Data accessed from the BMC's yet to be released environment status report (ESR) for 2013-14 shows that pollutant levels in the air have gone up in a few areas, but the percentage of water samples found contaminated have reduced to11 this year from 20 last year.

Sulphur dioxide (SO2), nitrogen dioxide (NO2), suspended particulate matter (SPM) and ammonia (NH3) have seen an increase in all sites — Parel, Kalbadevi, Worli , Bandra and Sion — where the air-monitoring device was fitted. NO2 levels have shown an increase in all five areas, while SPM and SO2 increased in three and two areas respectively.

Experts say the levels of these gases have gone up due to increased construction activity and vehicular emissions.

SPM levels were all way above permissible limits prescribed by the pollution board, in fact in three places it was double that mark. The permissible level is 60μg/m3, whereas in Parel, which was the highest, it stood at 139μg/m3.

Similarly, NO2 levels in Sion and Bandra were higher than the permissible mark of 40μg/m3. The highest levels of NO2 were detected in Sion, which was 108 μg/m3.

However, the silver lining in the otherwise gloomy report is that water quality has improved considerably in a year. Last year, 41% of water samples from areas like Dongri and Sandhurst Road were found to be contaminated, the figure has been reduced to 24% this year.

Similarly bad areas like L ward (Kurla) and P-South (Goregaon) are showing an over 10% reduction in contaminated water supply parameters.

Civic officials say several steps have been taken by the BMC to ensure that water contamination complaints are reduced. Old pipelines have been replaced and large underground pipelines have been replaced by tunnels. The BMC has also activated its leak detection units in each ward to tackle complaints of leaks to reduce ingression of dirty water inside the line.

"The report gives a lot of data based on research and sampling. The BMC cleaned up its act after contamination complaints continued to increase, but authorities are not taking notice of air pollution levels and hence these are rising every year," said a civic official.

According to the report Mumbai's vehicular population is growing steadily. The city has 21.87 lakh vehicles as of March this year, as against 19.06 lakh vehicles last year.