“We are really safe to breathe indoor, because the building protects us from widely publicized effects of air pollution.” Well, this is not true, especially when you are working, living or studying in urban areas and even when you staying in suburb.
A report of indoor air pollution in London’s schools, published by UCL Institute for Environmental Design and Engineering, showed otherwise that “children living – or going to school – near busy roads were exposed to higher levels of vehicle pollution, and had a higher prevalence of childhood asthma and wheeze.” Additionally, We Design For (a leading IAQ consultancy in UK) had also found that “indoor air quality in buildings tested by the consultancy was worse than outdoor air quality.” Its director Pete Carvell added that “Conditions indoors are often worse. Urban dwellers need to be asking more questions about their indoor air quality. We need to be looking at what we can do to make indoor air quality better, just as we work to reduce outdoor air pollution.”
In these areas, a great deal of indoor air pollution is caused by outdoor pollution, like NO2 (outdoor sources accounted for 84%), traffic-related pollutants and small particles (exceeding PM guidance limits by up to 520%), which resulting to have higher risk of asthma attacks, asthmatic symptoms and other respiratory illness. Moreover, CO2, VOCs, microbes and allergens can be building up in the area and attaching to surfaces, without proper ventilation.
What steps can be taken?
1. Managing the source of pollutants.
a) Outdoor pollutants. Applying stricter policy to guide city planning and regulate the traffic properly, ensuring the city is green and clean. I believe most of the developed city had already put their hands on them and improving them day by day, but it requires a considerable period of time.
b) Indoor pollutants, like VOCs and allergens. These can be generated from materials in indoor area, like carpets, new furniture, paint and even toys in the room. Thus, we should choose carefully what we use for our homes and offices.
2. Application of suitable mechanical ventilation solutions.
Ventilation is very important to control the pollutants in the supplying fresh air, and also to remove indoor pollutants.
a) With the use of high efficiency filters, we can filtrate 95-99% of the PM10 and PM2.5, and also remove nitrogen dioxide, making sure the air is clean and safe to breathe.
b) When replacing the indoor stale air with the clean fresh air, the indoor pollutants will be removed gradually, ensuring that they are of low concentration, with little effect or no effect to the human body.
c) By mechanical ventilation, we can create a physical barrier by pressure difference – indoor slight positive pressure, so that the air will be exiting the area, thus to keep outdoor pollutants from entering.
Policies are not something that we can decide; therefore we should focus more on choosing greener materials and more importantly to get a suitable ventilation solution for your place!
https://www.cibsejournal.com/technical/learning-the-limits-how-outdoor-pollution-affects-indoor-air-quality-in-buildings/ 
