Plot 4

Plot 4 created by plot4.R script.
Plot 5

Plot 5 created by plot5.R script.
Plot 6

Plot 6 created by plot6.R script.
Plot2 Script

Script creates a bar plot to answer: Have total emissions from PM
decreased in the Baltimore City, Maryland ( fips == "24510") from 1999
to 2008? Use the base plotting system to make a plot answering this
question.
Plot3 Script

Script creates a bar plot to answer: Of the four types of sources
indicated by the type ( point, nonpoint, onroad, nonroad ) variable,
which of these four sources have seen decreases in emissions from
1999–2008 for Baltimore City? Which have seen increases in emissions
from 1999–2008? Use the ggplot2 plotting system to make a plot answer
this question.
Plot4 Script

Script creates a bar plot to answer:  Across the United States, how have
emissions from coal combustion-related sources changed from 1999–2008?
Plot5 Script

Script creates a bar plot to answer: How have emissions from motor
vehicle sources changed from 1999–2008 in Baltimore City?
Plot6 Script

Script creates a bar plot to answer: Compare emissions from motor
vehicle sources in Baltimore City with emissions from motor vehicle
sources in Los Angeles County, California ( fips == "06037"). Which city
has seen greater changes over time in motor vehicle emissions?