English: The skies over eastern Pakistan and northwestern India were choked with a dense gray haze for most of November 2023. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite acquired a true-color image of the heavy aerosols haze on November 9. The layer of aerosols was so thick that it obscured much of the land from view.

Several media sources, including the Associated Press, reported that by November 9 the region had been clouded by gray smog for at least four consecutive days. This was confirmed by a review of Terra MODIS satellite images. In fact, satellite imagery showed the most dense aerosol cloud over the region occurred on November 8. Some clearing had occurred by November 11.

Air quality indexes in New Delhi, India, showed PM 2.5 reached 285 on November 9. This is “very unhealthy”. This is the second-most severe air quality level. PM2.5 are aerosols (small particles suspended in air) which measure about one-thirtieth the width of a human hair and are particularly dangerous as they can be inhaled deep into the lungs. On that same day, Lahore, Pakistan reported PM2.5 of over 450, which is in the “Hazardous” (most severe) range. On November 9, the Associated Press reported, “Toxic gray smog has sickened tens of thousands of people in Pakistan’s cultural capital of Lahore, forcing authorities to shut schools, markets and parks for four days”.

Not only does aerosol pollution create a short-term health hazard, but it also has long-lasting effects on human health. A report released in September 2023 by the Air Quality Life Index states that particulate air pollution remains the world’s greatest threat to human life expectancy. Their summary states that, “The Air Quality Index Annual Update 2023 found that if fine particulate pollution (PM2.5) was reduced to meet the World Health Organization’s (WHO) guidelines, the average person would add 2.3 years onto their life expectancy, a combined 17.8 billion life-years saved worldwide. The report also found that particulate pollution remains the world’s greatest external risk to human health, with the impact on life expectancy comparable to smoking, three times that of alcohol and unsafe water and five times that of transport injuries.”