returns to a stable level.
In order to compare the number of particles produced in different cooking methods and the concentration of NOx, non-Parameter Mann-
The Whitney test was used. A p value 0.
05 or below is considered significant.
Results the peak concentration of the number of UFPs and the concentration of nox in the cooking experiment of different cooking methods is shown in Table 2.
Generally speaking, cooking with gas produces more particles than electricity.
Table 3 shows the NOx concentration generated during gas cooking.
NOX does not rise when using rice cookers.
When the gas ring is fully opened, the concentration of both UFPs and NOx rises rapidly (fig 1).
The four gas ring combustion caused the UFPs to rise rapidly to an average of 1000 UFP/cm 2, and to an average of about 2000 ppb and about ppb.
The separate gas grill does not produce detectable concentrations of NO or n2.
An electric ring with nothing causes the number of UFPs to increase three of five times;
However, pots with water on the ring have never resulted in an increase in the number of UFPs.
The four electric rings of full power cause UFPs to rise to about 110000 UFPs/m3 in all cases.
View this table: View the inline View pop-up table 2 UFP numbers with a maximum of 5 minutes above the baseline, and the granularity at the peak concentration of each cooking method. View this table: View the nitrogen oxide at the maximum 5-minute concentration of the inline View pop-up table 3 (NO)
And nitrogen (NO2)
Download the new form above the baseline of each cooking method download the concentration of powerpoint figure 1 UFPs, no quantity (NO)
And nitrogen (NO2)
When the four gas rings are fully energized for 15 minutes.
Frying bacon on the gas ring resulted in a maximum peak concentration of 590000 000 UFP/m3 for the number of UFPs.
The peak concentration of UFPs produced by gas fried bacon was significantly higher than that of gas fried vegetables (p=0. 006).
Frying bacon in gas also results in a much higher peak concentration of UFPs than frying bacon on an electric ring (p=0. 006).
Using a gas stove produces more UFPs than using an electric oven.
The gas stove also produced a peak of NOx.
For example, cooking potatoes for 75 minutes will produce a NO2 peak of about 370 ppb without generating a NO2 peak of about 1000 (table 3).
NO and NO gradually rise before the oven closes (fig 2)
No stable concentration was achieved.
However, the particle concentration does reach a platform at approximately 120000 UFP/m3.
Download the new tabDownload figureOpen powerpointFigure UFPs number of people monthly concentration, nitric oxideNO)
And nitrogen (NO2)
Cook potatoes in a gas stove for 75 minutes.
To investigate whether the rise of UFPs and NOx in these short-term experiments is mainly caused by ignition (
Electronic)
Or continue to burn, the four gas rings maintain full power for 2 hours.
After the initial rapid rise of the particle, the concentration decreased.
However, when the gas is still burning, the particles are still produced after the initial rise, because the concentration of the number of particles decreases a lot after the ring is closed (fig 3).
After 75 minutes of opening the ring, nox reached a stable concentration, with a concentration of 2200 ppb and a concentration of 5800 ppb.
In our experiments, NO concentration was always higher than NO during the use of gas rings and ovens.
This lasted at least 2 hours after the cooking experiment (fig 3).
Download the concentration of the new tabDownload powerpoint figure 3 UFPs, no quantity (NO)
And nitrogen (NO2)
When the four gas rings are turned on for 2 hours full power.
In 23 experiments, the loss of nitrogen oxides and particles in room air loss of NOx and UFPs was measured, and both showed a significant increase due to experiments.
Mean value of measurement (SD)
The loss rate of 50% NOx is 67 (27)minutes. The mean (SD)
The 50% loss rate of UFPs is twice that of 30: 00 (10)minutes.
The reason for the high turnover rate of UFPs may be the solidification of particles.
28 particle size the peak particle size described below is the UFP number distribution pattern measured during the experiment (table 2).
The peak diameter of the particles produced by the gas ring separately and the particles produced by boiling water on the gas is within the range of 15-40 nm.
For particles generated when the gas grill is opened separately and the electric ring is opened without a pot, the peak is within the same size range.
When Bacon is fried on a gas or electric ring, the particles are large and the size range of most particles is 50-100 nm.
After the gas ring is opened, the maximum number of particles is within a very fine size range, but then the particles become larger over time.
Figure 4 shows the particle size range generated by the four gas rings opening 2 hours.
5, 15 and 30 minutes after the ring was opened, the peak concentration was 15, 30 and 40 nm diameter, respectively.
Therefore, when the gas ring Burns, the particles grow up to a peak of about 50-70 nm.
The only case where particles do not grow over time is in some bacon frying experiments, up to 80 nm when the initial particle size is already relatively large.
The most reasonable explanation for this finding is to solidify very small particles into larger reunions.
Download figureOpen in the new tabDownload powerpoint figure 4, and when the four gas rings are fully powered on for 2 hours, the particle size is distributed at different times.
Many epidemiology studies have shown a link between exposure to outdoor air particle pollution and poor health.
There is a similar relationship with n2.
In both cases, these associations appear to exist even in cases where concentrations are very low in traditional toxicology terms.
Also, although most people spend at least 90% of their time indoors, they still happen.
These findings raise two important questions.
First, if these associations are the cause, it is expected that other sources of particles and NOx will affect the health of the exposed population.
So we asked ourselves what concentration might appear in the kitchen relative to the outside kitchen.
Secondly, if total exposure to toxic substances is an important determinant of the impact, then part of it may occur indoors.
Further refinement of epidemiology studies may require modeling of individual exposures, so it is necessary to understand the contribution of indoor exposure to these exposures.
Therefore, this study is also planned as a first step in this modeling and as part of the study to determine whether the particles and gases produced indoors have the same toxicity as outdoors.
We have found that many UFPs are produced not only by gas combustion, but also by heating plates and grills.
Cooking with electricity or gas has the potential to increase the amount of particles, mainly by frying and Grilling fatty foods and by using fat frying.
The particles produced by gas combustion are smaller than those produced by cooking fatty foods.
Two recent studies have also investigated the concentration of indoor particle numbers.
Wallace29 identifies the gas stove, gas stove and electric toaster as the most important source of UFPs.
Abtet al30 concludes that cooking, including barbecue or baking, baking and grilling, mainly contributes to particles 20-500 nm in diameter.
It was also found that frying within this size range will release the particles.
Although no experimental studies have been conducted on human exposure to indoor UFPs, indoor concentrations are as high as those when outdoor air pollution is severe, when people are shown to have an impact on health.
Tiny particles produced during gas combustion may be carbon.
We have shown that the original very small particles may gather, so the overall number will decrease over time.
When the electric ring is opened without a pot, small particles are also produced.
These may be the substance burned from the ring, the metal of the ring itself, or both.
This discharge does not occur when a pot of water is placed on the ring, and we assume that this is the result of the heat that the ring is brought into the water so that the material on the ring does not burn off.
It is not surprising that any activity related to the heating of fatty foods results in high concentrations of particles. Although the higher temperatures that the gas quickly reaches seem to be the reason for this cooking method to rise.
Siegmann et al. measured the size distribution of aerosol produced by heating rapeseed oil at different temperatures.
They found that the diameter and quantity concentration increased as the temperature increased.
The average drop diameter is 30 nm at 223 °c and 100 nm at 256 °c.
The number of particles with a diameter less than 100 nm increases rapidly with the increase of temperature, and the number of particles released by oil at 256 °c is about twice that of oil at 223 °c.
Our study does not represent personal exposure to people working in the kitchen, as sampling occurs where the head is highly fixed in front of the cooker, and the concentration measured here may overestimate the chef's exposure.
In addition, during the experiment, we did not actively ventilate the laboratory, nor did we have a draft fan.
However, when frying bacon and frying vegetables, the concentration measured in the cooking experiment should be close to the actual exposure of one person to cook.
At present, the UK ambient air no 2 standard is mainly based on the human experimental exposure study, which shows that at a concentration of about 200 ppb, it has a subtle impact on inflammatory markers and has increased
32 epidemiology studies have shown an impact on the population at lower concentrations, and a recent panel study has shown that vulnerable people with heart disease may have an environmental concentration of less than 40 ppb
If NO2 or it can be imagined that NO is responsible for these effects, a kitchen with a relatively high NOX concentration may be an important source of exposure.
Several studies have investigated the concentration of no 2 in the home, and internal sources are often the main cause of personal exposure, and most importantly environmental tobacco smoke and gas cooking. 33-
In this study, we have shown that the use of gas rings and ovens can produce a large number of no 2, and of course, this concentration can have adverse effects on humans, for example, by increasing sensitivity to allergens and causing airway inflammation.
39 in the process of gas cooking, the background concentration increased sharply, and the short-term indoor concentration was higher than the outdoor concentration.
In Aberdeen, during the period from 1999, the highest external NO2 and NO concentrations per hour were 63 ppb and 357 ppb, respectively, which were rarely achieved.
The concentration of NO2 was monitored at 83 country network sites throughout the United Kingdom, with the highest level of 99 in 1998.
At a roadside site in Glasgow, the eighth percentage value of the hourly concentration is 140 ppb.
We found that when the two gas rings were turned on for 15 minutes, the concentration of NO2 per hour exceeded 300 ppb.
In contrast, in the study of Strand et al, the concentration of 260 ppb lasted for 30 minutes and was associated with an increase in Allergen inhalation response.
39 other short-term studies have shown similar results.
4041 it is well known that nitrogen oxides in outdoor air disappear rapidly due to the formation of n2 in reaction with ozone.
However, indoors, we found that the concentration of NO exceeded the concentration of no2 for at least 2 hours after our experiments on gas stoves and ovens (fig 1 and 2).
Suppose diarrhea by Farrow et al (
This was significantly associated with no 2 concentration)
In fact, it may be due to exposure to a high concentration of NO.
It is even possible that by affecting the natural production of NO by endothelial cells, long-term exposure to NO may lead to some Epidemiology-related cardiac effects associated with NO;
No further study of this hypothesis has been made.
In addition to carbon particles and NOx, cooking is also related to the production of fat particles, which may themselves be harmful to health.
31 several studies have shown that the aerosol in edible oil has mutation-causing and genetic toxicity, and 44 may be the cause of an increased incidence of lung cancer in women in Taiwan and China, and exposure to cigarette smoke is not entirely explained.
4546 recently, Ko et al released details of 131 non-cooking conditions and habits
Cases of smoking events in women newly diagnosed with lung cancer, found that with the increase in the number of food cooked every day, the risk of lung cancer increased, no use of a ventilator, before they started cooking, waiting for smoke to be discharged from the oil.
In our study, we found that UFPs generation for gas cooking would be higher, probably because the oil was exposed to higher direct temperatures.
In conclusion, cooking in a poorly ventilated kitchen can produce potentially toxic particle concentrations.
If gas is used, a high concentration of NOx will also be produced, and if not fully extracted, it may pose a real risk to the breathing and heart health of the exposed population.
It is necessary to further study the relationship between indoor exposure to NOx and cardiac events.
Thanks to the UK Department of Health for their financial support for the study and to Professor R Maynard for his encouragement.
We also thank Professor L Wallace for his helpful comments.
The MD received funding from the British Lung Foundation.
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