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世界卫生组织制定空气污染的新准则１９９１年世界卫生组织（ＷＨＯ）成立专家工作组以更新它的１９８７年的准则。新准则建议将目前建议的空气中二氧化氮允许极限降低一半，从２１０／１０亿降至１１０／１０亿。对空气中颗粒污染没有安全水平。空气中颗粒一词是指直径在...
WHO set new guidelines for air pollution In 1991, the World Health Organization (WHO) set up an expert working group to update its 1987 guidelines. The new guidelines suggest reducing the current allowable limit for nitrogen dioxide in air by half from 210/10 billion to 110/10 billion. There is no safe level of particulate contamination in the air. The word particle in air refers to the diameter in ...