Delhi's air quality for the first time recorded a "moderate" level today after remaining in the "severe" category for nearly a week, according to monitoring agencies. The presence of moisture in the air is the main reason for the improvement in the air quality, the System of Air Quality and Weather Forecasting and Research Institute (SAFAR) of the central government said. The weather office has forecast the possibility of rain and thunderstorm in the national capital. The pollution level had spiked to an alarming "severe" category on Tuesday due to dust storms in western India, particularly Rajasthan, which increased coarser particles in the air. According to the data by the Central Pollution Control Board (CPCB), the PM10 level (presence of particles with diameter less than 10 mm) was recorded at 191 in Delhi-NCR and 187 in Delhi today. The PM10 level between 0-100 is considered \u201cgood\u201d, 101-250 \u201cmoderate \u201d, 251-350 \u201cpoor\u201d, 351-430 "very poor" and 431-550 \u201csevere\u201d. The PM2.5 level (presence of particles with diameter less than 2.5 mm) that deteriorated from "very poor" to "severe", has now come down to "moderate" category. It was 68 in Delhi-NCR and 66 in Delhi today, the CPCB data said. Even Anand Vihar, which generally has a very high level of pollution, registered a PM10 grade of 269 and PM 2.5 level of 100, which falls in the 'poor' category. "The air quality might come down to even satisfactory level due to rain and thunderstorm," Gufran Beig, a scientist at the SAFAR, said. The sudden rise in the air pollution level has brought to light that severe pollution could be a 'summer-time problem' too, according to scientists.