New Delhi: Air toxin levels in Delhi rose sharply on Thursday with the Air Quality Index (AQI) crossing the 'critical' level, from 219 on Wednesday to 410 on Thursday. This happened because the cloud cover trapped air pollutants preventing them from dispersing and mixing.

Other than fine particle pollution (PM2.5) measured by AQI, ozone (O3) gas levels were very high in the national capital, almost two times the safe level of 50 parts per billion.

PM2.5 are fine particles that can penetrate inside an individual's lungs. On the other hand, exposure to ozone gas can cause respiratory distress and can worsen lung diseases like chronic bronchitis and asthma. Depending on the level of exposure, it can lead to permanent lung damage in individuals, inflaming their airways.

Spike in ozone levels was directly linked with the soaring temperatures in Delhi. Its levels will remain high till the time rainfall starts in the capital, according to experts. UV levels were also very high.

An expert said "The temperature in Pusa is also about three to four degrees lower which may have brought down O3 levels. O3 levels go up in the urban heat islands where concrete spaces, vehicular and air conditioner exhausts cause temperatures to rise".

According to the scientists, the dust storm that hit the capital in the early morning hours on Thursday led to a sharp increase in PM 2.5 as well as PM10 (coarse pollution particles) levels.

Gufran Beig, project director of System of Air Quality Weather Forecasting and Research (SAFAR) added "Ozone is created in conditions of high temperature and direct sunlight, accompanied with high levels of oxides of nitrogen (NOx), carbon monoxide (CO) and other volatile organic compounds (VOCs). They peaked this week probably because temperatures were extremely high".

According to the experts, the residents must include green leafy vegetables and fruits and drink more fluids, which will help them in fighting air pollutants.

SAFAR in collaboration with the Indian Meteorological Department (IMD) launched the Ultraviolet (UV) index for the national capital which revealed that the UV index for Delhi was 7.2 whereas the safe level is 1 to 4.