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Title: Air Quality Trends in Top California Cities
Subtitle: A dashboard for PHW251B students
Data source: top5_cities.rds (AQI data for 5 cities, 1980–2022)
Background: This dashboard explores air quality (AQI) trends in five major U.S. cities over four decades (1980-2022). The dataset includes daily AQI measurements, city population, and location data. The research question is: How does AQI vary over time in these top cities? Monitoring these trends is important for public health because air pollution affects respiratory and cardiovascular health. The dashboard allows viewers to observe long-term trends, identify spikes (e.g., wildfire season), compare variability across cities, and examine the relationship between city population and air quality.
Results: Figures 1 and 2 show how the average Air Quality Index (AQI) varied in the selected cities from 1980 to 2022. Overall, AQI values fluctuate over time. Riverside and Los Angeles exhibit a downward trend, consistent with improved air quality from environmental awareness and management efforts. Fresno and Bakersfield remain relatively stable, while Bishop shows a slight upward trend. Despite these differences, AQI distributions are generally similar across cities, with large outliers likely reflecting episodic events such as wildfires. Cities with higher population density tend to have higher average AQIs, suggesting urban activity and emissions contribute to poorer air quality. Visualizing these trends helps public health practitioners monitor air quality, prioritize interventions, and communicate risk to communities, supporting the research question by highlighting both long-term trends and episodic variability.

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