New Delhi: IF LILLEE doesn’t get you, Thommo will remember the Australian cricketing chant of the 1970s? There’s a morbid remix, which sounds apt for contemporary Delhi: If lead won’t get you, benzene will.

When the government got rid of the lead content in petrol in February 2000, it thought Delhi would finally have cleaner, healthier air. Lead pollution is extremely harmful, known to cause breathing disorders, and even cancer.

The tradeoff in eliminating lead was increase in the benzene content. This was required to maintain a certain chemical balance. The bad news, trickling in two years later, is that benzene, too, has been found to be malevolent. The only concession is that it may take longer to kill. Long-term exposure to benzene is now known to cause leukemia, or blood cancer.

A paper presented at a workshop organised by the Central Pollution Control Board (CPCB) last week defines benzene as a "colourless, cancer-causing liquid with a pleasant odour". An issue seriously discussed was the monitoring of benzene levels in vehicular exhaust in the Capital.

The CPCB and Lok Nayak Jai Prakash Narain Hospital /have jointly initiated a study into the repercussions of benzene in-halation on the health of a physically fit individual. The study will be conducted under the supervision of Dr TK Joshi of LNJPN Hospital.

The findings of the study are expected to establish whether lead in fuel has been replaced by another polluting agent. The study may also recommend the optimum levels of benzene in petrol.

A recent edition of the Journal of the American Medical Association has worried environmentalists in Delhi. An article in the journal establishes a direct correlation between air pollution and lung cancer.

Studies on which this article is based reveal that an inhabitant of a "heavily polluted metropolitan area" is 12 per cent more likely than someone living in clean, healthy environs to acquire lung cancer. This is being widely regarded in the US as the "best epidemiological evidence" connecting air pollution to lung cancer.

Environmentalists and doctors in New Delhi feel that there are lessons to be learnt from the American studies. Research material here is limited because no study has been done linking pollution to any one disease like cancer.

But experts are of the view that thefe’s no evidence to suggest that the situation in the Capital is critical, or that the air which Delhi breathes is lethal.

The Additional Director of CPCB, Dr S.D. Makhijani, points out that the US study talks about emissions from coal-powered power plants and factories and diesel vehicles.

In Delhi, the three main thermal power plants use electrostatic precipitators. "The emission is controlled. There might be a bit of particulate matter and oxides of sulphur that are released into the air. But the problem of pollution from thermal power emission is not acute," Makhijani maintains.

Industrial emissions too are not alarming, Makhijani claims. Delhi does not have any big industry Whatever big industries that were there in Delhi earlier have been closed down now Of course there are about a lakh of small industries. The emission levels of these industries, however, is not that much of a problem."

It is the vehicular pollution, both diesel and well petrol-induced, which continues to be the major headache for the Capital, which has the highest number of automobiles in the country higher than all other metros put together.

While the number of diesel vehicles add up to only 10 per cent of the total vehicular population in the Capital, their contribution to vehicular pollution is a disproportionate 25 per cent. "The number of diesel vehicles have reduced after the introduction of Compressed Natural Gas (CNG). But still, the phase-out is getting delayed because of repeated extension of deadlines," Makhtani adds. Air pollution continues.

Although diesel-related pollution remains a problem, post-CNG, the focus the real worry is the benzene content in lead-free petrol.

The paper presented on benzene at the CPCB workshop mentions the likely impact of the chemical on petrol-pump workers. The study supervised by Dr Joshi will also examine the ex-tent to which the health of the population in congested areas is compromised by inhalation of automobile emissions.

"Although acceptable levels of benzene in petrol are yet to be spelt out, benzene content in the air is being monitored at nine points in the Capital; at six places manually and at the remaining three through automatic monitoring," informs Makhijani.

The six places where manual monitoring is being done are Nizamuddin, Siri Fort, Janakpuri, Shahzada Bagh Ashok Vihar and Shahdara. At Zakira, ITO and again at Siri Fort, monitoring is being done with automatic machines. While the monitoring and data collection are being done by CPCB, Dr Joshi of LNJPN Hospital will look into the health aspect.

This will provide the date for subsequent research to under-stand how exposure to benzene causes cancer.

The study will be conducted among two sub-groups of the population the occupationally exposed category (like petrol pump workers) and a community sub-group.

Besides the study on benzene there’s another project on the contribution of air pollution to respiratory diseases. It was jointly initiated three years ago by CPCB along with the A1l India Institute of Medical Sciences (AIIMS).

For the study, air quality was monitored at a few places in the Capital to find out the contents of oxides of sulphur and nitrogen, suspended particulate matter and very importantly inhalable suspended particulate matter, also known as PM10.

"PM10 is carcinogenic (cancer causing) Owing to their very small size, these particles can easily be inhaled into the respiratory systems" explains Makhijani. It is already established that continuous exposure to PM10 can lead to conditions of asthma and bronchitis.

Interestingly, the US study-conducted in New York, Los Angeles, Chicago and Washington - prominently refers to "fine particle emissions", another term for PM10. Earlier US re search had linked it to "heart attacks, strokes and asthma. The new study establishes its link-age with lung cancer deaths in the US.

This strikes an ominous resonance in Delhi. However only local studies such as the ones being conducted will eventually clear the air. The big question is whether we can take the air we breathe for granted.