1 Substance abuse. Abuse of drugs and alcohol can contribute to panic disorder.  Major life stress. Stressful events and major life transitions, such as the death of a loved one, can sometimes trigger panic attacks, which can potentially recur and go on to become panic disorder.
Zero emission refers to an engine, motor, process, or other energy source, that emits no waste products that pollutes the environment or disrupts the climate. Contents.
Natural gas is touted for its potential to reduce emissions by edging out, for example, coal as an electricity source and diesel as truck fuel. But the appeal of a cleaner, abundant fossil fuel source cuts both ways.