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Is pollen worse this year? Why we may see higher pollen counts in the years to come

Spring has begun and, in the South, it has been marked with a yellow dust covering everything in sight. Across most of the Southern United States, pollen has taken over everything from cars and roads to rooftops and sidewalks. A yellow haze has become the norm in Memphis, one of the worst cities for allergies due to pollen counts. According to IQAir, an air quality monitoring organization, pollen counts vary widely in Memphis due to environmental conditions, such as temperature, humidity, wind speed, and sunlight. Here's what to know about the extra pollen. An unforeseen side effect of climate change is increased pollen counts. Recent climate change has caused weather patterns to shift. There are more days without frost or freezes, warmer seasonal air temperatures and more carbon dioxide in the atmosphere, all of which can contribute to higher pollen counts and earlier pollen seasons. Warmer temperatures and more carbon dioxide allow plants to grow more aggressively, which can account for more pollen in the air. Allergy season will likely continue to worsen for many individuals with tree, grass or weed allergies. According to the Proceedings of the National Academy of Sciences of the United States of America, pollen amounts between 1990 and 2018 increased by up to 21%. Memphis stayed in the medium to high range for pollen levels in March. The scale for pollen goes from 0 to 12 and is divided into four categories, according to Low: 0-2.4 Low-medium: 2.5-4.8 Medium: 4.9-7.2 Medium-high: 7.3-9.6 High: 9.7-12 In Memphis, there were six days in March when the pollen levels were 9.7 or higher. For March, nine days were in the medium-high category, and four were in the medium category. For the coming week, Memphis is expected to have a break in pollen counts with low counts forecasted for the next few days. There are three parts to pollen season: tree, grass and weed. In total, the three seasons cover about nine months: February through October. Tree pollen allergy season begins in late February and lasts through April. Due to milder temperatures, some areas in the South can see pollen production as early as December or January. Trees that cause the most allergy symptoms are: Alder Ash Aspen Beech Birch Box elder Cedar Cottonwood Elm Hickory Juniper Maple Mulberry Oak Olive Pecan Poplar Walnut Willow Grass pollen allergy season lasts from April through early June. Like trees, the South is known to see grass pollen production throughout the year in warmer areas. Grasses that cause allergy symptoms are: Bahia Bermuda Fescue Johnson Kentucky blue Orchard Rye Sweet vernal Timothy Weed pollen season is the last to begin of the three and lasts from late summer through fall. Ragweed is the most common weed to cause allergy symptoms in the United States. Weeds that cause symptoms include: Burning bush Cocklebur Lamb's-quarters Mugwort Pigweed Ragweed Russian thistle Sagebrush Tumbleweed This article originally appeared on Memphis Commercial Appeal: Why is pollen season so bad this year? How long does season last?