Bihar's Begusarai ranked as world's most polluted city: Report

According to the World Air Quality Report by IQAir, nine out of the top 10 most polluted cities of 2023 were located in India. Begusarai in Bihar ranked as the worst, with an average PM2.5 level of 118.9 micrograms per cubic meter. Guwahati followed closely behind with a PM2.5 level of 105.4. Lahore, Pakistan, was the only city outside of India to make it into the top 10 list. IQAir collects air-sensor data globally to compile its report.

As per the report, Delhi ranked as the most polluted capital city globally in 2023, with an average PM2.5 level of 77.4. India also emerged as the third most polluted country out of 134 nations. This marks a decline from the previous year when India ranked eighth in terms of pollution, with an average PM2.5 level of 53.3. Overall, air quality in India worsened in 2023 compared to the preceding year.

Bangladesh was labeled as the most polluted country, with Pakistan coming in second, according to the report. PM2.5, a prevalent form of air pollution, is known to cause more fatalities than any other pollutant, as stated by Glory Dolphin Hammes, CEO of IQAir's North American division, which has been issuing annual World Air Quality reports since 2017.

“When you’re trying to identify high levels that may be located in pockets of the city, that won’t be captured by a network that’s not dense enough, or just a couple monitors quite outside the city,” Daouda said.

Even at relatively low levels, the impacts of this type of pollution are severe. In 2021, the WHO tightened its recommended guidelines for PM2.5 pollution from an average of 10 micrograms per cubic meter to 5 micrograms per cubic meter. However, according to IQAir, very few countries meet this threshold.

The report revealed that last year, only 10 countries and 9 percent of global cities had air quality that complied with WHO guidelines for PM2.5 pollution. Regions most affected included the Middle East, Africa, and Central and South Asia.

PM stands for particulate matter, and 2.5 denotes its size, which is 2.5 microns, or 1/30th the diameter of a single strand of hair. The tiny size of PM2.5 particles is what makes them extremely dangerous.

PM2.5 pollution is linked to higher rates of heart attack and stroke and can lead to oxidative stress, which damages the body's cells faster than they can repair. This stress is associated with various illnesses, including Parkinson's disease and cancer. Recent studies also indicate that exposure to PM2.5 can impact brain development, especially concerning for young children.