Every breath you take...

The equivalent of the population of a small town dies annually in Delhi from causes linked to air pollution; in Delhi in 2019, says the State of Global Air (SoGA) 2022 report (bit.ly/3WPVy8N), 29,900 people died. Leading up to winter, Delhi's air quality worsens due to pollutants from neighbouring farmlands where crop stubble is set ablaze, but the city is highly polluted round the year. SoGA 2022 notes that among the world's most populous cities, Delhi is the most polluted, followed by Kolkata, with Mumbai at 15th place. The Delhiite breathes almost two times the amount of PM_2.5 pollutants threshold mentioned in the Indian standard, which itself is 12 times as much as specified in the guidelines of the World Health Organization (WHO).

Airborne particles are measured at 0.3 microns or smaller diameter, 2.5 microns or smaller, and 10 microns or smaller. These particles travel deep inside the lungs, and some can breach the blood brain barrier. Gases also contribute to air pollution: nitrogen dioxide, ozone, carbon monoxide, sulphur dioxide. According to WHO, air pollution causes heart disease, stroke, chronic obstructive pulmonary disease, lung cancer and acute respiratory infections. Parkinson's disease, stroke or neurodevelopmental disorders are also likelier, according to other research. 

WHO records that air pollution kills 42 lakh people around the world each year. The Guardian, quoting WHO in 2014, noted that air pollution is "the world's single biggest environmental health risk". 

That's why, in recent years, research is empowering private individuals to protect themselves as far as possible from air pollution and its effects. A round-up of what a few research papers advise: