Middle East nations made up four of the 10 most air-polluted countries last year, an annual study has found. Behind only Chad, Iraq had the highest concentration of particulate matter (PM2.5) adjusted for population weighting, followed by Pakistan in third. <a href="https://www.thenationalnews.com/gulf-news/2022/03/22/oman-and-bahrain-among-nations-with-worst-air-quality-in-2021/" target="_blank">Bahrain</a> came fourth after being eighth in 2021. The 2022 World Air Quality Report, conducted by Swiss firm IQAir, studied levels of PM2.5 from 7,323 cities in 131 countries, regions and territories. PM2.5 are particles small enough to penetrate deep into the respiratory tract and<a href="https://www.thenationalnews.com/uae/2022/09/11/air-pollution-causes-lung-cancer-uk-scientists-find/" target="_blank"> lungs</a>, causing or exacerbating illnesses such as asthma and heart issues. A recent study involving<a href="https://www.thenationalnews.com/world/2023/02/02/chess-experiment-shows-performance-dips-in-polluted-air/" target="_blank"> chess players</a> found high levels can affect decision-making — and can even reach <a href="https://www.thenationalnews.com/health/2022/10/05/air-pollution-reaches-babies-in-the-womb/" target="_blank">babies</a> in the womb. Of the six major pollutants used to classify air quality, PM2.5 is considered the most harmful. The World Health Organisation recommends annual concentrations of PM2.5 should not exceed an average of 5 micrograms per cubic metre (µg/m³). Iraq's annual reading for last year was 80.1 µg/m3, and Bahrain's was 66.6 µg/m3. Kuwait's was 55.8 µg/m3, Egypt had 46.5 µg/m3 and the UAE 45.9. An estimated 4.2 million people die prematurely from air pollution every year, the WHO found. "Citizens in only 10 per cent of the global countries, regions and territories are breathing air that does not pose a risk to their health," the report released on Tuesday read. The findings are a good indication of global levels but not comprehensive — they cover only nations and areas with air-pollution sensors that measure PM2.5. Some nations that had previously appeared on the list provided insufficient data to be included this year, such as Oman and Afghanistan. Last year Oman was the sixth most PM2.5-polluted country. But others are accepting their responsibility to track air pollution in efforts to reduce it. Dubai has the most monitoring stations in the region, with almost a fifth of the total. Although car and industry pollution is a factor in air quality in the region, dust storms are a “major source” of natural pollution, the report said. Baghdad, the region’s most-polluted city, showed a nearly 75 per cent increase last year, going from 49.7 μg/m3 to 86.7 μg/m3.<a href="https://www.thenationalnews.com/mena/iraq/2022/05/05/iraq-sandstorm-more-than-1000-in-hospital-as-sky-turned-orange/" target="_blank"> Iraq</a> was hit by 10 sandstorms in only two months last year, with 5,000 people needing hospital treatment. The situation is forecast to deteriorate as water shortage drives more <a href="https://www.thenationalnews.com/mena/2022/05/19/nasa-to-launch-project-to-measure-dust-storms-from-space/" target="_blank">dust</a>. The county’s environment ministry has warned that over the next two decades Iraq could endure an average of 272 days of sandstorms a year, rising to more than 300 by 2050. The World Air Quality Report came only days after scientists at Australian Monash University released findings that almost nowhere on Earth was safe from air pollution in 2019. Tuesday's report supports this finding. Only 13 of the 131 countries included had average levels of PM2.5 at or below the WHO's safe annual recommendation of 5 µg/m3.