British research from 2012 shows that more people worldwide die from exposure to particulate matter indoors than from exposure to particulate matter outdoors.
The WHO has released data on levels of particulate matter in 3,000 urban areas in 103 countries around the world, highlighting what it described as the "greatest environmental risk to health", responsible for more than 3 million premature deaths worldwide ever year.
Restore London's air quality is one of Sadiq Khan's promises as the new mayor of London
Millions of Londoners breathed air contaminated with record-breaking levels of a harmful pollutant for which
there is no known safe exposure this month.
According to the National Air Duct Cleaners Association an average home collects as much as 40 pounds of dust, dirt and allergens in a year. This is alarming given that this dirt contains about 40,000 dust mites and hosts unhealthy bacteria, mold and fungi.