The Impact of Temperature on PM Emissions while Cooking

What is particulate matter?

Particulate matter (PM) is an air pollutant that is made of very small solid or liquid particles that are temporarily suspended in the air (Baird and Cann 119). To begin, it is important to recognize the adverse health effects that result from exposure to PM in the atmosphere. Risks include lung damage and respiratory issues, as well as heart disease and irregular heartbeats (Kim at al. 137). It has been determined that 2.1 million deaths are caused by PM2.5 each year (Kim et al. 136). Undoubtedly, PM is a very hazardous air pollutant that needs to be closely monitored. Understanding where PM comes from can ensure that public health measures are taken in order to reduce these health risks.

Particulate matter varies in size and chemical composition, and it is classified in terms of the diameter of the particulates. PM10 has a diameter of less than 10 µm, while PM2.5 has a diameter of less than 2.5 µm. Sources of PM emissions have been identified that are both natural and anthropogenic. Some natural sources of PM10 include dust storms and pollen released from plants, while a common anthropogenic source is land cultivation (Baird and Cann 121). Unlike PM10, PM2.5 is a secondary pollutant, meaning it is formed by chemical reactions between other gases. PM2.5 is often produced from vehicle break ware, combustion of fossil fuels, and vehicle emissions (Baird and Cann 121). Although all the above-mentioned sources originate outdoors, there are a multitude of indoor activities that emit hazardous PM levels as well.

Indoor sources of PM

Common indoor PM sources include cleaning products, candle and incense burning, smoking, and cooking (Habre et al). Gaining knowledge about indoor sources of PM is crucial since many people spend copious amounts of time indoors. To further advance the study of indoor PM, we wanted to explore how cooking impacts PM emissions. Previous studies have shown that certain types of cooking result in higher PM emissions than others. Specifically, frying on a stovetop produces higher PM emissions than cooking in an oven. However, we were unable to find previous research on how temperature impacts the PM emissions while frying on a stovetop. So, we decided to focus our study on this question.

The goal of our research project was to determine how different temperatures affect PM emissions while frying different foods. Understanding how cooking temperatures impact indoor air quality is important because it can reduce the adverse health effects of PM inhalation. If the public is made aware of what causes high PM emissions while cooking in their homes, they can be educated on ways to reduce these emissions. In our study, the two food types we chose to compare were a hamburger patty and a zucchini. We predicted that frying foods at higher temperatures would result in higher PM emissions compared to frying at lower temperatures. We determined that this would be related to higher volatility at higher temperatures. This means the moisture in the food will vaporize more readily, resulting in higher PM concentrations.

Experimental methods

In order to test our hypothesis, my lab partner and I used an Atmotube air quality monitoring device to measure the air while cooking on a gas stovetop at various temperatures. We conducted 8 experiments in total to test how different temperatures impacted the PM emissions while frying each food. The burger and zucchini were each cooked at 4 different temperatures: 250 F, 300 F, 350 F, 400 F. Canola oil was first added to a frying pan, and the temperature was monitored using a probe thermometer.

Each cooking event was timed for 5 minutes once the oil reached the desired temperature for that experiment. The Atmotube recorded PM measurements every minute, so we obtained 5 measurements for each cooking event. We recorded data until we saw the PM levels start to decrease. Moreover, before each cooking event we measured a 5-minute control to determine what the PM levels were in the apartment before any cooking was done. This ensured that PM concentrations returned to control levels before starting each experiment. Lastly, we determined the volume of the room in which the cooking events took place and used this to calculate the PM emission rates. This allowed us to determine the total aerosol production during the experiments and analyze our results effectively.

Our findings

From our study, we found that cooking at higher temperatures resulted in higher PM10 and PM2.5 emissions for both the burger and the zucchini. Figures 1 and 2 show that emission rates increased as temperature increased for PM10 and PM2.5. Highest emission rates were observed at 400 F and lowest emission rates were observed at 250 F. This was true for both the meat and vegetable. However, the results were inconclusive regarding the impact of different food items on PM emissions. At 350 F, the emission rates of the zucchini were greater than the emission rates of the burger. Contrarily, at 400 F, the emission rates of the burger were greater than those of the zucchini. This data is summarized below in Figures 1 and 2.

Figure 1. PM 2.5 emission rates per temperature and food type. 

Figure 2. PM 10 emission rates per temperature and food type. 

The results of our study support our hypothesis that frying both meat and vegetables at higher temperatures will result in higher PM levels. This is supported by the data showing that emission rates were lowest for cooking events at 250 F and highest for cooking events at 400 F, providing evidence that PM levels rise as temperature rises. This trend could be related to the moisture in the food vaporizing faster when the food is fried at higher temperatures. Therefore, cooking at lower temperatures for longer amounts of time could potentially decrease the health risks that accompany frying foods at high temperatures.

Unanswered questions

The main question that remains unanswered from our study is how different types of foods impact the emissions of PM, since our results comparing the meat and vegetable were inconclusive in this regard. Further studies comparing different food types at different temperatures will be useful to determine the effect of food types on PM emissions. We also considered how the effect of food burning at higher temperatures could be related to higher PM emissions. In order to determine if there is a direct correlation between food burning and PM emissions, further studies need to be conducted.

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