The digital debate, chasing paper and swimming green.

What are some tips on maintaining a "green" swimming pool?--Jim Humphey, North Andover, MA

Evidence on the dangers of chlorine continues to mount, as a recent study shows a possible link of child asthma cases to exposure of chlorine byproducts used in indoor pools, says the Water Quality and Health Council. However, a chemically dependent, water-hogging swimming pool can easily be turned into something more Earth-friendly. Even this summer's Olympic games in Athens are catching on to greener alternatives by heating their pools with solar collectors.

Other methods include reducing the need for toxics ill the nearly eight million pools across the U.S. According to the National Sanitation Foundation, using substitutes such as ozone and UV fight to disinfect your pool can reduce the need for chemicals. The Chlorine-Free Products "Association recently endorsed a corn party developing an ozone-only public pool, which operates without the need of any harmful additives.

Water conservation is also an important step in this greening process. The National Pool and Spa Institute (NPSI) says installing a safety cover can reduce evaporation by 90 percent.

NPSI also suggests purchasing water-saving equipment, reducing the amount of pool water to prevent wasteful splashing, and maintaining your pool often to reduce excess cleaning and backrwashing. Backwashed water may also be used for irrigation purposes, but Jeanette Smith, manager of standards at NPSI, advises checking with local health departments for any disposal restrictions. CONTACT: Chlorine-Free Products Association, [phone], www.chlorinefreeproducts.org; National Pool and Spa Institute, [phone], www.nspi.org/news_room/news_releases/316.cfm; National Sanitation Foundation, (800)NSF-MARK, www.nsf.org; National Water Quality and Health Council, www.waterandhealth.org/news_center/in_news 060603.html.--Fred Durso, Jr.

What are the environmental benefits of digital versus film photography?--Bob Kline, Lancaster, PA

Film developing uses an array of extremely toxic, strictly regulated chemicals. The book Toxics A to Z: A Guide to Everyday Pollution Hazards describes how one film chemical, hydroquinone, has been known to cause eye and skin irritation.

The Environmental Protection Agency says that leftover processing solutions can contain high amounts of heavy metals like silver that were once part of the film paper. While silver recovery systems remove most of the chemical, other dangerous solvents are used to clean film-developing machinery.

Kodak claims that 90 percent of photographic effluent is water, while the remaining chemicals (except silver).are broken down by light and microorganisms in the soil.

Improvements have been made to dramatically reduce the environmental impact of digital photography, says Jim Blamphin, spokesperson for the Eastman Kodak Company. Heavy metals have been eliminated in camera production, the amount of batteries needed has been reduced and camera mass has been decreased by 50 percent. Blamphin notes that recent software developments enable the downloading of 1,000 images in less than 11 minutes, thus saving on energy usage. CONTACT: The Eastman Kodak Company, [phone], www.kodak.com; EPA, [phone], www.epa.gov/fedsite/medical/pho to.html.--Fred Durso, Jr.

How can I save paper in my office environment?--Wee Kheong, Singapore

The U.S. uses approximately four million tons of copy paper annually, with the average office worker using 10,000 sheets a year, according to the Lawrence National Berkeley Laboratory (LBL). The environmental effects of papermaking weigh heavily on our air and water quality, and on our forests.

Recycling and buying recycled paper is important, but Bruce Nordam, a researcher at LBL, says more attention also needs to be given to reducing paper usage. Resetting your copier and printer functions to save paper is an excellent way to reduce usage. By using the "duplexing" feature, for instance, you can print on both sides of the page. The "reduction" feature allows more than one page to be printed on each sheet. Posting signs on these machines and enforcing a paper conservation policy is an effective way to reap both environmental and economic benefits.

Software such as Webprint Plus ($39.95) gives the user total control over the printing process, thus limiting the amount of toner and paper needed. The software saves you from printing useless images and unwanted text. CONTACT: Care2, [phone], www.care2.com/channels/solutions/ home/202; Lawrence Berkeley National. Laboratory, http:// eetd.lbl.gov; MacEase, www.macease.com. --Fred Durso, Jr.

Send your questions about environmental issues, from the personal to the political, to Ask E, P.O. Box 5098, Westport, CT 06881, or e-mail [e-mail]. Please keep your questions brief. Include your full name, address and a daytime phone number.