Proposal Requirement 3 Example: Photocatalytic Epoxy Asphalt for Pollutant Degradation

Writer: Bonnie Chen

Instagram: @bonniechens


Summary of Significance

In 2019, the United States emitted 8,950,000 tons of NOx gases, with over half of the amount coming from highway and off-highway vehicles (National Tier 1 Caps 2020). Although the amount of NOx emissions have dramatically decreased from past years due to proactive measures, more research must be done to mitigate its harmful effects. This study aims to explore a practical solution to post-combustion air pollution due to traffic, specifically targeting NOx pollution. NOx pollution caused by fuel combustion in the transportation sector leads to a variety of issues, including acid rain, smog, and the aggravation of respiratory illnesses(Nitrogen Oxides Control Regulations | Ground-level Ozone | New England | US EPA 2019).

Acid rain occurs when NOx particles react with “water, oxygen, and other chemicals,” forming nitric acids (What is Acid Rain? 2020). Due to these acids, the pH levels of soils that come in contact with them are lowered, thereby decreasing the number of nutrient cations and increasing the amount of toxic heavy metals in the soil, affecting soil fertility both agriculturally in and forests (Singh & Agrawal, 2008). When acid rain is precipitated over freshwater bodies, they can increase concentrations of hydrogen ions, leading to a decrease in biodiversity, as many species such as crustaceans rely on a specific aquatic environment with a pH of over 6. For example, one study anticipates a 20% decrease in the crayfish population at the Pinail reserve due to freshwater acidification (Beaune et al., 2018). Any disruption of the quantity of a species in an ecosystem can further cause a chain reaction among the organisms that rely on the species as a food source or whose populations are kept in control by the species (Chadwick et al., 1987). Not only does acid rain affect nature, but it also affects man-made structures. Acid deposition corrodes materials like metal, paint, and stone (Effects of Acid Rain 2020), risking historic monuments and resulting in increased maintenance costs (Impacts of Acid Rain on Buildings).

Another consequence of NOx emission is the nutrient pollution of coastal waters. While nitrogen is vital to ensuring the growth of beneficial algae, in larger amounts induced by NOx pollution, it can cause algal blooms, which can reduce the oxygen concentration to a level below the amount that can sustain all of the aquatic life, leading to “illnesses in fish and the death of large numbers of fish.” These algal blooms also promote harmful bacterial growth that can cause illnesses in people that drink the water or eat contaminated fish or shellfish (Nutrient Pollution 2019).

NOx also has a more direct effect on human health. It exacerbates existing respiratory illnesses, like asthma, when inhaled in the short term (Integrated Science Assessment (ISA) For Oxides of Nitrogen – Health Criteria 2016). Furthermore, NOx particles penetrate deeply into the lungs, which “induc[es] respiratory diseases, coughing, wheezing, dyspnea, bronchospasm, and even pulmonary edema when inhaled at high levels” (Manisalidis et al., 2020). High levels of NOx exposure in the long term can even lead to chronic lung disease and impair the sense of smell (Chen et al., 2007). Also, NOx particles have been shown to create secondary pollutants that form smog and reduce visibility (Wang et al., 2019), specifically reacting with volatile organic compounds (VOCs) when under sunlight to create tropospheric ozone, also known as ground-level ozone (Ground-level Ozone Basics 2020). Although some more grave consequences are shown to be correlated with air pollution such as “cardiovascular effects, diabetes, poorer birth outcomes, premature mortality, and cancer” do not have decisive evidence showing that they can be caused by NOx particles alone, it has already been proven to pose risk to the respiratory system even with short-term exposure (Integrated Science Assessment (ISA) For Oxides of Nitrogen – Health Criteria 2016), highlighting the importance of reducing NOx pollutant concentration in the air.


To begin, the author makes the goal of her proposal very clear so that any readers can see that there is a clear and necessary purpose for the proposal. The issue targeted is specific, which shows to the proposal reader that solving the problem is feasible and realistic, rather than being a lofty or idealistic goal. Having a specific issue also helps to find related research and to have a backbone to center the rest of the writing around.

When writing an Envision proposal, the significance of the proposed technology or study will be shown in the writing of component 3, which is the summary of the significance of the targeted problem. Therefore, it is important to show the impact and scope of the issue through facts, statistics, and other scientific literature in this part of the writing. The author does well to first show that the issue at hand is relevant by talking about NOx emission levels before diving into the impacts. She then elaborates on each of the major impacts of the issue in logical sections, further developing the significance of the issue. In order to do so, she incorporates examples like when she lists respiratory illnesses or the example of predicted crayfish population reduction. She includes many citations, with each claimed consequence of the problem being supported by previously published literature or a trustworthy organization.

While the author did well to show the importance of the issue as well as support it with reliable research, she could have talked about some of the impacts with less ambiguity. For example, there are a few places where she uses adjectives to describe the situation instead of quantifying it, like when she says, “in larger amounts induced by NOx pollution.” Instead, she could have talked about the amount of NOx pollution so that the reader is more familiar with the degree to which NOx pollution must be reduced to no longer be a threat, making the goals and the practicality of the proposal more clear.


Beaune, D., Sellier, Y., Luquet, G., & Grandjean, F. (2018). Freshwater acidification: an example of an endangered crayfish species sensitive to pH. Hydrobiologia, 813(1), 41–50.

Chadwick, M. J., Highton, N. H., & Lindman, N. (1987). The Effect of Coal Utilization Emissions on Natural and Man-managed Terrestrial and Freshwater Ecosystems. Environmental Impacts of Coal Mining & Utilization, 282–318.

Chen, T. M., Gokhale, J., Shofer, S., & Kuschner, W. G. (2007). Outdoor air pollution: nitrogen dioxide, sulfur dioxide, and carbon monoxide health effects. The American journal of the medical sciences, 333(4), 249–256.

Environmental Protection Agency. (2019, February 4). Nutrient Pollution. EPA.

Environmental Protection Agency. (2019, October 10). Nitrogen Oxides Control Regulations | Ground-level Ozone | New England | US EPA. EPA.

Environmental Protection Agency. (2020, April 27). National Tier 1 Caps.

Environmental Protection Agency. (2020, July 13). Ground-level Ozone Basics. EPA.

Environmental Protection Agency. (2020, May 12). What is Acid Rain? EPA.

Environmental Protection Agency. (2020, May 4). Effects of Acid Rain. EPA.

Impacts of Acid Rain on Buildings. Air Quality.

Manisalidis, I., Stavropoulou, E., Stavropoulos, A., & Bezirtzoglou, E. (2020). Environmental and Health Impacts of Air Pollution: A Review. Frontiers in public health, 8, 14.

Singh, A., & Agrawal, M. (2008). Acid rain and its ecological consequences. Journal of environmental biology, 29(1), 15–24. U.S. EPA. Integrated Science Assessment (ISA) For Oxides of Nitrogen – Health Criteria (Final Report, 2016). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-15/068, 2016.

Wang, J., Wu, Q., Liu, J., Yang, H., Yin, M., Chen, S., Guo, P., Ren, J., Luo, X., Linghu, W., & Huang, Q. (2019). Vehicle emission and atmospheric pollution in China: problems, progress, and prospects. PeerJ, 7, e6932.