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.
Global air pollution: what is the most polluted country and city in the world? The World Health Organisation reveals pollution levels around the globe. Air pollution figures are gathered all over the globe, but it takes some serious effort to bring them all together so that countries and cities can be compared.