Building ventilation is known to be effective for reducing the spread of airborne diseases such as tuberculosis, SARS, smallpox, chicken pox, and influenza in single indoor environments. Ventilation intervention decreases transmission probability by directing the flow of airborne infectious agents away from susceptible persons and/or by removing infectious agents from room air. Because it relies less on individual compliance, ventilation has an advantage over other non-pharmaceutical interventions (e.g., hand washing or mask use).
WHO: How Air Pollution Affects Your Health.
Past 24 Hours Pollutant Concentration Summary: http://www.aqhi.gov.hk/en/aqhi/past-24-hours-pollutant-concentration.html
Ambient (outdoor) air quality and health: http://www.who.int/mediacentre/factsheets/fs313/en/
Ventilation for Acceptable Indoor Air Quality: https://www.ashrae.org/File%20Library/docLib/Public/200418145036_347.pdf
Indoor air quality: https://en.m.wikipedia.org/wiki/Indoor_air_quality