( CNN ) -- Beijing residents blanketed by smog are pointing to U.S. readings on pollution levels -- and slamming official reports from the Chinese government . On Weibo , the Chinese version of Twitter , more and more people are uploading and reposting screen captures from air-quality-monitoring apps -- generally one from the U.S. Embassy -- highlighting `` very unhealthy '' or `` hazardous '' pollution levels , at times that China officially reported only `` slight pollution '' in the same areas . China acknowledges the concerns and notes that it uses a different system to measure air pollution . State-run news agency Global Times on Tuesday carried the headline , `` Non-government air quality assessments on the rise due to distrust over official data . '' `` Zeal for independent assessments of air quality has been on the rise nationwide in China recently , amid public distrust over official data resulting from the failure of national evaluations to include PM 2.5 level , an air pollution index used worldwide , in their calculations , '' the article states . The U.S. Embassy explains that PM 2.5 refers to fine particulates less than 2.5 micrometers in diameter . The U.S. Consulate General in Guangzhou , China , explains that these smaller particles `` are believed to pose the largest health risks '' and `` are small enough to get into the lungs and even the blood stream . '' Chinese monitoring stations around Beijing track only larger , `` coarse '' particulates , between 2.5 and 10 micrometers in diameter . On Monday , the Beijing Municipal Environmental Protection Bureau stated that the Air Pollution Index ( API ) was between 150 to 170 , indicating `` slight '' pollution . The U.S. monitor , meanwhile , which sends out tweets throughout the day , reported at times on Monday that the air in Beijing was `` hazardous , '' with Air Quality Index ( AQI ) readings over 300 . On October 9 , the U.S. monitor reported a reading of over 500 , which it labeled `` beyond index . '' The official government reading for that same date states there was `` slight pollution . '' While many official reports on Chinese state-run media refer to the air as being filled with `` fog , '' the government acknowledges the haze is due to smog . The state-run China Daily reported this week that while `` fog alerts '' are declared , `` Ma Jun , director of the Institute of Public and Environment Affairs , said the hazes that have been smothering Beijing are really 'smog . ' '' While pollution is an ongoing concern in the country , the weather in recent days has made matters worse , said CNN International weather anchor Mari Ramos . `` Beijing 's weather has been dominated by high pressure , which means sinking air and dry days . This weather pattern aggravates their air quality problem , '' Ramos said . `` The air is stagnant , there is no mixing and all the pollutants are trapped near the surface . '' The Chinese capital has only had 1.5 mm of rain since October 14 , she said . `` There is a glimmer of hope on the horizon , but not until the end of the week . By Friday , when a cold front comes through , there is a small chance of rain , '' Ramos said , adding that even if it does n't rain , the end to the current weather pattern will bring a `` welcome relief . '' In posts online , many Chinese people say they can smell sulfur dioxide in the air . Some have posted photos of sites throughout Beijing , showing how little visibility there is . The poor air quality has caused a surge in the numbers of patients with respiratory problems , and the Beijing Meteorological Bureau issued four yellow alerts for dense fog in the last two days , the Global Times article says . Doctors suggest people of all ages avoid outdoor activities . CNN 's Tian Shao and Jaime FlorCruz in Beijing contributed to this report .
U.S. readings show ` ` hazardous '' air while Canada reports ` ` slight . '' China 's readings do not include fine air . China 's state - run media expresses distrust over official smog data . China 's weather has compounded the problem in recent days .