Air Quality Alert: Arizona's Pollution Problem

Arizona, the 14th most populous state in the US, has a diverse economy with sectors including transportation, healthcare, higher education, manufacturing, and construction. The state's large population, coupled with its various industries, can contribute to higher levels of air pollution. While some cities in Arizona have moderate to good air quality, others face significant pollution issues, particularly Phoenix, which has been ranked among the worst cities for air pollution in the country.

Phoenix's air quality

Phoenix, Arizona's capital and most populous city, has been facing challenges with its air quality in recent years. With a population of nearly 1.7 million people, it is the fifth most populous city in the United States. The city's air quality is primarily affected by its large population and the subsequent anthropogenic activity, including vehicular emissions, which contribute to high levels of nitrogen oxides and organic substances. These emissions react with sunlight to form ozone, a gas pollutant and the greatest challenge to Phoenix's air quality.

While Phoenix experiences cleaner air during the summer months, the winter months, especially November and December, see a significant increase in pollution levels. Temperature inversions during winter contribute to higher AQI levels, with an average of 2.5 times higher AQI than in the summer. The Clean Air Act of 1970 and its subsequent amendments in 1990 have helped improve Phoenix's air quality over the years. However, recent reports indicate a decline in air quality since 2016, with an increase in unhealthy days of ozone and particle pollution.

The American Lung Association's "State of the Air" report for 2019 ranked Phoenix 7th in the nation for ozone pollution and 10th for short-term particle pollution. The report also revealed that Phoenix experienced more unhealthy days of high ozone levels compared to the previous year. The year 2020 saw a further decline in air quality, with Phoenix ranked as one of the worst cities in the country for year-round and short-term particle pollution. The COVID-19 restrictions that year led to a significant improvement in air quality as people stayed home and drove less.

Despite these challenges, Phoenix's air quality is rated as "'good'" on annual and monthly averages, with an AQI score of less than 50. However, the city still experiences unhealthy ozone and PM2.5 days. From 2016 to 2018, there was a weighted average of 46.5 days of unhealthy air, resulting in Phoenix failing to attain the air pollution standards for ozone and PM2.5. The months of May and June are typically the cleanest, while November and December tend to have the worst air quality.

The air pollution in Phoenix has various health implications for its residents. Sensitive groups, such as children, older adults, and people with asthma, are particularly vulnerable to the effects of ozone-polluted air, which can trigger asthma attacks, heart attacks, and strokes. The tiny particles in the air can lodge deep in the lungs, causing serious health issues and even leading to premature death. Therefore, it is crucial for Phoenix residents to stay informed about the air quality and take necessary precautions to protect their health.

Meteorological factors

Arizona's air pollution is influenced by a range of meteorological factors, which interact with human activities to produce varying levels of pollution across the state. The state's diverse climate, from desert regions in the south to forested areas and snowfall in the north, presents unique challenges for air quality.

One significant meteorological factor is temperature. Warmer temperatures brought by climate change increase the likelihood of ozone formation and make it harder to reduce ozone pollution. This is particularly relevant for Phoenix, which has been ranked among the worst cities for air pollution in the country. The American Lung Association's 2019 report found that Phoenix experienced more unhealthy days with high ozone levels and an increase in particle pollution.

Intense heat, as well as extreme cold, can also impact human activities and contribute to air pollution. For example, during colder months, the demand for heating increases, leading to higher emissions from power plants and other industrial sources. This interplay between meteorological factors and human activities can exacerbate air pollution levels in certain areas.

Arizona's geographical features, such as its mountainous regions and varying elevations, can also influence air pollution dispersion and concentration. Low-lying areas, particularly around freeways and airports, tend to experience higher levels of pollution, affecting nearby communities. These meteorological and topological factors contribute to the complex dynamics of air pollution in Arizona, requiring constant monitoring and efforts to improve air quality for the well-being of Arizonans.

Anthropogenic activity

Energy consumption, including heat and electricity generation, is the largest contributor to greenhouse gas emissions. Coal-fired power plants, in particular, emit significant amounts of mercury into the atmosphere, impacting the speciation and concentration of mercury emitted. Additionally, urban traffic and road-related activities contribute to heavy metal pollution, with abrasion of tires, fuel residues, and fluid leakage depositing metals onto roads and sediments.

Agricultural practices also play a role in anthropogenic air pollution. The intensification of agriculture on bare soil accelerates the natural suspension of dust, leading to the dispersal of pollutants. Desertification of semi-arid lands further exacerbates this issue. Moreover, the burning of biomass, such as forest fires, which was once a natural process, is now largely driven and controlled by humans, impacting air quality.

Other anthropogenic sources of air pollution include cigarette and e-cigarette smoke, as well as industrial emissions. Vinyl chloride, a hazardous substance found in the environment, is attributed to human activities, with manufacturing plants and hazardous waste sites being key contributors. To address these issues, many countries have implemented emission reduction strategies, such as cap and trade programs, which incentivize companies to limit their pollution output.

Vehicular emissions

Arizona's large population of over 7 million people means that there are hundreds of thousands of personal vehicles like motorbikes and cars on the road at any given time. This leads to vehicular emissions, which are a significant source of air pollution in the state. Vehicle emissions contribute to increased levels of air pollution, including man-made ozone and particulate matter (smoke and dust).

The American Lung Association's 2019 "State of the Air" report found that Phoenix, Arizona's most populous city, had earned poorer rankings for the nation's most widespread air pollutants. The report ranked Phoenix 7th for year-round particle pollution and 10th for short-term particle pollution. The report also showed that Phoenix experienced more unhealthy days of high ozone levels and an increase in particle pollution.

While Phoenix's air quality on annual and monthly averages is rated as "'Good," with an Air Quality Index (AQI) score of less than 50, the city still experiences a number of unhealthy ozone and PM2.5 days. From 2016 to 2018, there was a weighted average of 46.5 days of unhealthy air, resulting in Phoenix failing air pollution attainment for ozone and PM2.5.

Vehicle emissions are a major contributor to air pollution in Phoenix, with data from the federal Environmental Protection Agency (EPA) and Arizona Department of Environmental Quality (ADEQ) showing that most air pollution comes from this source. To address this issue, Arizona has implemented an emissions inspection program for vehicles, requiring them to undergo tests like the curb idle test, loaded test, and onboard diagnostic check to ensure they meet health-based standards and reduce pollution levels.

Population size

Arizona has a population of approximately 7.27 million people, making it the 14th most populous state in the US. The state's population size can contribute to the issue of air pollution, as a larger number of people typically results in higher pollution levels. Phoenix, the state's capital and most populous city, had an estimated population of almost 1.7 million people in 2019, making it the fifth most populous city in the US.

The large population of Arizona means that there are hundreds of thousands of personal vehicles on the road at any given time, contributing to vehicular fumes and emissions. The state's economy is largely focused on sectors such as transportation, manufacturing, and construction, which can also negatively impact air quality. The diverse economic landscape contributes to air pollution through mass manufacturing, mining, and exporting goods.

In addition to the overall population size, certain demographic groups are more vulnerable to the effects of air pollution. This includes children, older adults, and people with pre-existing lung diseases such as asthma and COPD. People of colour and individuals from low-income communities are disproportionately affected by air pollution, facing higher health risks.

While Arizona has made some progress in improving air quality, particularly in the Phoenix area, it continues to face challenges in addressing dust, smoke, and ground-level ozone concentrations. High population density, coupled with the state's diverse economic activities, contributes to air pollution levels in Arizona.

To mitigate the impact of population size on air pollution, Arizona has implemented various measures. These include promoting public transit, encouraging the use of electric vehicles, and regulating gasoline blends. Additionally, policies targeting oil and gas emissions and community involvement in reducing emissions from nearby pollution sources are also being explored.

Frequently asked questions