Although these chemicals have been detected in outdoor air, both in Sydney and Melbourne, the levels are too low to cause many cases of lung cancer. One of the most alarming things during the London fog in 1952 was that prize animals at the Smithfield Show developed respiratory distress and died. A considerable number of laboratory experiments since then have confirmed that certain animals are particularly susceptible to air pollution. This work has also taught us how pollutants damage the lung. Some of the guidelines to control pollution have been based upon the effect on vegetation.
Ozone damages forests and reduces crop yields.
It is also possible that some trees and grasses produce more irritating pollens when stressed by pollution. The Environment Protection Authorities in most States can predict when high levels of pollution will occur, and announce smog alerts. A summary of air pollution levels is sometimes presented in the news. Patients with asthma or other chronic lung diseases should notice whether they have more symptoms, worse lung function, or need more reliever medication on these days. If this does occur, they should stay indoors if possible.