CHENNAI: A study on the city's health environment status has found that exposure levels to air and water pollutants were several times higher among residents in industrial/commercial zones compared to those in the rapidly diminishing exclusively residential spaces.

The `Comparative risk assessment of environmental health concerns for Chennai' conducted by the Sri Ramachandra Medical College in partnership with the Tamil Nadu Pollution Control Board also indicated that though health risks from air pollutants was substantial, a bigger health threat came from microbial contamination of water and improper solid waste disposal.

The study was designated across nine Indian cities by the Ministry of Environment and Forests to put together a national environmental health profile. In Chennai, it panned the population in North Chennai (industrial), T. Nagar (commercial) and Porur (residential) zones and ranked air pollution concerns against water and solid waste concerns in order to generate an environmental health profile for Chennai.

The results showed that risks for respiratory and gastrointestinal disorders consequent on exposure to air/water pollution were twice as high among the population in the industrial belt compared to those in residential areas (this sample served as the control group).

Another significant finding was that the risk of vector-borne diseases, including malaria, was four-fold higher in commercial zones and three-fold higher in the industrial belt vis-à-vis residential areas. Investigators also found that risk of eye irritation was an alarming 15-times higher in the industrial zone.

"The evidence suggests that there is a definite gradient in terms of health endpoints through industrial, commercial and residential zones," said Kalpana Balakrishnan, Head of Department of Environmental Health Engineering, SRMC, and lead investigator of the study.

Investigators are now compiling an environmental health database using GIS mapping which will extrapolate the cross-sectional data of the three zones for the entire city. The predictive software for risk assessment which will include parameters such as socio-economic class, type of housing, distance from road and vehicular density, is almost ready and the comprehensive ward-wise environmental health profile for the entire city is expected to be completed in six months.

"Once the comparative risk assessment is ready, planners can look at areas in terms of ranked risk and prioritise a set of interventions across the city," Dr. Kalpana Balakrishnan said.

"The database will serve as a policy guideline for future planning," a TNPCB official said.

The study, which followed the comparative health risk assessment (CRA) approach developed by the U.S. Environment Protection Agency, combined questionnaire-survey with sourcing of registries at 15 health posts across the three zones.

Primary health assessment was conducted on an estimated 3,000 members across 600 households selected through stratified random sampling from these zones while personal exposure assessment for particulates and blood lead measurements were performed on 10 per cent of members from the same households. Data on water quality and solid wastes were also collected from the same areas for comparison.

As part of the air quality assay, the daily averages data on criteria air pollutants from eight ambient air quality monitoring stations was sourced from the TNPCB for the period 2000-2003 in addition to the retrieval of outpatient data on cause of clinic visits from primary health centres of the three zones over the same period.

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