The private health system in Australia operates on a "community rating" basis, whereby premiums do not vary solely because of a person's previous medical history, current state of health, or (generally speaking) their age (but see Lifetime Health Cover below). Balancing this are waiting periods, in particular for pre-existing conditions (usually referred to within the industry as PEA, which stands for "pre-existing ailment"). Funds are entitled to impose a waiting period of up to 12 months on benefits for any medical condition the signs and symptoms of which existed during the six months ending on the day the person first took out insurance. They are also entitled to impose a 12-month waiting period for benefits for treatment relating to an obstetric condition, and a 2-month waiting period for all other benefits when a person first takes out private insurance. Funds have the discretion to reduce or remove such waiting periods in individual cases. They are also free not to impose them to begin with, but this would place such a fund at risk of "adverse selection", attracting a disproportionate number of members from other funds, or from the pool of intending members who might otherwise have joined other funds. It would also attract people with existing medical conditions, who might not otherwise have taken out insurance at all because of the denial of benefits for 12 months due to the PEA Rule. The benefits paid out for these conditions would create pressure on premiums for all the fund's members, causing some to drop their membership, which would lead to further rises in premiums, and a vicious cycle of higher premiums-leaving members would ensue.
The environment is often cited as an important factor influencing the health status of individuals. This includes characteristics of the natural environment, the built environment and the social environment. Factors such as clean water and air, adequate housing, and safe communities and roads all have been found to contribute to good health, especially to the health of infants and children. Some studies have shown that a lack of neighborhood recreational spaces including natural environment leads to lower levels of personal satisfaction and higher levels of obesity, linked to lower overall health and well being. This suggests that the positive health benefits of natural space in urban neighborhoods should be taken into account in public policy and land use.