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.
Several of the most polluted cities are located in or near the Central Valley in California. In addition to the wildfires and drought that have affected the region, the area's natural topography exacerbates the pollution problem.ore 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. While exposure to low quality air has declined in recent years, some cities still experience alarming levels of pollution.