Living in China definitely warps ones internal calibers of what qualifies as quality (both in terms of product or service quality and envornmental conditions), though living on the periphery of China can be just as bad with the common fallacy of “China is polluted, here is not China; therefore, here is not polluted.”
I live and die by my apps which report the air quality index (AQI)–空气质量指数 (kong1qi4 zhi4liang4 zhi3shu4). The word is a fairly direct translation, with 空气 meaning air, 质量 meaning quality, and 指数 meaning index. “指数” is an easy word to remember because its individual characters mean “point [as in, to point with your finger] + number,” but my focus today is on quality.
“质量” can be broken down into 质 (zhi4), meaning the nature or character of something, and 量 (liang4), referring to the quantity or amount. Though 质量 is the highest frequency word containing 质, the characters base meaning is probably best exemplified by 素质 (su4zhi4) or 性质 (xing4zhi4), both of which mean quality in a more abstract sense, and are worthy of full discussions in their own rights.
The “opposite” of 质量, i.e. quantity as opposed to quality, is 数量 (shu4liang4, literally “number amount”). However, if we are speaking about research, e.g. qualitative and quantitative, the respective terms in Chinese are 定量 (ding4liang4) and 定性 (ding4xing4), where 量 and 性 are serving as shorthand for “number” and “nature” with 定 functioning as “to determine.”
Another interesting aspect of 质 and 质量 is the physics-specific meanings. 质 can mean “matter” or “substance,” though that is more clear when paired with 物 in 物质 (wu4zhi4, “matter; substance”), and 质 is the building block of all matter as a proton (质子，zhi4zi3 [Note: the zi3 is not a neutral tone]). In physics, 质量 means mass, which makes it much easier to distinguish between mass and weight (重量, “zhong4liang4,” literally “weight amount”) because mass is intrinsic to the substance while weight depends on gravitation.