That is, a measure of the actual exposure that people have to air pollutants during their daily routines, rather than measures of pollution at fixed locations. The inexpensive samplers offer scientists, environmentalists, engineers and others a simple but accurate way of measuring selected pollutants in air. The sampler, based on a Swedish design, is small and requires no electricity so is ideal for remote use. Nitrogen dioxide, sulfur dioxide, ammonia and other gases can be measured with the device. Acid rain Pure rainwater is slightly acidic, primarily because of dissolved carbon dioxide.
Air also contains naturally occurring organic acids and acidic particles.
The pH of unpolluted rainwater ranges from about 6 to just below 5. Fossil fuel combustion and industrial processes release into the air compounds containing oxides of sulfur and nitrogen. These compounds may then dissolve in cloud droplets, making rainwater more acidic. In other words, the pollutants can reach the ground in a wet or dry form. Both forms can harm soil, lakes, plants, buildings and people.