One way to put these estimates into perspective is to compare them to the effects of smoking.
The coefficients on smoking and number of cigarettes from the models for CO are shown in Table 3 (the estimated effects of smoking in models for other pollutants are very similar but are not shown).
In models that do not include maternal fixed effects, smoking is estimated to have extremely negative effects on infant health, consistent with much of the prior literature.
For example, being a smoker is estimated to reduce birth weight by 162 g in models that include monitor fixed effects, and each additional cigarette smoked reduces birth weight by 5 g, for a total reduction of approximately 212 g at the mean of 10 cigarettes per day.
However, as Almond et al. (2005) and Tominey (2007) point out, these estimates are likely to be contaminated by omitted
characteristics of the mother that are associated with her smoking behavior.