LAPAN has measured rain acidity in Bandung, the location is Cipedes since 1985, with average pH in 1985 was 6.25. The pH condition 1985–1999 as follow: The monthly average of pH in period 1985–1992 was >5.6: in the middle of 1996–1997 it had big variation and than decrease until now. The monthly average of pH in 1997 until now was <5.6. The pH has decreasing trend, the reason was increasing fuel combustion for transportation and household because the area around the observation was change from rural to be transportation and settlement area.
The rain acidity comparison in Cipedes (rural site), Cicahuem (busy site), and Tanjungsari (remote site) hold in 1986–1987, the result was Tanjungsari the remote site had the lowest pH. It's suggested the reason was sulphur compound from Kamojang crater and air pollution from industrial area in south-east of Bandung were blown by the wind through this place.
The influence of air pollution to acid rain was studied by measurement NO3 − and SO4 2− in 5 places around Bandung, the results were: North of Bandung had the lowest NO3 − concentration because the traffics were low: but had the highest SO4 2− concentration; it's caused by emission of sulphur compounds from Tangkuban Perahu Montain. South of Bandung had the highest NO3 − concentration because the traffics were crowded and a lot of industries around it. In general Bandung had SO4 2− concentration higher than NO3 − concentration, it's suggested due to the influence of sulphur compound from Tangkuban Perahu Montain.
The observation rain acidity in Ciater at Tangkuban Perahu Montain started in 1996, the result in period 1996–1998 as follow: The pH had decreasing trend, it's due to the traffic near this observation increase, so the air pollution around this area increase, it will influence the rain acidity. The maximum monthly average of ph was 6.78 and minimum was 4.63, the pH monthly average generally < 6. In El NINO year 1997, the monthly average of pH in April and December were > 6.5.