Over the past month, my team and I conducted research on the amount of air pollution produced by both cigarettes and cigarillos, a type of cigar. Specifically, we aimed to test the amount of PM 2.5 produced. PM stands for particulate matter and the 2.5 signifies the size of the pollutants that we were measuring in this case it was any pollutants that have a width smaller than two and a half microns. For comparison, one human hair has an average width of 70 microns. Even though these pollutants are extremely small they have great impacts on our health. Overall, air pollution leads to 4.6 million premature death annually according to the World Health Organization. In particular, PM 2.5 is extremely dangerous as its small size allows it to travel deep into our respiratory tract and even into our blood. This can lead to worsened asthma, chronic bronchitis, heart disease, pneumonia, and even premature death. We decided to study cigarette and cigarillo emissions as they were one of the leading sources of PM 2.5 emissions at the turn of the century. Even if a person does not smoke, they can still be exposed to dangerous pollutants through secondhand smoke. To check out more information on the harmful effects of PM 2.5 make sure to read the brief news article linked below.
Figure 1: Depiction of how PM 2.5 can enter the body and affect human health. Courtesy of the Utah Department of Health
Through our study, we were working to determine which tobacco product, cigarettes, or cigarillos, produced more PM 2.5. Based on our research we developed a hypothesis stating that cigarettes, due to chemical additives, would produce more PM 2.5 than cigarillos. This is because cigarettes contain tobacco and other additives such as ammonia, while cigarillos claim to just be tobacco. To be able to answer this hypothesis is extremely important because over the past twenty years while cigarette consumption has declined, cigar and cigarillo consumption has greatly increased. With few studies conducted on the effects of cigarillos on PM 2.5 emissions, this is a grave concern as we do not know how this is affecting PM 2.5 and therefore public health. By answering our hypothesis, we will also be able to determine which tobacco product (cigarettes or cigarillos) produces less PM 2.5. Additionally, we can establish a safe distance from cigarettes or cigarillos that can limit exposure to harmful PM 2.5 through secondhand smoke.
To answer our hypothesis, we designed an experiment to test the PM 2.5 emissions from both cigarettes and cigarillos. We conducted our experiment outside as it would better represent real-world conditions as most nonsmokers interact with secondhand smoke outdoors. We measured PM 2.5 using an Atmotube PRO air sensor set at five different distances (1ft, 3ft, 5ft, 7ft, and 10ft). A cigarette when then be lit at the first distance and allowed to burn for five minutes while PM 2.5 data was recorded by the sensor. After the five minutes, we would allow for a three-minute rest period to allow air quality to resume its normal levels. Then we would proceed to light a new cigarette at the next distance for five minutes and repeat the process until both cigarette and cigarillo data was recorded. Testing occurred over a two-week period and changes were made between weeks one and two to account for factors affecting our data. For example, we determined that wind was the biggest factor in affecting the concentration of PM 2.5. Therefore, for the second week of data collection, we changed locations to an ally and used a fan to control the air movement towards our air sensor. This allowed our results to not only be more accurate but be more applicable to the local community as San Diego has a constant ocean breeze.
Figure 2: Left: Week 1 experimental set up in an open-air environment.
Right: Week 2 experimental set up in a sheltered alley.
Analyzing our data from cigarettes we saw the greatest concentration of PM 2.5 when the cigarette was 1ft away from the sensor, as the distance from the sensor increased the concentration of PM 2.5 also decreased for the 3, 5, and 7 ft measurements. Interestingly, at 10ft the concentration of PM 2.5 increased once again. This is most likely due to an experimental design error in which the fan was kept at a constant distance of 11ft from the sensor. This means as the cigarette moved further away from the sensor it moved closer to the fan. Our team believes that when the cigarette was at 10 ft the strong air movement from the fan caused more of the smoke (and therefore PM 2.5) to reach the sensor. Looking at the cigarillo data we see similar results. Concentrations of PM 2.5 decrease as you move away from the sensor, but once again at 10ft concentrations of PM 2.5 increase most likely due to the proximity to the fan.
Figure 3: Summary of data collection taken over two weeks depicting the average PM 2.5 for both cigarettes and cigarillos over multiple distances.
The findings from our data reveal our initial hypothesis was supported for 1, 3, and 5ft. For these distances, PM 2.5 emissions were greater for cigarettes than for cigarillos. Beyond 5ft (7ft and 10 ft) our findings showed that cigarillo PM 2.5 emissions were greater than cigarettes, which would prove our hypothesis wrong. However, due to our experimental error, we conducted a comparison between our collected data and other related studies and found that cigarette PM 2.5 emission is indeed greater than cigarillo PM 2.5 emissions. This shows how even with our finding our hypothesis was ultimately supported, cigarettes produce more PM 2.5 than cigarillos. Additionally, we were able to determine that a 10 ft distance from someone who is smoking is sufficient to limit harmful PM 2.5 exposure. From this experiment, there are still some unanswered questions including the effect of smoke density on the dispersion of air pollutants. Furthermore, it would be interesting to find out if the increase in cigarillo consumption is increasing overall PM 2.5 from tobacco products.