Background

This dashboard uses daily Air Quality Index (AQI) data for California cities included in the top5_cities.rds dataset. The data represent daily AQI measurements and corresponding population estimates for multiple California cities over several years. For this assignment, I focused on the five cities with the highest population-weighted mean AQI to understand which communities experience the highest pollution burden and how daily air quality varies across these locations. My guiding question was: How does air quality differ across the most polluted cities in California, and which cities face the greatest average burden? This information is important for public health professionals and policymakers because consistently higher AQI levels signal communities that may face disproportionate exposure to harmful air pollutants, informing decisions around environmental monitoring and resource allocation.

Data source: top5_cities.rds (Week 10 AQI teaching dataset).

Results

Across the five cities with the highest pollution burden, Riverside had the highest population-weighted mean AQI, followed by Los Angeles, Bakersfield, and Fresno, while Bishop had the lowest mean values among this high-burden group. The boxplot (Figure 1) highlights wide variability in daily AQI values, including extreme high-AQI days likely driven by wildfire events, particularly for Riverside and Los Angeles. In contrast, cities like Bishop exhibit lower median AQI and narrower distributions. The bar chart (Figure 2) summarizes these patterns by showing that Riverside experiences the highest average AQI, reinforcing that some communities consistently face poorer air quality. Together, these visualizations illustrate both the day-to-day variability in AQI and the overall pollution burden across California’s most affected cities.

Accessibility notes

• Figure 1 alt text: Boxplot of daily AQI values for Bishop, Fresno, Bakersfield, Los Angeles, and Riverside, showing medians, interquartile ranges, and high-AQI outliers for each city.

• Figure 2 alt text: Horizontal bar chart showing population-weighted mean AQI for Bishop, Fresno, Bakersfield, Los Angeles, and Riverside, ordered from lowest to highest average AQI.

Figure 1. Daily AQI Distributions (Boxplot)

Figure 2. Average Pollution Burden: Mean AQI by City