The writing process for the majority of Metallicaâs albums have followed the same process. A large slew of guitar riffs written primarily by James Hetfield, sometimes Kirk Hammett, and rarely the bandâs bass player, (that now being bass virtuoso Robert Trujillo) are reviewed and selected.
1 Delhi is most polluted city in the world in PM2.5 concentrations. 2  Half of the top 20 most polluted cities were in India, according to data.  PM2.5 is considered most harmful to health.
Seven of the most polluted cities in America are in one single state. Douglas McIntyre of 24/7 Wall Street looks at the ten cities with the worst air pollution. More than 138 million people, nearly 44% of the U.S. population, live in areas where air pollution reaches dangerously high levels during parts of the year.