• What is the AQI?

  • The Air Quality Index (AQI) is the EPA's system for reporting air quality, focusing on five major pollutants: ground-level ozone, particle pollution (PM2.5 and PM10), carbon monoxide, sulfur dioxide, and nitrogen dioxide.
  • The scale ranges from 0 to 500, with higher numbers indicating worse air quality.
  • It is divided into six color-coded categories (Green, Yellow, Orange, Red, Purple, Maroon) to help the public quickly understand health risks.

• Evolving Standards

  • The EPA is required by the Clean Air Act to review national air quality standards every five years.
  • Standards have become more stringent over time; for instance, what was considered "good" air quality 10-25 years ago might not meet today's stricter standards.

• International Variations

  • AQI systems vary globally. Examples include Canada's Air Quality Health Index (AQHI), China's Individual Air Quality Index (IAQI), and Europe's Common Air Quality Index (CAQI).

• Limitations of the AQI

  • Distance of Monitors: AQI readings are based on about 5,000 monitors across the U.S. These can be located miles away from an individual's home (e.g., 10+ miles), meaning they may not reflect the actual air quality at a specific residence.
  • Local Pollution Sources: The general AQI does not account for immediate, hyper-local pollution sources, such as a neighbor burning leaves or a truck idling nearby.

• Indoor Air Quality Myth

  • While Americans spend about 93% of their time indoors or in vehicles, they are not escaping outdoor pollution.
  • Outdoor air penetrates indoor environments. Because people spend so much time inside, the majority of their exposure to outdoor air pollution actually occurs indoors.

Tại Việt Nam, Tổ chức Y tế thế giới (WHO) coi ô nhiễm không khí là một trong những nguyên nhân gây ra gánh nặng bệnh tật và tử vong hàng đầu. Có khoảng 6/10 bệnh có tỷ lệ chết cao nhất tại Việt Nam là những bệnh liên quan đến không khí.

Tuy nhiên, việc sử dụng khẩu trang chỉ là một giải pháp tình thế. Theo TS Hoàng Dương Tùng, để hạn chế ô nhiễm bụi PM2.5 cần hướng tới giải quyết tận gốc. Nguyên nhân gây ra ô nhiễm bụi mịn PM2.5 được xác định từ các nguồn sản xuất, giao thông, xây dựng, sinh hoạt... Trong đó bốn ngành gồm sắt thép, nhiệt điện, xi măng, hóa chất đã gây ra 80% lượng ô nhiễm từ các nguồn ô nhiễm điểm.