Oxygen levels below 1% are very effective in delaying rancidity, staleness, and other deterioration symptoms of pistachios and other tree nuts. Packaging using vacuum or nitrogen flushing to reach such oxygen concentration is recommended to maintain quality of all tree nuts, including pistachio. Remember that maintaining optimal ranges of temperatures (0-10C) and relative humidity (55-65%) is far more important in preserving nut quality than modified atmospheres. --Adel A. Kader