Poor environment is connected with poor health. Now a new public-health     1     (tend)is becoming apparent: Making indoor air cleaner.

Let’s take schools for example. Across Denmark, France, and Sweden, researchers found that indoor-air quality in 66% of classrooms fell short     2     healthy standards. Outdoor-air pollution can get inside buildings — childhood     3     (expose)can affect their physical development and academic performance, and cause cancer.

The problem extends well beyond classrooms. Many people spend more than 90% of their time     4     (stay)indoors. Spaces in buildings with poor air may cause a range of diseases — headaches, shortness of breath, coughs and discomfort of eye, nose, throat and skin. Poor air     5     (blame)for decreased productivity in the past few years.

Covid-19 has brought a new urgency to the matter     6     (great). More investment would be well spent. Better indoor air improves academic development — math     7     reading scores go up. Meanwhile pupils are     8     (attentive)in class. Poor air indoors is the     9     (forget)part when people improved public health. Covid-19 should lead policymakers to focus on the problem,     10     is of great importance for people’s well-being.