LINDA Xu and her fiance are having fun decorating their new apartment in Zhabei District - but it's not just about looking nice, it's about ensuring their family's health.

They are choosing non-toxic and low-toxicity materials. They plan to get a safety/toxicity check of the air and let the decorated apartment stand vacant and "air out" for several months before they move in.

Warnings in the media about hazardous materials used in home construction and decoration scared the couple.

"It's horrifying. I don't want my baby to get leukemia because I didn't take the time to choose safe materials for interior decoration," says Xu.

Since most apartments are sold unfinished, they have to select flooring (including tiles, carpeting), paneling, cupboards, counters, paint, wall covering, fabrics, draperies, blinds, furniture and appliances and fixtures.

They are keenly aware that many materials used in construction, furnishing and remodeling can be toxic, so they are choosing carefully, asking questions, reading labels and generally choosing big outlets and big brands that are supposed to meet high national safety standards.

The list of common and dangerous elements is long: radon gas, volatile organic compounds like formaldehyde, benzene, polyvinyal chloride, ammonia and many other chemicals. Toxins in materials are released into the air and accumulate over time.

Experts advise letting an apartment stand empty and "air" for at least three months. Airing in summer is best because high temperatures accelerate the release of volatile substances.

Xu is choosing natural materials and fibers instead of synthetics wherever possible and checking that adhesives used do not contain high levels of harmful chemicals like formaldehyde and paints do not contain mercury or lead.

"It is tiring to shop around since we don't know much about interior decoration but it's worthwhile," says Xu. "Only in this can we be sure about what is used in our apartment."

"Hazardous finishing materials have become a major threat to people's health, especially vulnerable children," according to Dr Yan Chonghuai, director of the Environmental Medicine Laboratory of Shanghai Institute of Pediatrics.

New research from the World Health Organization indicates that radon (colorless, odorless, tasteless radioactive gas), which exists in many building and decoration materials, has now become the second biggest cause of lung cancer (smoking is the first).

Radon is emitted when radium in building materials naturally breaks down. It may be present in tiles, stone, granite, gypsum (common in wallboard/sheetrock/drywall), concrete, cement and other materials. Not all materials are dangerous and not all emit high levels of radon.

World Health Organization research indicates that 3 to 14 percent of lung cancer cases worldwide are caused by inhaling radon gas. The research was released late last month in China in a media forum, "Promoting Popular Science of Cancer Prevention and Treatment in China."

Radon particles can be inhaled, release radiation in the body and thus cause cancer, according to Dr Yan.

High and prolonged exposure to radon usually means a high risk of lung cancer, according to the WHO report.

Apart from radon, there are other dangerous compounds commonly found in decorating materials, such as formaldehyde, benzene, chlorine and ammonia, among others.

These elements exist in some paints (these days most new paints are "green") and wood materials, such as pressed wood composition panels. Finishing and sealing materials like varnish are volatile.

Long exposure may cause runny eyes, vomiting, fatigue, irregular menstruation, even cancer and leukemia, says Dr Yan.

Formaldehyde (low levels are common, high levels can be smelled) is confirmed as carcinogenic and teratogenic (causing malformation of the fetus or embryo) substance by WHO.

Carey Li, a 27-year-old woman, decided to have an abortion last year when she found out that her seven-month-old fetus had underdeveloped kidneys in ultrasonic check. She suspects her newly constructed and decorated office space was the cause, noting that a female colleague in the same office had the same experience. Her aborted fetus had malformations in the thorax.

An increasing number of childhood leukemia cases has focused medical attention on pollution from interior decoeration.

"Though there is no verdict so far identifying interior decoration as the major cause of higher leukemia rates, research on child patients did find relatively high formaldehyde concentrations in their apartments," says Dr Yan.

The statistics only show the formaldehyde level after a person falls ill - it's even higher when an apartment is freshly decorated using toxic materials, says Dr Yan.

As solid wood is both rare and expensive, many families choose wood-like composition board for flooring. paneling and furnishings. These materials use wood chips and are stuck together with adhesive using high concentrations of formaldehyde, according to Kevin Rong, sales manager of a major supermarket chain selling home decorating materials.

Most big building material companies have reduced harmful elements in their products, such as paint, flooring and adhesives.

Proper sealing of the composition board can largely reduce harmful elements released into the air, says Rong.

But combination board made by small private factories or decoration companies may not meet the standard.

As for widely used materials that may have radioactive elements (such as stone and tiles), it is widely acknowledged that it's best not to cover large areas and to vary the materials used.

Dr Yan says big brands and big markets are relatively safe and notes that solid wood is always best.

"Most volatile substance will be dispersed with sufficient airing," he says. "The longer the airing, the safer your apartment will be," says Dr Yan.

Warm temperatures accelerate the release of dangerous volatile substances, so it's best to finish the interior decoratioon work in spring, let it air through hot summer, and move in during autum when it's cooler. Decorating tips

1. Choose natural materials wherever possible.

2. Use materials that meet national health standards.

3. Do not use too much rock and earthen materials such as marble, granite and ceramic tile - they may produce radon.

4. Air the apartment for at least two or three months before moving in.

5. Get an inspection of indoor air quality as some harmful substances have no odor.

6. Keep green plants to help purify the air. Aloe and spider plants help absorb formaldehyde. Ivy, cycas (sago palm) absorb benzene. Lily helps remove carbon dioxide and sulfur dioxide. Calyx canthus helps remove mercury vapor.