Jakarta (ANTARA) - Rain often brings changes to the atmospheric\natmosphere. After heavy rain, the air usually feels cooler and fresher.\nSkies that previously appeared hazy or dusty may also appear\nclearer.<\/p>\n
This condition is not merely a sensation. Rain can indeed help reduce\nsome pollutants in the air, particularly small particles such as PM2.5.\nHowever, this does not mean that every time it rains, the air\nautomatically becomes clean.<\/p>\n
One way rain helps clean the air is through a process known as wet\nscavenging, or the removal of pollutants by precipitation. As raindrops\nfall through the atmosphere, some particles floating in the air can\nadhere to or be carried by these droplets. The particles then fall to\nthe ground along with the rainwater.<\/p>\n
This process primarily affects particulate matter (PM), including the\nextremely small PM2.5. A study observing the relationship between\nrainfall and PM2.5 found that average PM2.5 concentrations dropped by\napproximately 20.99 per cent one hour after rain began compared to the\nhour before. The research also found that the reduction effect was more\nnoticeable as rainfall intensity increased.<\/p>\n
Nevertheless, there are limits. Rain does not eliminate all types of\npollutants from the atmosphere. Some pollutants are in gaseous form,\nsuch as nitrogen dioxide (NO2), sulphur dioxide (SO2), and carbon\nmonoxide (CO), which behave differently in the atmosphere.<\/p>\n
Furthermore, air quality is not solely determined by whether it rains\nor not. Emission sources such as motor vehicles, industry, fuel\ncombustion, waste burning, and even forest fires can continue to produce\npollutants after the rain has stopped.<\/p>\n
The WHO notes that particulates, including PM2.5, are among the\nprimary components of air pollution that impact health. Exposure to air\npollution is also linked to cardiovascular and respiratory diseases.<\/p>\n
Why does the air feel fresher after rain? Several factors can make\nthe air feel more comfortable after rainfall. In addition to some\nparticulates being carried away by rainwater, atmospheric conditions\nduring rain can also help reduce pollutant concentrations near the\nsurface. Rain is usually accompanied by changes in wind, temperature,\nand humidity. If there is sufficient air movement, pollutants can be\ndispersed, lowering their concentration in a single location.<\/p>\n
Interestingly, the relationship between rain and pollution is not as\nsimple as \u201crain falls, pollution drops.\u201d Research published in the\njournal Atmospheric Environment in 202 moving towards 2025 found that\nlight rain under certain conditions can actually increase aerosol\nconcentrations. In that study, rain acts as a cleanser when pollution\nlevels are high, but can have a different effect when the atmosphere is\nalready very clean. This means that rainfall intensity, particle size,\natmospheric conditions, and pre-rain pollution levels all influence the\nfinal outcome. This is why air quality cannot be assessed solely based\non the presence or absence of rain.<\/p>\n
Is it safe to be active outdoors after rain? It is not always\nnecessary to wait for rain to ensure the air is safe, but it is also\ninaccurate to view rain as a \u201cperfect natural air cleanser.\u201d The most\npractical method is to check the air quality index or information in\nyour respective area. If PM2.5 concentrations remain high after rain,\nespecially in areas with large emission sources, the public still needs\nto be mindful of outdoor activities.<\/p>\n
The WHO establishes air quality guidelines based on various\npollutants because exposure to particulates and other pollutants still\nposes health risks even as concentrations fluctuate.<\/p>\n
In conclusion, while rain can help lower levels of certain air\npollutants, particularly particulates that can be carried by water\ndroplets, the effect is temporary and does not apply equally to all\ntypes of pollutants or all weather conditions. In other words, rain can\nhelp \u201cwash\u201d some pollution from the air, but it does not mean the air is\nguaranteed to be pollution-free after it rains.<\/p>", "url": "https:\/\/jawawa.id\/newsitem\/can-rain-help-reduce-air-pollution-levels-1790557405", "image": "" }, "sponsor": "Okusi Associates", "sponsor_url": "https:\/\/okusiassociates.com" }